JP7622732B2 - Light emitting element - Google Patents

Description

The present disclosure relates to a light-emitting device, more specifically, a light-emitting device comprising a vertical cavity surface-emitting laser (VCSEL).

For example, in a light-emitting element consisting of a surface-emitting laser element disclosed in WO2018/083877A1, laser oscillation occurs by resonating laser light between two light reflecting layers (Distributed Bragg Reflector layer, DBR layer). In a surface-emitting laser element having a laminated structure in which an n-type compound semiconductor layer (first compound semiconductor layer), an active layer (light-emitting layer) consisting of a compound semiconductor, and a p-type compound semiconductor layer (second compound semiconductor layer) are laminated, a second electrode consisting of a transparent conductive material is formed on the p-type compound semiconductor layer, and a second light reflecting layer is formed on the second electrode. In addition, a first light reflecting layer and a first electrode are formed on the n-type compound semiconductor layer (on the exposed surface of the substrate when the n-type compound semiconductor layer is formed on a conductive substrate). In this specification, the concept of "upper" may refer to a direction away from the active layer based on the active layer, the concept of "lower" may refer to a direction approaching the active layer based on the active layer, and the concepts of "convex" and "concave" may refer to the active layer as a reference.

WO2018/083877A1

However, the transparent conductive material that constitutes the second electrode generally has a high electrical resistance. Therefore, when the area of the active layer (light-emitting layer) is increased, the area of the second electrode also inevitably becomes large, and it may become difficult for current to flow uniformly through the second electrode and further through the active layer.

Therefore, the object of the present disclosure is to provide a light-emitting element having a configuration and structure that enables current to flow uniformly through the active layer.

In order to achieve the above object, the light-emitting device of the present disclosure comprises:
a first compound semiconductor layer having a first surface and a second surface opposite to the first surface;
an active layer facing the second surface of the first compound semiconductor layer; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposite to the first surface;
A laminated structure in which
A first light reflecting layer formed on the first surface side of the first compound semiconductor layer;
a second light reflecting layer formed on the second surface side of the second compound semiconductor layer;
a first electrode electrically connected to the first compound semiconductor layer; and
a second electrode provided between the second compound semiconductor layer and the second light reflecting layer;
It is equipped with
The second electrode includes at least a nanocarbon material layer or a two-dimensional material layer.

FIG. 1 is a schematic partial end view of a light emitting element according to a first embodiment. FIG. 2 is a schematic partial end view of Modification 1 of the light emitting device of Example 1. FIG. FIG. 3 is a schematic partial end view of a modified example 2 of the light emitting device of the first embodiment. FIG. 4 is a schematic partial end view of a third modified example of the light emitting device of the first embodiment. FIG. 5 is a schematic partial end view of a fourth modified example of the light emitting device of the first embodiment. FIG. 6 is a schematic partial end view of a light emitting element according to a third embodiment. FIG. 7 is a schematic partial end view of the light emitting element of the fourth embodiment. FIG. 8 is a schematic partial end view of a first modified example of the light emitting device of the fourth embodiment. FIG. 9 is a schematic partial end view of the light emitting device of the fifth embodiment. FIG. 10 is a schematic partial end view of a light-emitting element array constituted by light-emitting elements according to the fifth embodiment. FIG. 11 is a diagram illustrating an arrangement of a first light reflecting layer and a first electrode in the light emitting element of Example 5. As shown in FIG. FIG. 12 is a diagram illustrating another example of the arrangement of the first light reflecting layer and the first electrode in the light emitting element of Example 5. In FIG. FIG. 13 is a schematic partial end view of the light emitting device of Example 6. As shown in FIG. FIG. 14 is a schematic partial end view of a light-emitting element array constituted by light-emitting elements according to the sixth embodiment. FIG. 15 is a schematic plan view showing the arrangement of the first and second portions of the base surface in a light-emitting element array constituted by the light-emitting elements of Example 6. FIG. FIG. 16 is a schematic plan view showing the arrangement of first light reflecting layers and first electrodes in a light emitting element array constituted by the light emitting elements of Example 6. As shown in FIG. FIG. 17 is a schematic plan view showing the arrangement of the first and second portions of the base surface in a light-emitting element array constituted by the light-emitting elements of Example 6. FIG. FIG. 18 is a schematic plan view showing the arrangement of the first light reflecting layer and the first electrode in a light emitting element array constituted by the light emitting elements of Example 6. As shown in FIG. FIG. 19 is a schematic partial end view of a light-emitting element array constituted by the light-emitting elements of the seventh embodiment. FIG. 20 is a schematic partial end view of a light-emitting element array constituted by a modified example of the light-emitting element of the seventh embodiment. FIG. 21 is a schematic plan view showing the arrangement of the first portion and the like in a light-emitting element array constituted by a modified example of the light-emitting element of the seventh embodiment. 22A and 22B are schematic plan views showing the arrangement of the first portion and the second portion of the base surface in the light-emitting element array of Example 8. FIG. FIG. 23 is a schematic partial cross-sectional view of a light-emitting element array constituted by a plurality of light-emitting elements of the tenth embodiment. FIG. 24 is a schematic partial cross-sectional view of the light-emitting device of Example 10. FIG. 25 is a schematic partial cross-sectional view of a light-emitting element array constituted by a plurality of light-emitting elements according to Modification 1 of the tenth embodiment. FIG. 26 is a schematic partial cross-sectional view of Modification 1 of the light-emitting device of Example 10. As shown in FIG. FIG. 27 is a schematic partial cross-sectional view of the light-emitting element array of the eleventh embodiment. FIG. 28 is a schematic partial cross-sectional view of the light-emitting device of Example 11. As shown in FIG. FIG. 29 is a schematic partial cross-sectional view of Modification 1 of the light-emitting device of Example 11. As shown in FIG. FIG. 30 is a schematic partial cross-sectional view of Modification 2 of the light-emitting device of Example 11. In FIG. FIG. 31 is a schematic partial cross-sectional view of Modification 3 of the light-emitting device of Example 11. In FIG. 32A and 32B are schematic partial end views of a laminated structure and the like for explaining a manufacturing method of the light emitting element of Example 1. FIG. 33 is a schematic partial end view of the laminated structure etc. for explaining the manufacturing method of the light emitting element of Example 1, following FIG. 32B. 34 is a schematic partial end view of the laminated structure etc. for explaining the manufacturing method of the light emitting element of Example 1, following FIG. 33. FIG. 35A, 35B, and 35C are schematic partial end views of the first compound semiconductor layer and the like for explaining the manufacturing method of the light-emitting element of Example 1, following FIG. 36A, 36B, and 36C are schematic partial end views of a laminated structure and the like for explaining a manufacturing method of the light-emitting element of Example 5. FIG. 37A, 37B, and 37C are schematic partial end views of a laminated structure and the like for explaining a manufacturing method of the light-emitting element of Example 5. FIG. 38A and 38B are schematic partial end views of the laminated structure and the like for explaining the manufacturing method of the light-emitting element of Example 5, following FIG. 36C. 39A and 39B are schematic partial end views of a first compound semiconductor layer and the like for illustrating a manufacturing method of the light emitting device of Example 6. FIG. 40A and 40B are schematic partial end views of a first compound semiconductor layer etc. for explaining the manufacturing method of the light-emitting element of Example 6, following FIG. 39B. 41A and 41B are schematic partial end views of a first compound semiconductor layer and the like for explaining the manufacturing method of the light-emitting element of Example 6, following FIG. 40B. 42A, 42B, and 42C are schematic partial end views of a laminated structure and the like for explaining a manufacturing method of the light-emitting element of Example 9. FIG. 43A and 43B are conceptual diagrams that typically show longitudinal modes present in a gain spectrum determined by an active layer. 44A, 44B, 44C, and 44D are schematic diagrams showing the fluctuation of the forbidden band due to the fluctuation of the Fermi level E _f in the band structure of graphene. FIG. 45 is a schematic partial cross-sectional view of the light-emitting device of Example 1, and a diagram in which two longitudinal modes, longitudinal mode A and longitudinal mode B, are superimposed.

Hereinafter, the present disclosure will be described based on examples with reference to the drawings, but the present disclosure is not limited to the examples, and various numerical values and materials in the examples are merely examples. The description will be made in the following order.
1. General Description of the Light-Emitting Element of the Present Disclosure 2. Example 1 (Light-Emitting Element of the Present Disclosure)
3. Example 2 (Modification of Example 1)
4. Example 3 (Modification of Examples 1 and 2)
5. Example 4 (another modification of Examples 1 and 2)
6. Example 5 (Modification of Examples 1 to 4)
7. Example 6 (Modification of Example 5)
8. Example 7 (Modification of Examples 5 to 6)
9. Example 8 (Modification of Example 5)
10. Example 9 (Modifications of Example 5, Example 4, and Example 5)
11. Example 10 (Modification of Examples 1 to 5)
12. Example 11 (Modification of Example 10)
13. Other

<General Description of Light-Emitting Element of the Present Disclosure>
In the light-emitting element of the present disclosure, the nanocarbon material layer can be made of at least one material selected from the group consisting of graphene, carbon nanotube, and fullerene. The two-dimensional material layer can be made of at least one material selected from the group consisting of silicene, germanene, stanene, plumbene, boron nitride (specifically, hexagonal boron nitride), and transition metal dichalcogenide-based materials, and further, in this case, when the transition metal dichalcogenide (TMDC)-based material is represented by MX ₂ , the transition metal "M" is one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Tc, and Re, and the chalcogen element "X" is one element selected from the group consisting of O, S, Se, and Te. Alternatively, CuS, which is a compound of Cu, a transition metal, and S, a chalcogen element, can be mentioned, as well as compounds of non-transition metals such as Ga, In, Ge, Sn, and _Pb , and chalcogen elements (e.g., GaS, GaSe, GaTe, _In2Se3 , InSnS2, _{SnSe2 ,} GeSe, _SnS2 , PbO), and black phosphorus can also be mentioned. Graphene refers to a sheet-like material of ^sp2- bonded carbon atoms with a thickness of one atom, and has a hexagonal lattice structure like a honeycomb made of carbon atoms and their bonds. Silicene is a graphene-like material in which the carbon atoms of graphene are replaced with silicon elements and crystallized in a honeycomb lattice, germanene is a graphene-like material in which the carbon atoms of graphene are replaced with germanium elements and crystallized in a honeycomb lattice, stanene is a graphene-like material in which the carbon atoms of graphene are replaced with tin elements and crystallized in a honeycomb lattice, and plumbene is a graphene-like material in which the carbon atoms of graphene are replaced with lead elements and crystallized in a honeycomb lattice, and these materials are also called post-graphene materials. The second electrode may have a laminated structure of at least a nanocarbon material layer and a two-dimensional material layer.

In the light-emitting device of the present disclosure including the above preferred embodiment, the second electrode can be in a form having a laminated structure of at least a first layer made of a transparent conductive material or a semiconductor material and a second layer made of a nanocarbon material layer or a two-dimensional material layer. In this case, the first layer can be in contact with the second compound semiconductor layer. Furthermore, the second layer can be not formed in the center of the second electrode, thereby suppressing the emission of high-order mode light emitted from the active layer. The diameter of the region where the second layer is not formed is R _CL . The second electrode can also be in a form having a laminated structure of, for example, a first layer made of a transparent conductive material or a semiconductor material, a second layer made of a nanocarbon material layer or a two-dimensional material layer, and a third layer made of a transparent conductive material or a semiconductor material. Hereinafter, the nanocarbon material layer and the two-dimensional material layer may be collectively referred to as "nanocarbon material layer, etc.".

In the embodiment in which the second layer is not formed in the center of the second electrode, it is preferable that the second layer is disposed at a position that does not satisfy the following formula (A). This allows the second layer (nanocarbon material layer, etc.) to function as a light absorbing material layer and absorb the high-order mode light emitted from the active layer, thereby ensuring transverse mode control of the light emitted from the active layer.

When the length L _OR of the resonator formed by the first light reflecting layer and the second light reflecting layer is several times or more longer than the wavelength of the light emitted from the light emitting element, the nano carbon material layer or the like absorbs the light emitted from the light emitting element, resulting in multiple types of longitudinal mode light that can be emitted from the light emitting element (see the conceptual diagram in Figure 43B), which may make it difficult to accurately control the oscillation wavelength of the light emitted from the light emitting element.

Therefore, in the light-emitting device of the present disclosure including the preferred embodiments described above, when the distance in the thickness direction of the laminate structure from the center of the active layer in the thickness direction to the center of the nanocarbon material layer or the two-dimensional material layer in the thickness direction is L ₂ , the oscillation wavelength is λ ₀ , and the equivalent refractive index of the portion located from the center of the active layer in the thickness direction to the center of the nanocarbon material layer or the two-dimensional material layer in the thickness direction is n _eq ,
0.9×{(m+1)λ ₀ )/(4・n _eq )}≦L ₂ ≦1.1×{(m+1)λ ₀ )/(4・n _eq )} (A)
Here, m is an arbitrary integer of 0 or 2 or more including 1. By adopting such a configuration, it becomes possible to position the nanocarbon material layer constituting the second electrode at the minimum amplitude part of the light intensity distribution, so that the nanocarbon material layer constituting the second electrode is less likely to absorb the light generated in the active layer, and the light in the longitudinal mode that can be emitted from the light emitting element becomes one type (see the conceptual diagram of FIG. 43A ). It becomes possible to accurately control the oscillation wavelength of the light in the longitudinal mode emitted from the light emitting element, so that the light emitting efficiency of the light emitting element can be improved, and the oscillation wavelength of the light emitted from the light emitting element becomes single, making it possible to accurately control the emission wavelength. Here, the equivalent refractive index n _eq is, when the thickness of each of the layers made of various materials constituting the part located from the center of the active layer in the thickness direction to the center of the nanocarbon material layer in the thickness direction is t _i and the refractive index of each of the layers is n _i ,
n _eq =Σ(t _i ×n _i )/Σ(t _i )
where i=1, 2, 3, ..., I, "I" is the total number of layers made of various materials constituting the portion located from the center of the active layer in the thickness direction to the center of the nanocarbon material layer in the thickness direction, and "Σ" means taking the sum from i=1 to i=I. The equivalent refractive index n _eq may be calculated based on the known refractive index and thickness obtained by observation of each constituent material by observing the constituent materials through electron microscope observation of the cross section of the light emitting element. Note that the nanocarbon material layer, etc. preferably has a narrower band gap than the compound semiconductor constituting the laminated structure, and thus the nanocarbon material layer, etc. also functions as a light absorbing material layer.

Furthermore, in the light-emitting element of the present disclosure, including the preferred forms described above, the thickness of the nanocarbon material layer or two-dimensional material layer constituting the second electrode is preferably, but not limited to, greater than 0 nm and less than 5 nm.

Furthermore, in the light-emitting device according to the present disclosure including the preferred embodiment described above, at least a part of the second compound semiconductor layer in the thickness direction is composed of a current injection region and a current non-injection region surrounding the current injection region,
The diameter R _CC of the current injection region on the second surface of the second compound semiconductor layer is not limited, but may be 1×10 ⁻⁶ m to 1×10 ⁻² m, preferably 2×10 ⁻⁶ m to 1×10 ⁻³ m. The current confinement region is defined by the current injection region. When the planar shape of the current injection region is not circular, the diameter of a circle that is assumed to be equal to the area of the current injection region is taken as the diameter R _CC of the current injection region. The relationship between the diameter R _CL and the diameter R _CC is as follows:
0.05R _CC <R _CL <0.95R _CC
Examples include:

Alternatively, in the light-emitting device according to the present disclosure including the preferred embodiments described above,
the second compound semiconductor layer is partitioned into a first region and a second region surrounding the first region;
a second electrode is provided on the first region of the second compound semiconductor layer;
The second region of the second compound semiconductor layer may be configured to face the second electrode via an insulating layer.

Furthermore, in the light-emitting element of the present disclosure including the preferred forms and configurations described above, the second electrode may have a plurality of grooves extending in one direction (for example, a first direction) in order to control the polarization state of light emitted from the light-emitting element. Specifically, the plurality of grooves extending in the first direction are parallel to a virtual plane (XY plane described later) perpendicular to the thickness direction of the second electrode, and when the groove formation pitch P ₀ is significantly smaller than the wavelength λ ₀ of the incident light, the light vibrating in a plane parallel to the extension direction (first direction) of the grooves is selectively reflected and absorbed in the grooves. Here, the distance between the line portions of the grooves (the distance of the space portion along the second direction) is defined as the groove formation pitch P _0. Then, the light (electromagnetic wave) that reaches the grooves contains a vertically polarized component and a horizontally polarized component, but the electromagnetic wave that passes through the grooves becomes linearly polarized light in which the vertically polarized component is dominant. Here, when considering the visible light wavelength band, if the pitch P ₀ of the grooves is significantly smaller than the effective wavelength λ _eff of the light (electromagnetic wave) incident on the grooves, the polarized component biased to the plane parallel to the first direction is reflected or absorbed on the surface of the grooves. On the other hand, when light having a polarized component biased to the plane parallel to the second direction is incident on the grooves, the electric field (light) propagated on the surface of the grooves transmits (emits) with the same wavelength and polarization direction as the incident wavelength from the back surface of the grooves. Here, when the average refractive index determined based on the material present in the space portion is n _ave , the effective wavelength λ _eff is expressed as (λ ₀ /n _ave ). The average refractive index n _ave is the value obtained by adding the product of the refractive index and volume of the material present in the space portion and dividing it by the volume of the space portion. When the value of the wavelength λ ₀ is constant, the smaller the value of n _ave , the larger the value of the effective wavelength λ _eff , and therefore the value of the formation pitch P ₀ can be increased. Moreover, the larger the value of n _ave , the lower the transmittance in the grooves and the lower the extinction ratio.

Furthermore, in the light-emitting device of the present disclosure including the preferred forms and configurations described above, the first light reflecting layer may have a convex shape facing away from the active layer, and the second light reflecting layer may have a flat shape. In this case, the radius of curvature _R1 of the portion of the first light reflecting layer having a convex shape may be, but is not limited to, 1×10 ⁻⁵ m to 1×10 ⁻² m, preferably 3×10 ⁻⁵ m to 1×10 ⁻³ m. In either case, however, the value of _R1 is greater than the value of the cavity length L _OR .

Here, when the second surface of the first compound semiconductor layer is used as a reference, a first portion of the base surface (described later) on which the first light reflecting layer is formed has an upwardly convex shape. The portion of the base surface that is outside the first portion is called the second portion, and when the second surface of the first compound semiconductor layer is used as a reference, the second portion is either flat or concave toward the second surface. The second portion of the base surface is sometimes called the peripheral region. An extension of the first light reflecting layer may be formed on the second portion of the base surface, or the first light reflecting layer may not be formed on the second portion.

When the second portion of the base surface is concave toward the second surface of the first compound semiconductor layer as described above, the radius of curvature _R2 of the central portion of the second portion of the base surface is desirably 1× ^10-6 m or more, preferably 3× ^10-6 m or more, and more preferably 5× ^10-6 m or more, and when the second portion of the base surface is annular, the radius of curvature _R2 ' of the apex of the annular convex shape of the second portion is desirably 1× ^10-6 m or more, preferably 3× ^10-6 m or more, and more preferably 5× ^10-6 m or more.

When a light-emitting element array is constructed from a plurality of juxtaposed light-emitting elements, the center of the first portion of the base surface can be configured to be located on the vertex (intersection) of a square lattice, and in this case, the center of the second portion of the base surface can be configured to be located on the vertex (intersection) of the square lattice. Alternatively, the center of the first portion of the base surface can be configured to be located on the vertex (intersection) of an equilateral triangular lattice, and in this case, the center of the second portion of the base surface can be configured to be located on the vertex (intersection) of the equilateral triangular lattice.

The figure drawn by the first or second part of the base surface when the first or second part of the base surface is cut in a virtual plane (XZ plane described later) including the stacking direction of the laminated structure can be a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve. The figure may not be a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve in the strict sense. In other words, the figure may be a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve, even if it is approximately a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve. Some of these curves may be replaced with line segments. The figure drawn by the base surface can be obtained by measuring the shape of the base surface with a measuring instrument and analyzing the obtained data based on the least squares method.

A bump may be provided on the portion of the second compound semiconductor layer facing the second portion of the base surface. Alternatively, a bump may be provided on the portion of the second compound semiconductor layer facing the center of the first portion of the base surface. Examples of the bump include a gold (Au) bump, a solder bump, and an indium (In) bump, and the bump may be provided by a known method. Specifically, the bump is provided on a second pad electrode (described later) provided on the second electrode, or on an extension of the second pad electrode.

Furthermore, in the light-emitting device of the present disclosure including the preferred embodiments and configurations described above, the cavity length L _OR can be, but is not limited to, 1×10 ⁻⁶ m to 5×10 ⁻⁴ m.

In the light-emitting device of the present disclosure including the preferred embodiments and configurations described above (hereinafter referred to as the "light-emitting device of the present disclosure, etc."), the laminated structure may be made of at least one material selected from the group consisting of GaN-based compound semiconductors, InP-based compound semiconductors, and GaAs-based compound semiconductors.
(a) a configuration made of a GaN-based compound semiconductor; (b) a configuration made of an InP-based compound semiconductor; (c) a configuration made of a GaAs-based compound semiconductor; (d) a configuration made of a GaN-based compound semiconductor and an InP-based compound semiconductor; (e) a configuration made of a GaN-based compound semiconductor and a GaAs-based compound semiconductor; (f) a configuration made of an InP-based compound semiconductor and a GaAs-based compound semiconductor; and (g) a configuration made of a GaN-based compound semiconductor, an InP-based compound semiconductor, and a GaAs-based compound semiconductor.

In the light-emitting element etc. of the present disclosure, the thermal conductivity value of the laminated structure can be configured to be higher than the thermal conductivity value of the first light reflecting layer. The thermal conductivity value of the dielectric material constituting the first light reflecting layer is generally about 10 watts/(m·K) or less. On the other hand, the thermal conductivity value of the GaN-based compound semiconductor constituting the laminated structure is about 50 watts/(m·K) to about 100 watts/(m·K).

In the light-emitting element etc. disclosed herein, when various compound semiconductor layers (including compound semiconductor substrates) are present between the active layer and the first light reflecting layer, it is preferable that the materials constituting these various compound semiconductor layers (including compound semiconductor substrates) have no refractive index modulation of 10% or more (no refractive index difference of 10% or more based on the average refractive index of the laminated structure), thereby making it possible to suppress the occurrence of disturbances in the optical field within the resonator.

The light-emitting element of the present disclosure can be used to form a surface-emitting laser element (vertical cavity laser, VCSEL) that emits laser light through a first light-reflecting layer, or a surface-emitting laser element that emits laser light through a second light-reflecting layer. In some cases, the substrate for manufacturing the light-emitting element (described later) may be removed.

In the light-emitting element and the like of the present disclosure, the stacked structure can be specifically, as described above, composed of, for example, an AlInGaN-based compound semiconductor. More specifically, the AlInGaN-based compound semiconductor can be GaN, AlGaN, InGaN, and AlInGaN. Furthermore, these compound semiconductors may contain boron (B) atoms, thallium (Tl) atoms, arsenic (As) atoms, phosphorus (P) atoms, and antimony (Sb) atoms as desired. The active layer desirably has a quantum well structure. Specifically, it may have a single quantum well structure (SQW structure) or a multiple quantum well structure (MQW structure). The active layer having a quantum well structure has a structure in which at least one well layer and one barrier layer are laminated, and examples of the combination of (compound semiconductor constituting the well layer, compound semiconductor constituting the barrier layer) include ( _{InyGa (1-y)} N, GaN), ( _InyGa ( _1-y) N, _{InzGa (1-z)} N) [where y>z], and ( _{InyGa (1-y)} N, AlGaN). The first compound semiconductor layer can be composed of a compound semiconductor of a first conductivity type (e.g., n-type), and the second compound semiconductor layer can be composed of a compound semiconductor of a second conductivity type (e.g., p-type) different from the first conductivity type. The first compound semiconductor layer and the second compound semiconductor layer are also called a first cladding layer and a second cladding layer. The first compound semiconductor layer and the second compound semiconductor layer may be a layer of a single structure, a layer of a multilayer structure, or a layer of a superlattice structure. Furthermore, it may be a layer having a composition gradient layer or a concentration gradient layer.

Alternatively, examples of group III atoms constituting the laminated structure include gallium (Ga), indium (In), and aluminum (Al), and examples of group V atoms constituting the laminated structure include arsenic (As), phosphorus (P), antimony (Sb), and nitrogen (N). Specific examples of the semiconductors that constitute the active layer include AlAs, GaAs, AlGaAs, AlP, GaP, GaInP, AlInP, AlGaInP, AlAsP, GaAsP, AlGaAsP, AlInAsP, GaInAsP, AlInAs, GaInAs, AlGaInAs, AlAsSb, GaAsSb, AlGaAsSb, AlN, GaN, InN, AlGaN, GaNAs, and GaInNAsSb.

Examples of the quantum well structure include a two-dimensional quantum well structure, a one-dimensional quantum well structure (quantum wire), and a zero-dimensional quantum well structure (quantum dot). Examples of materials constituting quantum wells include Si; Se; chalcopyrite compounds such as CIGS (CuInGaSe), CIS (CuInSe ₂ ), CuInS ₂ , CuAlS ₂ , CuAlSe ₂ , CuGaS 2 , CuGaSe ₂ , AgAlS _{2 , AgAlSe 2 ,} AgInS ₂ , and AgInSe ₂ ; perovskite materials; III-V compounds such as GaAs, GaP, InP, AlGaAs, InGaP, AlGaInP, _InGaAsP , GaN, InAs, InGaAs, GaInNAs, GaSb, and GaAsSb; CdSe, CdSeS, CdS, CdTe, In ₂ Se ₃ , and In ₂ S _{3 .} , _Bi2Se3 , _Bi2S3 , ZnSe, ZnTe, _ZnS , HgTe _, HgS, PbSe, PbS, _TiO2, etc., but are not limited to these.

The laminated structure is formed on the second surface of the substrate for manufacturing the light-emitting element, or on the second surface of the compound semiconductor substrate. The second surface of the substrate for manufacturing the light-emitting element or the compound semiconductor substrate faces the first surface of the first compound semiconductor layer, and the first surface of the substrate for manufacturing the light-emitting element or the compound semiconductor substrate faces the second surface of the substrate for manufacturing the light-emitting element or the compound semiconductor substrate. Examples of the substrate for manufacturing the light-emitting element include a GaN substrate, a sapphire substrate, a GaAs substrate, a SiC substrate, an alumina substrate, a ZnS substrate, a ZnO substrate, an AlN substrate, a LiMgO substrate, a _LiGaO2 substrate, _{a MgAl2O4} substrate, an InP substrate, and a Si substrate, and substrates having a base layer or a buffer layer formed on the surface (main surface) of these substrates, but the use of a GaN substrate is preferred because of its low defect density. Examples of the compound semiconductor substrate include a GaN substrate, an InP substrate, and a GaAs substrate. It is known that the characteristics of a GaN substrate vary from polar to non-polar to semi-polar depending on the growth surface, but any of the main surfaces (second surfaces) of the GaN substrate can be used to form a compound semiconductor layer. In addition, with regard to the main surface of the GaN substrate, depending on the crystal structure (e.g., cubic crystal type, hexagonal crystal type, etc.), crystal plane orientations called so-called A-plane, B-plane, C-plane, R-plane, M-plane, N-plane, S-plane, etc., or planes off these in a specific direction, etc. can be used. Examples of methods for forming various compound semiconductor layers constituting the light-emitting element include, but are not limited to, metal organic chemical vapor deposition (MOCVD, Metal Organic-Chemical Vapor Deposition, MOVPE, Metal Organic-Vapor Phase Epitaxy), molecular beam epitaxy (MBE), hydride vapor phase epitaxy (HVPE) in which halogen contributes to transport or reaction, atomic layer deposition (ALD, Atomic Layer Deposition), migration-enhanced epitaxy (MEE, Migration Enhanced Epitaxy), and plasma-assisted physical vapor deposition (PPD).

GaAs and InP materials also have a zinc blende structure. The main surfaces of compound semiconductor substrates made of these materials can include (100), (111)AB, (211)AB, (311)AB, and other surfaces, as well as surfaces off-axis in a specific direction. Note that "AB" means that the off-axis direction is different by 90 degrees, and the off-axis direction determines whether the main material of the surface is group III or group V. By controlling these crystal plane orientations and deposition conditions, it is possible to control the composition unevenness and dot shape. As with GaN, deposition methods such as MBE, MOCVD, MEE, and ALD are commonly used, but are not limited to these methods.

Here, in the formation of the GaN-based compound semiconductor layer, trimethylgallium (TMG) gas or triethylgallium (TEG) gas can be used as the organic gallium source gas in the MOCVD method, and ammonia gas or hydrazine gas can be used as the nitrogen source gas. In the formation of the GaN-based compound semiconductor layer having n-type conductivity, for example, silicon (Si) can be added as an n-type impurity (n-type dopant), and in the formation of the GaN-based compound semiconductor layer having p-type conductivity, for example, magnesium (Mg) can be added as a p-type impurity (p-type dopant). When aluminum (Al) or indium (In) is included as the constituent atoms of the GaN-based compound semiconductor layer, trimethylaluminum (TMA) gas can be used as the Al source, and trimethylindium (TMI) gas can be used as the In source. Furthermore, monosilane gas ( _SiH4 gas) may be used as the Si source, and biscyclopentadienyl magnesium gas, methylcyclopentadienyl magnesium, or biscyclopentadienyl magnesium ( _Cp2Mg ) may be used as the Mg source. Note that examples of n-type impurities (n-type dopants) include Ge, Se, Sn, C, Te, S, O, Pd, and Po, in addition to Si, and examples of p-type impurities (p-type dopants) include Zn, Cd, Be, Ca, Ba, C, Hg, and Sr, in addition to Mg.

When the laminated structure is made of an InP-based compound semiconductor or a GaAs-based compound semiconductor, metalorganic raw materials such as TMGa, TEGa, TMIn, and TMAl are generally used as group III raw materials. In addition, metalorganic raw materials such as arsine gas (AsH ₃ gas), phosphine gas (PH ₃ gas), and ammonia (NH ₃ ) are used as group V raw materials. In addition, metalorganic raw materials may be used as group V raw materials, such as tertiary butyl arsine (TBAs), tertiary butyl phosphine (TBP), dimethyl hydrazine (DMHy), and trimethyl antimony (TMSb). These materials decompose at low temperatures, and are therefore effective in low-temperature growth. As n-type dopants, monosilane (SiH ₄ ) is used as a Si source, and hydrogen selenide (H ₂ Se) is used as a Se source. As the p-type dopant, dimethyl zinc (DMZn), biscyclopentadienyl magnesium (Cp ₂ Mg), etc. As the dopant material, the same materials as those of the GaN system are candidates.

The first surface of the first compound semiconductor layer may constitute the base surface. Alternatively, a compound semiconductor substrate (or a substrate for manufacturing a light-emitting device) may be disposed between the first surface of the first compound semiconductor layer and the first light reflecting layer, and the base surface may be constituted by the surface of the compound semiconductor substrate (or a substrate for manufacturing a light-emitting device). In this case, for example, the compound semiconductor substrate may be constituted by a GaN substrate. As the GaN substrate, any of a polar substrate, a semi-polar substrate, and a non-polar substrate may be used. The thickness of the compound semiconductor substrate may be, for example, 5×10 ⁻⁵ m to 1×10 ⁻⁴ m, but is not limited to such values. Alternatively, a substrate may be disposed between the first surface of the first compound semiconductor layer and the first light reflecting layer, or a compound semiconductor substrate and a substrate may be disposed between the first surface of the first compound semiconductor layer and the first light reflecting layer, and the base surface may be constituted by the surface of the substrate. Examples of materials constituting the substrate include transparent dielectric materials such as TiO ₂ , Ta ₂ O ₅ , and SiO ₂ , silicone-based resins, and epoxy-based resins.

In the manufacture of the light-emitting element and the like of the present disclosure, the substrate for manufacturing the light-emitting element may be left as it is, or the active layer, the second compound semiconductor layer, the second electrode, and the second light reflecting layer may be formed in sequence on the first compound semiconductor layer, and then the substrate for manufacturing the light-emitting element may be removed. Specifically, the active layer, the second compound semiconductor layer, the second electrode, and the second light reflecting layer may be formed in sequence on the first compound semiconductor layer formed on the substrate for manufacturing the light-emitting element, and then the second light reflecting layer may be fixed to a support substrate, and then the substrate for manufacturing the light-emitting element may be removed to expose the first compound semiconductor layer (the first surface of the first compound semiconductor layer). The substrate for manufacturing a light-emitting element can be removed by a wet etching method using an alkaline aqueous solution such as a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, an ammonia solution + hydrogen peroxide solution, a sulfuric acid solution + hydrogen peroxide solution, a hydrochloric acid solution + hydrogen peroxide solution, a phosphoric acid solution + hydrogen peroxide solution, or the like; a dry etching method such as a chemical mechanical polishing method (CMP method), a mechanical polishing method, or a reactive ion etching (RIE) method; a lift-off method using a laser, or a combination of these.

The support substrate for fixing the second light reflecting layer may be composed of, for example, various substrates exemplified as substrates for manufacturing light emitting elements, or may be composed of an insulating substrate made of AlN or the like, a semiconductor substrate made of Si, SiC, Ge or the like, a metal substrate or an alloy substrate, but it is preferable to use a substrate having electrical conductivity, or it is preferable to use a metal substrate or an alloy substrate from the viewpoints of mechanical properties, elastic deformation, plastic deformation, heat dissipation, etc. Examples of the thickness of the support substrate include 0.05 mm to 1 mm. As a method for fixing the second light reflecting layer to the support substrate, known methods such as solder bonding, room temperature bonding, bonding using adhesive tape, bonding using wax bonding, and bonding using adhesives can be used, but from the viewpoint of ensuring electrical conductivity, it is preferable to adopt the solder bonding method or the room temperature bonding method. For example, when a silicon semiconductor substrate, which is a conductive substrate, is used as the support substrate, it is preferable to adopt a method that allows bonding at a low temperature of 400 ° C or less in order to suppress warping due to differences in thermal expansion coefficients. When a GaN substrate is used as the support substrate, the bonding temperature may be 400 ° C or more.

When a light-emitting element array is constructed from a plurality of light-emitting elements arranged side by side, the first electrode electrically connected to the first compound semiconductor layer is common to the plurality of light-emitting elements, and the second electrode electrically connected to the second compound semiconductor layer is common to the plurality of light-emitting elements, or may be provided individually for the plurality of light-emitting elements.

If the substrate for manufacturing the light-emitting element remains, the first electrode may be formed on the first surface opposite the second surface of the substrate for manufacturing the light-emitting element, or may be formed on the first surface opposite the second surface of the compound semiconductor substrate. If the substrate for manufacturing the light-emitting element does not remain, the first electrode may be formed on the first surface of the first compound semiconductor layer constituting the laminated structure. In this case, since the first light reflecting layer is formed on the first surface of the first compound semiconductor layer, the first electrode may be formed, for example, to surround the first light reflecting layer. The first electrode preferably has a single-layer structure or a multi-layer structure containing at least one metal (including alloy) selected from the group consisting of gold (Au), silver (Ag), palladium (Pd), platinum (Pt), nickel (Ni), Ti (titanium), vanadium (V), tungsten (W), chromium (Cr), Al (aluminum), Cu (copper), Zn (zinc), tin (Sn) and indium (In). Specifically, for example, Ti/Au, Ti/Al, Ti/Al/Au, Ti/Pt/Au, Ni/Au, Ni/Au/Pt, Ni/Pt, Pd/Pt, Ag/Pd can be exemplified. Note that the layer before the "/" in the multi-layer structure is located closer to the active layer side. The same applies to the following explanation. The first electrode can be formed by a PVD method such as a vacuum deposition method or a sputtering method.

When the first electrode is formed to surround the first light reflecting layer, the first light reflecting layer and the first electrode may be in contact with each other. Alternatively, the first light reflecting layer and the first electrode may be spaced apart. In some cases, the first electrode may be formed up to the edge of the first light reflecting layer, or the first light reflecting layer may be formed up to the edge of the first electrode.

As described above, the first layer constituting the second electrode can be made of a transparent conductive material. Examples of the transparent conductive material include indium-based transparent conductive materials [specifically, for example, indium-tin oxide (ITO, indium tin oxide, Sn-doped In ₂ O ₃ , including crystalline ITO and amorphous ITO), indium-zinc oxide (IZO), indium-gallium oxide (IGO), indium-doped gallium-zinc oxide (IGZO, In-GaZnO ₄ ), IFO (F-doped In ₂ O ₃ ), ITiO (Ti-doped In ₂ O ₃ ), InSn, and InSnZnO], and tin-based transparent conductive materials [specifically, for example, tin oxide (SnO _x ), ATO (Sb-doped SnO ₂ ), and FTO (F-doped SnO _{2 )} ]. )], zinc-based transparent conductive material [specifically, for example, zinc oxide (including ZnO, Al-doped ZnO (AZO) and B-doped ZnO), gallium-doped zinc oxide (GZO), AlMgZnO (aluminum oxide and magnesium oxide-doped zinc oxide)], NiO, TiO _x can be exemplified. Alternatively, as a material constituting the first layer, a transparent conductive film having a base layer of gallium oxide, titanium oxide, niobium oxide, antimony oxide, nickel oxide, etc. can be exemplified, and a transparent conductive material such as a spinel type oxide or an oxide having a YbFe ₂ O ₄ structure can also be exemplified. The first layer can be formed by a PVD method such as a vacuum deposition method or a sputtering method. Alternatively, a low-resistance semiconductor layer can be used as the first layer, and in this case, specifically, an n-type GaN-based compound semiconductor layer can be used. Furthermore, when an n-type GaN-based compound semiconductor layer and an adjacent layer are p-type, the electrical resistance at the interface can be reduced by joining the two via a tunnel junction.

A first pad electrode and a second pad electrode may be provided on the first electrode and the second electrode to electrically connect with an external electrode or circuit (hereinafter, sometimes referred to as "external circuit, etc."). The pad electrode preferably has a single-layer structure or a multi-layer structure containing at least one metal selected from the group consisting of Ti (titanium), aluminum (Al), Pt (platinum), Au (gold), Ni (nickel), and Pd (palladium). Alternatively, the pad electrode may have a multi-layer structure such as a Ti/Pt/Au multi-layer structure, a Ti/Au multi-layer structure, a Ti/Pd/Au multi-layer structure, a Ti/Pd/Au multi-layer structure, a Ti/Ni/Au multi-layer structure, or a Ti/Ni/Au/Cr/Au multi-layer structure. When the first electrode is composed of an Ag layer or an Ag/Pd layer, it is preferable to form a cover metal layer, for example, of Ni/TiW/Pd/TiW/Ni, on the surface of the first electrode, and to form a pad electrode, for example, of a multilayer structure of Ti/Ni/Au or a multilayer structure of Ti/Ni/Au/Cr/Au, on the cover metal layer.

The light reflecting layer (distributed Bragg reflector layer, DBR layer) constituting the first light reflecting layer and the second light reflecting layer is composed of, for example, a semiconductor multilayer film or a dielectric multilayer film. Examples of the dielectric material include oxides, nitrides (e.g., _SiNx , _AlNx , _AlGaNx , _GaNx , _BNx , etc.) or fluorides of Si, Mg, Al, Hf, Nb, Zr, Sc, Ta, Ga, Zn, Y, B, Ti, etc. Specific examples include _SiOx , _TiOx , _NbOx , _ZrOx , _TaOx , _ZnOx , _AlOx , _HfOx , _SiNx , AlNx _, etc. Among these dielectric materials, two or more types of dielectric films made of dielectric materials with different refractive indices are alternately stacked to obtain a light reflecting layer. For example, multilayer films such as _SiOx / _SiNy , _SiOx / _TaOx , _SiOx / _NbOy , _SiOx / _ZrOy , and _SiOx / _AlNy are preferred. In order to obtain a desired light reflectance, the material, film thickness, number of layers, and the like constituting each dielectric film may be appropriately selected. The thickness of each dielectric film can be appropriately adjusted depending on the material used, and is determined by the oscillation wavelength (light emission wavelength) _λ0 and the refractive index n at the oscillation wavelength _λ0 of the material used. Specifically, it is preferable to set the thickness to an odd multiple of _λ0 /(4n). For example, in a light emitting device with an oscillation wavelength _λ0 of 410 nm, when the light reflecting layer is composed of _SiOx / _NbOy , the thickness can be exemplified as about 40 nm to 70 nm. The number of layers can be exemplified as 2 or more, preferably 5 to 20. The thickness of the entire light reflecting layer can be exemplified as about 0.6 μm to 1.7 μm. In addition, it is desirable that the light reflecting layer has a light reflectance of 95% or more. The size and shape of the light reflecting layer are not particularly limited as long as it covers the current injection region or the element region (which will be described later).

The light-reflecting layer can be formed based on well-known methods, such as PVD methods such as vacuum deposition, sputtering, reactive sputtering, ECR plasma sputtering, magnetron sputtering, ion beam assisted deposition, ion plating, and laser ablation; various CVD methods; coating methods such as spraying, spin coating, and dipping; a method combining two or more of these methods; and a method combining these methods with one or more of the following: full or partial pretreatment, irradiation with an inert gas (Ar, He, Xe, etc.) or plasma, irradiation with oxygen gas, ozone gas, or plasma, oxidation treatment (heat treatment), and exposure treatment.

As described above, a current injection region is provided to regulate the current injection into the active layer. The shape of the boundary between the current injection region and the non-current injection region, and the planar shape of the opening provided in the element region and the current confinement region can be, specifically, a circle, an ellipse, an oval, a rectangle, or a regular polygon (equilateral triangle, square, regular hexagon, etc.). Here, the "element region" refers to the region where the confined current is injected, or the region where light is confined due to a refractive index difference, or the region where laser oscillation occurs within the region sandwiched between the first light reflection layer and the second light reflection layer, or the region that actually contributes to laser oscillation within the region sandwiched between the first light reflection layer and the second light reflection layer.

The nanocarbon material layer constituting the second electrode can be obtained, for example, by forming a film of these material layers on a support member, then fixing (transferring) these material layers to the second compound semiconductor layer or the first layer, and then removing the support member, or by various CVD methods, various PVD methods, liquid phase growth methods, etc., but is not limited to these methods.

Alternatively, graphene can be formed, for example, by the manufacturing method described below. That is, a film containing a graphene catalyst is formed on a support member. Then, a gas-phase carbon source is supplied to the film containing the graphene catalyst, and the gas-phase carbon source is heat-treated to generate graphene. Then, the graphene is cooled at a predetermined cooling rate, so that a film-like graphene can be formed on the film containing the graphene catalyst. Examples of the graphene catalyst include carbon compounds such as SiC, as well as at least one metal selected from Ni, Co, Fe, Pt, Au, Al, Cr, Cu, Mg, Mn, Mo, Rh, Si, Ta, Ti, W, U, V, and Zr. Examples of the gas-phase carbon source include at least one carbon source selected from carbon monoxide, methane, ethane, ethylene, ethanol, acetylene, propane, butane, butadiene, pentane, pentene, cyclopentadiene, hexane, cyclohexane, benzene, and toluene. The film-like graphene thus formed can be finally separated from the membrane containing the graphene catalyst to obtain graphene. However, the method for producing graphene is not limited thereto.

As shown in FIG. 44A, unlike ordinary semiconductors, graphene is a zero-gap semiconductor in which the valence band and the conduction band have a linear dispersion relationship with the Dirac point Dp as a symmetric point. Usually, the Fermi level E _f exists at the Dirac point Dp, but it can be shifted by applying a voltage or by a doping process. For example, as shown in FIG. 44B, when the Fermi level E _f is moved by applying a voltage or by a doping process, an optical transition of an energy larger than 2|ΔE _f | is possible, for example, as shown by the arrow E _a . On the other hand, as shown by the arrow E _b , an optical transition of an energy of 2|ΔE _f | or less can be prohibited. That is, graphene is transparent to light having an energy of 2|ΔE _f | or less. In this way, in graphene, the light transmittance for light of a desired wavelength (frequency) can be changed (controlled) by shifting the Fermi level E _f . As shown in FIG. 44C, when graphene is doped with an n-type impurity, the Fermi level E _f can be shifted from the Dirac point Dp to the conduction band side. On the other hand, as shown in FIG. 44D, when graphene is doped with a p-type impurity, the Fermi level E _f can be shifted from the Dirac point D p toward the valence band side.

In order to dope the graphene layer with n-type or p-type impurities, for example, chemical doping may be performed. To perform chemical doping, specifically, a dopant layer may be formed on the graphene layer. The dopant layer may be an electron-accepting (p-type) dopant layer, or an electron-donating (n-type) dopant layer. Materials constituting the electron-accepting (p-type) dopant layer include chlorides such as AuCl ₃ , HAuCl ₄ , and PtCl ₄ ; acids such as HNO ₃ , H ₂ SO ₄ , HCl, and nitromethane; Group III elements such as boron and aluminum; and electron-withdrawing molecules such as oxygen. Materials constituting the electron-donating (n-type) dopant layer include Group V elements such as nitrogen and phosphorus, as well as electron-donating molecules such as pyridine-based compounds, nitrides, alkali metals, and aromatic compounds having alkyl groups.

The side surface or exposed surface of the laminated structure may be covered with a coating layer (insulating film). The coating layer (insulating film) may be formed based on a known method. The refractive index of the material constituting the coating layer (insulating film) is preferably smaller than the refractive index of the material constituting the laminated structure. Examples of materials constituting the coating layer (insulating film) include _SiO2- containing _SiOx- based materials, _SiNx- based materials, _{SiOyNz -} based materials, _TaOx , _ZrOx , _AlNx , _AlOx , and _GaOx , or organic materials such as polyimide resins. Examples of methods for forming the coating layer (insulating film) include PVD methods such as vacuum deposition and sputtering, or CVD methods, and the coating layer (insulating film) may also be formed based on a coating method.

Example 1 relates to a light-emitting device of the present disclosure. The light-emitting device of the example is composed of a surface-emitting laser element (vertical cavity laser, VCSEL) that emits laser light. A schematic partial end view of the light-emitting device of Example 1 is shown in FIG. 1. In the figure, the Z axis indicates the axis of the first light-reflecting layer 41 constituting the light-emitting device (a perpendicular line to the laminated structure 20 that passes through the center of the first light-reflecting layer 41). The X axis is also perpendicular to the Z axis, and the Y axis is perpendicular to the X axis and the Y axis.

The light emitting device 10A of Example 1 or the light emitting devices of Examples 2 to 11 described below,
a first compound semiconductor layer 21 having a first surface 21a and a second surface 21b opposite to the first surface 21a;
an active layer (light emitting layer) 23 facing the second surface 21b of the first compound semiconductor layer 21; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposed to the first surface;
A laminated structure 20 in which
A first light reflecting layer 41 formed on the first surface side of the first compound semiconductor layer 21;
A second light reflecting layer 42 formed on the second surface side of the second compound semiconductor layer 22;
a first electrode 31 electrically connected to the first compound semiconductor layer 21; and
a second electrode 32 provided between the second compound semiconductor layer 22 and the second light reflecting layer 42;
Equipped with
The second electrode 32 has at least a nano-carbon material layer or a two-dimensional material layer.

The second electrode 32 specifically has a single layer of a nanocarbon material layer or a two-dimensional material layer. Alternatively, the second electrode 32 has a laminated structure of at least a first layer 32A made of a transparent conductive material or a semiconductor material (specifically, a transparent conductive material such as ITO in Example 1) and a second layer 32B made of a nanocarbon material layer or a two-dimensional material layer. In this case, the first layer 32A is in contact with the second surface 22b of the second compound semiconductor layer 22. The thickness of the nanocarbon material layer or the two-dimensional material layer constituting the second electrode 32 is not limited, but is preferably more than 0 nm and 5 nm or less. In Example 1, the nanocarbon material layer constituting the second electrode 32 specifically consists of a graphene layer.

At least a portion of the second compound semiconductor layer 22 in the thickness direction is composed of a current injection region 51 and a current non-injection region 52 surrounding the current injection region 51,
The diameter R _CC of the current injection region 51 in the second surface of the second compound semiconductor layer 22 is, but is not limited to, 1×10 ⁻⁶ m to 1×10 ⁻² m, preferably 2×10 ⁻⁶ m to 1×10 ⁻³ m.

Furthermore, in the light emitting device 10A of Example 1, the first light reflecting layer 41 has a convex shape facing away from the active layer 23, and the second light reflecting layer 42 has a flat shape. The radius of curvature _R1 of the portion of the first light reflecting layer 41 having a convex shape is, but is not limited to, 1×10 ⁻⁵ m to 1×10 ⁻² m, and the cavity length L _OR is, but is not limited to, 1×10 ⁻⁶ m to 5×10 ⁻⁴ m.

The first surface 21a of the first compound semiconductor layer 21 constitutes the base surface 90. The first light reflecting layer 41 is formed on the base surface 90. The base surface 90 has a convex shape facing away from the active layer 23. The portion of the base surface 90 having a convex shape is a first portion 91, and a second portion 92 corresponding to the region between the first portion 91 and the first portion 91 is flat. Alternatively, the second portion 92 corresponding to the peripheral region of the first portion 91 is flat. The second portion 92 surrounds the first portion 91.

When the light-emitting element array is composed of a plurality of juxtaposed light-emitting elements of Example 1 or various other examples described later, the formation pitch of the light-emitting elements 10A in the light-emitting element array is desirably 3 μm or more and 50 μm or less, preferably 5 μm or more and 30 μm or less, and more preferably 8 μm or more and 25 μm or less. The radius of curvature R ₁ of the base surface 90 is desirably 1×10 ⁻⁴ m or more. The arrangement of the light-emitting elements in the light-emitting element array is shown in FIG. 11 and FIG. 12, and will be described in detail in Example 5.

The laminated structure 20 may be configured to be made of at least one material selected from the group consisting of GaN-based compound semiconductors, InP-based compound semiconductors, and GaAs-based compound semiconductors.

Below, an example of the configuration of the light-emitting element 10A of Example 1 is described.

The first compound semiconductor layer 21 is, for example, an n-GaN layer doped with Si at about 2×10 ¹⁶ cm ⁻³ , the active layer 23 is a quintuple quantum well structure in which an In _0.04 Ga _0.96 N layer (barrier layer) and an In _0.16 Ga _0.84 N layer (well layer) are stacked, and the second compound semiconductor layer 22 is, for example, a p-GaN layer doped with magnesium at about 1×10 ¹⁹ cm ⁻³ . The plane orientation of the first compound semiconductor layer 21 is not limited to the {0001} plane, and may be, for example, a {20-21} plane, which is a semipolar plane. The first electrode 31 made of Ti/Pt/Au is electrically connected to an external circuit or the like via a first pad electrode (not shown) made of, for example, Ti/Pt/Au or V/Pt/Au. On the other hand, the second electrode 32 is formed on the second compound semiconductor layer 22, and the second light reflecting layer 42 is formed on the second electrode 32. The second light reflecting layer 42 on the second electrode 32 has a flat shape. A second pad electrode (not shown) made of, for example, Ti/Pt/Au, Ni/Pt/Au, Pd/Ti/Pt/Au, Pd/Ti/Pt/Au, Ti/Pd/Au, or Ti/Ni/Au may be formed or connected on the edge of the second electrode 32 for electrical connection to an external circuit or the like. The first light reflecting layer 41 and the second light reflecting layer 42 are made of a laminated structure of a _{Ta2O5 layer} and a _SiO2 layer, or a laminated structure of a SiN layer and a _SiO2 layer. Although the first light reflecting layer 41 and the second light reflecting layer 42 have a multi-layer structure as described above, they are shown as one layer to simplify the drawing. The opening 31' provided in the first electrode 31, the first light reflecting layer 41, the second light reflecting layer 42, the opening 34A provided in the insulating layer (current confinement layer) 34, and the current injection region 51 each have a circular planar shape. The first compound semiconductor layer 21 has a first conductivity type (specifically, n-type), and the second compound semiconductor layer 22 has a second conductivity type (specifically, p-type) different from the first conductivity type.

The laminated structure 20 has a current injection region 51 and a non-current injection region 52 surrounding the current injection region 51. Here, in the example shown in FIG. 1, the non-current injection region 52 is formed in the thickness direction from the second compound semiconductor layer 22 to a part of the first compound semiconductor layer 21. However, the non-current injection region 52 may be formed in the second electrode side region of the second compound semiconductor layer 22 in the thickness direction, may be formed in the entire second compound semiconductor layer 22, or may be formed in the second compound semiconductor layer 22 and the active layer 23. The non-current injection region 52 can be formed based on an ion implantation method in which, for example, impurities [for example, at least one type of ion (i.e., one type of ion or two or more types of ions) selected from the group consisting of boron, proton, phosphorus, arsenic, carbon, nitrogen, fluorine, oxygen, germanium, zinc, and silicon] are ion-implanted, and a current confinement region consisting of a region with reduced conductivity can be obtained.

3, in order to obtain a current confinement region 52, an insulating layer (current confinement layer) 34 made of an insulating material (e.g., _SiOx , _SiNx , _AlOx ) may be formed between the second electrode 32 and the second compound semiconductor layer 22, and an opening 34A for injecting a current into the second compound semiconductor layer 22 is provided in the insulating layer (current confinement layer) 34. That is, the second compound semiconductor layer 22 is partitioned into a first region 22A and a second region 22B surrounding the first region 22A, a second electrode 32 is provided on the first region 22A of the second compound semiconductor layer 22, and the second region 22B of the second compound semiconductor layer 22 faces the second electrode 32 via the insulating layer 34.

Alternatively, to obtain the current confinement region, the second compound semiconductor layer 22 may be etched by RIE or the like to form a mesa structure, or at least a portion of the stacked second compound semiconductor layer 22 may be partially oxidized laterally to form the current confinement region. Alternatively, the current confinement region may be formed by irradiating the second surface of the second compound semiconductor layer with plasma (specifically, argon, oxygen, nitrogen, etc.), or by ashing the second surface of the second compound semiconductor layer, or by reactive ion etching (RIE) the second surface of the second compound semiconductor layer. By irradiating the second surface of the second compound semiconductor layer with plasma, the conductivity of the second compound semiconductor layer is deteriorated, and the non-current injection region becomes in a high resistance state.

Alternatively, these may be combined as appropriate. However, the second electrode 32 must be electrically connected to the portion of the second compound semiconductor layer 22 through which current flows due to current confinement (current injection region).

The second electrode 32 is connected to an external circuit or the like via a second pad electrode (not shown). The first electrode 31 is also connected to an external circuit or the like via a first pad electrode (not shown). Light may be emitted to the outside via the first light reflecting layer 41, or light may be emitted to the outside via the second light reflecting layer 42.

Various specifications of the light-emitting element 10A of Example 1 are shown in Tables 1, 2, 3, 4, and 5 below.

<Table 1>
Second light reflecting layer 42 _SiO2 / _Ta2O5 (7 _pairs )
Second electrode 32 Graphene (thickness: 3 atomic layers)
Second compound semiconductor layer 22 p-GaN (thickness: 120 nm)
Active layer 23: Multiple quantum well structure (total thickness: 30 nm)
Well layer: InGaN
Barrier layer GaN
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (15 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 450 nm
Radius of curvature _R1 1mm
Current injection region: Formed by ion implantation of boron ions into the second compound semiconductor layer (diameter R _CC : 0.1 mm).
Substrate for manufacturing light-emitting elements GaN substrate [main surface: (0001) surface]

<Table 2>
Second light reflecting layer 42 _SiO2 / _Ta2O5 (7 _pairs )
Second electrode 32
Second layer: Graphene (thickness: 3 atomic layers)
First layer: ITO (thickness: 5 nm)
Second compound semiconductor layer 22 p-GaN (thickness: 110 nm)
Active layer 23: Multiple quantum well structure (total thickness: 30 nm)
Well layer: InGaN
Barrier layer GaN
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (15 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 450 nm
Radius of curvature _R1 1mm
Current injection region: Formed by ion implantation of boron ions into the second compound semiconductor layer (diameter R _CC : 0.1 mm).
Substrate for manufacturing light-emitting element GaN substrate [Main surface: (20-21) surface]

<Table 3>
Second light reflecting layer 42 SiO ₂ /SiN (6 pairs)
Second electrode 32
Second layer: Boron nitride (thickness: 3 atomic layers)
First layer: ITO (thickness: 5 nm)
Second compound semiconductor layer 22 p-GaN (thickness: 150 nm)
Active layer 23: Multiple quantum well structure (total thickness: 30 nm)
Well layer: InGaN
Barrier layer GaN
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (15 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 525 nm
Radius of curvature _R1 1mm
Current injection region: Formed by ion implantation of boron ions into the second compound semiconductor layer (diameter R _CC : 0.1 mm).
Substrate for manufacturing light-emitting element GaN substrate [Main surface: (20-21) surface]

Table 4
Second light reflecting layer 42 SiO ₂ /SiN (6 pairs)
Second electrode 32
Second layer: Molybdenum sulfide (thickness: 20 atomic layers)
First layer: ITO (thickness: 5 nm)
Second compound semiconductor layer 22 p-GaN (thickness: 150 nm)
Active layer 23: Multiple quantum well structure (total thickness: 30 nm)
Well layer: InGaN
Barrier layer GaN
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Nb2O5 (10 _pairs )

Resonator length L _OR 15μm
Oscillation wavelength (emission wavelength) λ ₀ 525 nm
Radius of curvature _R1 2 mm
Current injection region: Formed by ion implantation of boron ions into the second compound semiconductor layer (diameter R _CC : 0.5 mm).
Substrate for manufacturing light-emitting element GaN substrate [Main surface: (20-21) surface]

Table 5
Second light reflecting layer 42 _SiO2 / _Nb2O5 (5 _pairs )
Second electrode 32 Graphene (thickness: 10 atomic layers)
Second compound semiconductor layer 22 p-GaN (thickness: 130 nm)
Active layer 23: Multiple quantum well structure (total thickness: 15 nm)
Well layer: InGaN
Barrier layer GaN
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 SiO ₂ /HfO ₂ (15 pairs)

Resonator length L _OR 15μm
Oscillation wavelength (emission wavelength) λ ₀ 405 nm
Radius of curvature _R1 5mm
Current injection region: Formed by ion implantation of aluminum ions into the second compound semiconductor layer (diameter R _CC : 1 mm).
Substrate for manufacturing light-emitting elements GaN substrate [main surface: (0001) surface]

Below, an overview of the manufacturing method for the light-emitting element 10A of Example 1 is provided.

First, the laminated structure 20 is formed, and then a second light reflecting layer 42 is formed on the second surface side of the second compound semiconductor layer 22.

[Step-100]
Specifically, on the second surface 11b of the compound semiconductor substrate 11 having a thickness of about 0.4 mm,
a first compound semiconductor layer 21 having a first surface 21a and a second surface 21b opposite to the first surface 21a;
an active layer (light emitting layer) 23 facing the second surface 21b of the first compound semiconductor layer 21; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposed to the first surface;
More specifically, the first compound semiconductor layer 21, the active layer 23, and the second compound semiconductor layer 22 are sequentially formed on the second surface 11b of the compound semiconductor substrate 11 based on an epitaxial growth method using a well-known MOCVD method, thereby obtaining the stacked structure 20 (see FIG. 32A ).

[Step-110]
Next, a current non-injection region 52 is formed in the stacked structure 20 based on a well-known ion implantation method using boron ions (see FIG. 32B).

[Step-120]
Thereafter, a second electrode 32 is formed on the second compound semiconductor layer 22. Specifically, for example, a rolled copper foil (corresponding to a support member) having a thickness of 35 μm is heated to 1000° C. in a hydrogen atmosphere (hydrogen flow rate 20 sccm) in an electric furnace, and methane gas is supplied at a flow rate of 30 sccm for 30 minutes to form a graphene layer on the copper foil. Next, an acetone diluted solution of methyl methacrylate (PMMA) is applied on the graphene layer by spin coating, and the solution is dried to form a PMMA film. Thereafter, the copper foil (support member) is removed using an aqueous iron nitrate solution, leaving the graphene layer bonded to the PMMA film. Then, the graphene layer is transferred onto the second surface 22b of the second compound semiconductor layer 22, and the PMMA film is removed using an acetone solvent. In this way, a second electrode 32 made of a graphene layer can be obtained on the second surface 22b of the second compound semiconductor layer 22. Furthermore, if desired, a second pad electrode is formed on the second electrode 32 based on a combination of a film formation method such as a sputtering method or a vacuum deposition method and a patterning method such as a wet etching method or a dry etching method.

[Step-130]
Next, the second light reflecting layer 42 is formed on the second electrode 32. Specifically, the second light reflecting layer 42 is formed from above the second electrode 32 to above the second pad electrode based on a combination of a film forming method such as a sputtering method or a vacuum deposition method and a patterning method such as a wet etching method or a dry etching method. The second light reflecting layer 42 on the second electrode 32 has a flat shape. In this manner, the structure shown in FIG. 33 can be obtained.

[Step-140]
Next, the second light reflecting layer 42 is fixed to a support substrate 49 via a bonding layer 48 (see FIG. 34). Specifically, the second light reflecting layer 42 is fixed to a support substrate 49 made of a sapphire substrate by using the bonding layer 48 made of an adhesive.

[Step-150]
Next, the compound semiconductor substrate 11 is thinned by mechanical polishing or CMP, and further, the compound semiconductor substrate 11 is removed by etching.

[Step-160]
Thereafter, a sacrificial layer 81 is formed on a region of the base surface 90 (specifically, the first surface 21a of the first compound semiconductor layer 21) where the first portion 91 of the base surface 90 is to be formed, and then the surface of the sacrificial layer 81 is made convex. Specifically, a resist material layer is formed on the first surface 21a of the first compound semiconductor layer 21, and the resist material layer is patterned so as to remain on the region of the base surface 90 where the first portion 91 is to be formed (see FIG. 35A), and then the remaining resist material layer is subjected to a heat treatment, thereby obtaining a sacrificial layer 81' having a convex surface (see FIG. 35B). Next, the sacrificial layer 81' is etched back, and further etched back from the base surface 90 toward the inside (i.e., from the first surface 21a of the first compound semiconductor layer 21 to the inside of the first compound semiconductor layer 21), thereby forming a convex portion in the first portion 91 of the base surface 90 when the second surface 21b of the first compound semiconductor layer 21 is used as a reference (see FIG. 35C). A second portion 92 corresponding to a region between the first portions 91 of the base surface 90 is flat. The etch back can be performed based on a dry etching method such as an RIE method, or based on a wet etching method using hydrochloric acid, nitric acid, hydrofluoric acid, phosphoric acid, a mixture of these, or the like. Note that the active layer, the second compound semiconductor layer, the second light reflecting layer, and the like are omitted from illustration in Figures 35A, 35B, and 35C.

[Step-170]
Next, the first light reflecting layer 41 is formed on the convex portion 91 of the base surface 90. Specifically, the first light reflecting layer 41 is formed on the entire surface of the base surface 90 based on a film forming method such as a sputtering method or a vacuum deposition method, and then the first light reflecting layer 41 is patterned to obtain the first light reflecting layer 41 on the convex portion 91 of the base surface 90. Then, the first electrode 31 is formed on the area of the base surface 90 where the first light reflecting layer 41 is not formed. In this manner, the light emitting element 10A of the first embodiment shown in FIG. 1 can be obtained. If the first electrode 31 is made to protrude from the first light reflecting layer 41, the first light reflecting layer 41 can be protected. Then, it is sufficient to electrically connect it to an external electrode or circuit (a circuit that drives the light emitting element). Specifically, the first compound semiconductor layer 21 is connected to an external circuit or the like via the first electrode 31 and a first pad electrode (not shown), and the second compound semiconductor layer 22 is connected to an external circuit or the like via the second electrode 32 and a second pad electrode. Next, the light emitting element 10A of the first embodiment is completed by packaging and sealing.

2 is a schematic partial end view of Modification 1 of the light-emitting element 10A of Example 1. In step 120, a second electrode 32 having a laminated structure of a first layer 32A made of a transparent conductive material such as ITO and a second layer 32B made of a nanocarbon material layer or the like may be formed on the second surface 22b of the second compound semiconductor layer 22. In this case, the first layer 32A is in contact with the second compound semiconductor layer 22.

In order to control the polarization state of the light emitted from the light-emitting element 10A, the second electrode 32, more specifically, the second electrode 32 composed of a first layer and a second layer, may have a plurality of grooves formed in the second layer extending in one direction (e.g., a first direction, the Y direction).

In addition, in [Step-110], an insulating layer (current confinement layer) 34 made of an insulating material (e.g., _SiOx , _SiNx , _AlOx ) may be formed between the second electrode 32 and the second compound semiconductor layer 22 to obtain a current non-injection region 52, and an opening 34A for injecting a current into the second compound semiconductor layer 22 is provided in the insulating layer (current confinement layer) 34. A schematic partial end view of Modification-2 of the light-emitting element 10A having such a structure is shown in FIG. 3. The current confinement region (current non-injection region 52) is defined by the insulating layer 34 having the opening 34A. That is, the current injection region 51 is defined by the opening 34A.

In the light-emitting element of Example 1, since the second electrode has a nanocarbon material layer or the like, the resistance of the second electrode as a whole can be reduced, and it is possible to uniformly pass current through the active layer, and the occurrence of a non-uniform state of current flowing from the periphery to the center of the second electrode can be suppressed. Therefore, it is possible to suppress the occurrence of problems such as a shortage of current flowing through the center of the current injection region, which inhibits oscillation and increases the threshold current, and oscillation at a lower threshold current is possible. In addition, it is possible to prevent the oscillation in the transverse mode from becoming unstable. As a result of the above, it is possible to expand the area of the active layer (light-emitting layer), and a light-emitting element with a large light output can be provided.

In addition, in the light-emitting device of Example 1, the first light reflecting layer functions as a concave mirror, so that the light diffracts and spreads from the active layer as a starting point, and the light incident on the first light reflecting layer can be reliably reflected toward the active layer and focused on the active layer. Therefore, it is possible to avoid an increase in diffraction loss, reliably perform laser oscillation, and since it has a long resonator, it is possible to avoid the problem of thermal saturation. In addition, since the resonator length can be made long, the tolerance of the manufacturing process of the light-emitting device is increased, and the yield can be improved. In addition, "diffraction loss" generally refers to the phenomenon in which light tends to spread due to the diffraction effect, and the laser light traveling back and forth through the resonator gradually dissipates outside the resonator.

In addition, in the manufacturing process of the light-emitting element, a GaN substrate is used, but a GaN-based compound semiconductor is not formed based on a method of lateral epitaxial growth such as the ELO method. Therefore, as the GaN substrate, not only a polar GaN substrate but also a semi-polar GaN substrate or a non-polar GaN substrate can be used. When a polar GaN substrate is used, the light-emitting efficiency tends to decrease due to the effect of the piezoelectric field in the active layer, but if a non-polar GaN substrate or a semi-polar GaN substrate is used, it is possible to solve or alleviate such a problem.

4 is a schematic partial end view of the modified example 3 of the light emitting element 10A of the first embodiment, the second electrode 32 has a laminated structure of a first layer 32A and a second layer 32B, and the second layer 32B is not formed in the center of the second electrode 32, thereby suppressing the emission of light in a higher mode from the light emitting element 10A. A transparent thin film (flattening film) 32C made of ITO may be formed in the region in the center of the second electrode 32 where the second layer 32B is not formed. The light generated in the active layer 23 and passing through the transparent thin film 32C is not absorbed in the transparent thin film 32C. On the other hand, the second layer 32B surrounding the transparent thin film 32C absorbs the light generated in the active layer 23. Specifically, in such a light emitting element 10A, the distance L ₂ from the center of the active layer 23 in the thickness direction of the laminated structure 20 to the center of the second layer 32B in the thickness direction does not satisfy the above-mentioned formula (A). As a result, the second layer 32B is not located in the minimum amplitude portion of the light intensity distribution, and the second layer 32B can easily absorb the light generated in the active layer 23. That is, light having a higher-order transverse mode is easily absorbed by the second layer 32B, while light having a first-order transverse mode passes through the transparent thin film 32C, making it possible to control the transverse mode laser light emitted from the light-emitting element 10A. In this way, it is possible to accurately control the oscillation wavelength of the laser light emitted from the surface-emitting laser element, and the light-emitting efficiency of the light-emitting element 10A can be improved. The relationship between the diameter R _CL and the diameter R _CC of the area in the center of the second electrode 32 where the second layer 32B is not formed is given by
0.05R _CC <R _CL <0.95R _CC
Examples of the specifications of such a light-emitting device are shown in Table 5. However, the second electrode 32 [graphene (thickness: 10 atomic layers)] is a doughnut-shaped second electrode 32 with a diameter of about 100 μm removed from the center. That is, the diameter R _CL is set to 100 μm. Alternatively, the specifications of such a light-emitting device are shown in Table 6 (described later).

On the other hand, in any of the specifications shown in Tables 1 to 5, in the light emitting device 10A, the distance L ₂ from the center of the active layer 23 in the thickness direction of the laminated structure 20 to the center of the nanocarbon material layer, etc. in the thickness direction satisfies the above-mentioned formula (A). This makes it possible to position the nanocarbon material layer, etc. constituting the second electrode 32 in the minimum amplitude part of the light intensity distribution, that is, as a result of positioning the nanocarbon material layer, etc. in the minimum amplitude part generated in the standing wave of light formed inside the light emitting device 10A, the nanocarbon material layer, etc. constituting the second electrode 32 becomes difficult to absorb the light generated in the active layer 23, the light emission efficiency of the light emitting device 10A can be improved, and the oscillation wavelength of the laser light emitted from the surface emitting laser element can be accurately controlled. The optical absorption coefficient of the nanocarbon material layer is more than twice the optical absorption coefficient of the second compound semiconductor layer 22 made of a p-GaN layer, specifically, about 1×10 ³ times. The active layer 23 is located in the maximum amplitude part generated in the standing wave of light formed inside the light emitting device 10A.

When multiple longitudinal modes occur within the gain spectrum determined by the active layer 23, this is shown in FIG. 45. In FIG. 45, two longitudinal modes, longitudinal mode A and longitudinal mode B, are illustrated. In this case, the light absorbing material layer 26 is located in the minimum amplitude portion of longitudinal mode A and is not located in the minimum amplitude portion of longitudinal mode B. In this case, the mode loss of longitudinal mode A is minimized, but the mode loss of longitudinal mode B is large. In FIG. 45, the mode loss of longitudinal mode B is shown by a solid line. Therefore, longitudinal mode A is easier to oscillate than longitudinal mode B. Therefore, by using such a structure, that is, by controlling the position of the light absorbing material layer 26, a specific longitudinal mode can be stabilized and made easier to oscillate. On the other hand, since the mode loss for undesirable other longitudinal modes can be increased, it is possible to suppress the oscillation of undesirable other longitudinal modes.

Therefore, by controlling the position of the nano-carbon material layer or the like that functions as the light absorbing material layer 26 in this manner, it is possible to suppress the oscillation of laser light of an undesired longitudinal mode among the multiple types of longitudinal mode laser light that can be emitted from the surface emitting laser element. As a result, it is possible to accurately control the oscillation wavelength of the emitted laser light.

For example, at least two layers, preferably at least four layers, of the light absorbing material layer 26 described above may be arranged so as to satisfy the formula (A) of the first compound semiconductor layer 21. That is, it is preferable that the light absorbing material layer 26 is located in the minimum amplitude portion of the standing wave of light formed inside the stacked structure 20. In addition, the thickness of the light absorbing material layer 26 is preferably λ ₀ /(4·n _eq ) or less. An example of the lower limit of the thickness of the light absorbing material layer 26 is 1 nm. It is preferable that the light absorbing material layer 26 has a light absorption coefficient that is at least twice the light absorption coefficient of the compound semiconductor constituting the stacked structure 20.

The light absorbing material layer 26 may be configured to be composed of at least one material selected from the group consisting of compound semiconductor materials, impurity-doped compound semiconductor materials, transparent conductive materials, and light reflecting layer constituent materials having light absorbing properties. Here, as a compound semiconductor material having a narrower band gap than the compound semiconductor constituting the laminated structure 20, for example, when the compound semiconductor constituting the laminated structure 20 is GaN, InGaN may be cited. As a compound semiconductor material doped with impurities, n-GaN doped with Si and n-GaN doped with B may be cited. As a light reflecting layer constituent material having light absorbing properties, a material constituting the light reflecting layer (e.g., SiO _x , SiN _x , TaO _x , etc.) may be cited. All of the light absorbing material layers 26 may be composed of one type of material among these materials. Alternatively, each of the light absorbing material layers 26 may be composed of various materials selected from these materials, but it is preferable that one light absorbing material layer 26 is composed of one type of material from the viewpoint of simplifying the formation of the light absorbing material layer 26. The light absorbing material layer 26 may be formed in the first compound semiconductor layer 21, may be formed in the second compound semiconductor layer 22, may be formed in the first light reflecting layer 41, may be formed in the second light reflecting layer 42, or any combination of these may be used. A schematic partial end view of a light emitting element (Modification 4 of Example 1) in which one light absorbing material layer 26 is formed in the first compound semiconductor layer 21 is shown in FIG.

The light-emitting element of Example 1 or various modified examples thereof can be applied to the light-emitting elements of Examples 2 to 3.

Example 2 is a modification of Example 1. In Example 1, the stacked structure 20 is made of a GaN-based compound semiconductor. On the other hand, in Example 2, the stacked structure 20 is made of an InP-based compound semiconductor. Specifically, the first compound semiconductor layer 21 is made of n-InP doped with Se at 1×10 ¹⁸ cm ⁻³ , the active layer 23 is made of an AlGaInAs layer, and the second compound semiconductor layer 22 is made of a p-AlGaInAs layer doped with C (carbon) at 1×10 ¹⁹ cm ⁻³ . The current non-injection region 52 is made of a stacked structure of n-AlGaInAs layer/p-AlGaInAs layer/n-InP layer, or an Fe-doped InP layer, or is formed based on an ion implantation method. The configuration of the second electrode 32 is the same as that described in Example 1. Furthermore, in the light-emitting device of Example 2 as a modified example of Example 2, the first light reflecting layer 41 is formed on a semi-insulating InP substrate (undoped or doped with Fe) as a substrate for manufacturing the light-emitting device. Except for the above points, the light-emitting device of Example 2 can have the same configuration and structure as the light-emitting device of Example 1, so detailed description will be omitted.

The specifications of the light-emitting element of Example 2 are shown in Table 6 below.

Table 6
Second light reflecting layer 42 _SiO2 / _Ta2O5 (7 _pairs )
Second electrode 32 Graphene (thickness: 3 atomic layers)
Second compound semiconductor layer 22 p-InP (thickness: 200 nm)
Active layer 23: Multiple quantum well structure (total thickness: 40 nm)
Well layer: AlGaInAs
Barrier layer: AlGaInAs
First compound semiconductor layer 21 n-InP
First light reflecting layer 41 _SiO2 / _Ta2O5 (15 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 1400 nm
Radius of curvature _R1 1mm
Current injection region: Formed by ion implantation of hydrogen ions into the second compound semiconductor layer (diameter R _CC : 0.1 mm).
Substrate for manufacturing light-emitting devices InP substrate

Alternatively, in Example 2, the stacked structure 20 can be made of a GaAs-based compound semiconductor. The specifications of such a modified example of the light-emitting element of Example 2 are shown in Table 7 below.

Table 7
Second light reflecting layer 42 _SiO2 / _Ta2O5 (7 _pairs )
Second electrode 32 Graphene (thickness: 3 atomic layers)
Second compound semiconductor layer 22 p-AlGaAs (thickness: 200 nm)
Active layer 23: Multiple quantum well structure (total thickness: 40 nm)
Well layer: InGaAs
Barrier layer: AlGaAs
First compound semiconductor layer 21 n-AlGaAs
First light reflecting layer 41 _SiO2 / _Ta2O5 (15 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ approx. 900 nm
Radius of curvature _R1 1mm
Current injection region: Formed by ion implantation of hydrogen ions into the second compound semiconductor layer (diameter R _CC : 0.1 mm).
Substrate for manufacturing light emitting devices GaAs substrate

Example 3 is a modification of Examples 1 and 2. In the light-emitting device 10B of Example 3, a schematic partial end view of which is shown in Figure 6, the compound semiconductor substrate 11 is disposed (remained) between the first surface 21a of the first compound semiconductor layer 21 and the first light reflecting layer 41, and the base surface 90 is composed of the surface (first surface 11a) of the compound semiconductor substrate 11. Note that, although Figure 6 illustrates a light-emitting device based on the light-emitting device of Modification 2 of Example 1, the present invention is not limited to this.

In the light-emitting element 10B of Example 3, the compound semiconductor substrate 11 is thinned and mirror-finished in the same process as [Step-150] of Example 1. The surface roughness Ra of the first surface 11a of the compound semiconductor substrate 11 is preferably 10 nm or less. The surface roughness Ra is specified in JIS B-610:2001, and can be measured based on observation using an AFM or a cross-sectional TEM. Thereafter, a sacrificial layer in [Step-160] of Example 1 is formed on the exposed surface (first surface 11a) of the compound semiconductor substrate 11, and the same processes as those after [Step-160] of Example 1 are performed, and a base surface 90 consisting of a first portion 91 and a second portion 92 is provided on the compound semiconductor substrate 11 instead of the first compound semiconductor layer 21 in Example 1, thereby completing the light-emitting element. The first electrode 31 may be formed on the compound semiconductor substrate 11.

Except for the above points, the configuration and structure of the light-emitting element in Example 3 can be similar to the configuration and structure of the light-emitting element in Examples 1 and 2, so a detailed description will be omitted.

Alternatively, the first light reflecting layer 41 may be formed on a sapphire substrate as a substrate for manufacturing a light emitting element. In this case, the first electrode 31 may be connected to the first compound semiconductor layer 21 in a region not shown.

Example 4 is also a modification of Examples 1 and 2. In a light-emitting device 10C of Example 4, a schematic partial end view of which is shown in FIG. 7, a base material 95 is disposed between the first surface 21a of the first compound semiconductor layer 21 and the first light reflecting layer 41, and the base surface 90 is constituted by the surface of the base material 95. Alternatively, in a modification of the light-emitting device 10C of Example 4, a schematic partial end view of which is shown in FIG. 8, a compound semiconductor substrate 11 and a base material 95 are disposed between the first surface 21a of the first compound semiconductor layer 21 and the first light reflecting layer 41, and the base surface 90 is constituted by the surface of the base material 95. Examples of materials constituting the base material 95 include transparent dielectric materials such as TiO ₂ , Ta ₂ O ₅ , and SiO ₂ , silicone-based resins, and epoxy-based resins. Note that, although FIGS. 7 and 8 show a light-emitting device based on the light-emitting device of Modification-2 of Example 1, the present invention is not limited thereto.

In the light-emitting device 10C of Example 4 shown in FIG. 7, the compound semiconductor substrate 11 is removed in the same step as [Step-150] of Example 1, and a base material 95 having a base surface 90 is formed on the first surface 21a of the first compound semiconductor layer 21. Specifically, for example, a TiO ₂ layer or a Ta ₂ O ₅ layer is formed on the first surface 21a of the first compound semiconductor layer 21, and then a patterned resist layer is formed on the TiO ₂ layer or Ta ₂ O ₅ layer on which the first portion 91 is to be formed, and the resist layer is heated to reflow the resist layer to obtain a resist pattern. The resist pattern is given the same shape (or a similar shape) as the shape of the first portion. Then, the resist pattern and the TiO ₂ layer or the Ta ₂ O ₅ layer are etched back to obtain a base material 95 (made of a TiO ₂ layer or a Ta ₂ O ₅ layer) on which the first portion 91 and the second portion 92 are provided on the first surface 21a of the first compound semiconductor layer 21. Next, the first light reflecting layer 41 may be formed on the desired area of the base material 95 by a known method.

Alternatively, in the light-emitting device 10C of Example 4 shown in Fig. 8, the compound semiconductor substrate 11 is thinned and mirror-finished in the same process as [Step-150] of Example 1, and then a base material 95 having a base surface 90 is formed on the exposed surface (first surface 11a) of the compound semiconductor substrate 11. Specifically, for example, a _TiO2 layer or a _Ta2O5 layer is formed on the exposed surface (first surface _11a ) of the compound semiconductor substrate 11, and then a patterned resist layer is formed on the _TiO2 layer or _{the Ta2O5} layer on which the first portion 91 is to be formed, and the resist layer is heated to reflow the resist layer, thereby obtaining a resist pattern. The resist pattern is given the same shape (or a similar shape) as the shape of the first portion. Then, the resist pattern and the TiO2 layer or the _Ta2O5 layer are etched back to obtain a base material 95 (made of _{a TiO2} layer or a _Ta2O5 layer) having a first portion 91 and a second portion 92 provided on the exposed surface (first surface _11a ) of the compound _{semiconductor} substrate 11. Next, a first light reflecting layer 41 may be formed on a desired region of the base material 95 based on a known method.

Except for the above points, the configuration and structure of the light-emitting element in Example 4 can be similar to the configuration and structure of the light-emitting element in Examples 1 and 2, so a detailed explanation will be omitted.

However, in the light-emitting element described in Examples 1 to 4, if a strong external force is applied to the rising portion of the first portion 91 of the flat base surface 90 for some reason, stress will be concentrated in the rising portion of the first portion 91, and there is a risk of damage being caused to the first compound semiconductor layer, etc.

Example 5 is a modification of Examples 1 to 4. A schematic partial end view of the light-emitting element 10D of Example 5 is shown in Figure 9, and a schematic partial end view of a light-emitting element array including a plurality of the light-emitting elements 10D of Example 5 is shown in Figure 10. Also, schematic partial end views of the first compound semiconductor layer and the like for explaining the manufacturing method of the light-emitting element of Example 5 are shown in Figures 35A, 35B, 36A, 36B, 36C, 37A, 37B, 37C, 38A, and 38B.

In addition, in Figures 36A, 36B, 36C, 37A, 37B, 37C, 38A, 38B, 39A, 39B, 40A, 40B, 41A, 41B, 42A, 42B, and 42C, the active layer, the second compound semiconductor layer, the second light reflecting layer, and the like are omitted. In addition, in Figures 11, 12, 15, 16, 17, 18, 21, and 22, the first portion of the base surface is shown as a solid circle or ellipse for clarity, the center of the second portion of the base surface is shown as a solid circle for clarity, and the top portion of the annular convex shape of the second portion of the base surface is shown as a solid ring for clarity.

In the light-emitting element 10D of Example 5, the first light reflecting layer 41 is
A base surface 90 located on the first surface side of the first compound semiconductor layer 21 is composed of a first portion 91 and a second portion 92 (peripheral region 99) surrounding the first portion 91,
The first light reflecting layer 41 is formed on the first portion 91,
With respect to the second surface 21b of the first compound semiconductor layer 21 as a reference, the first portion 91 is convex and the second portion 92 is concave, and differentiable from the first portion 91 to the second portion 92. The light-emitting device 10D shown in Figs. 9 and 10 is a light-emitting device to which Modification 2 of Example 1 is applied.

Here, when the base surface 90 is expressed as z=f(x, y), the differential value at the base surface 90 is expressed as follows:
∂z/∂x=[∂f(x,y)/∂x] _y
∂z/∂y=[∂f(x,y)/∂y] _x
"Smooth" is a term used in analysis. For example, if a real variable function f(x) is differentiable in the range a<x<b and f'(x) is continuous, it can be said to be continuously differentiable, or expressed as smooth. The portion of the base surface 90 that extends from the first portion 91 to the second portion 92 where an inflection point exists is the boundary between the first portion 91 and the second portion 92.

As described above, when the second surface 21b of the first compound semiconductor layer 21 is used as a reference, the second portion 92 of the base surface 90 occupying the peripheral region 99 has a downwardly convex shape. A light-emitting element having such a configuration is called a "light-emitting element of A-th configuration". In a light-emitting element array having a plurality of light-emitting elements of A-th configuration, the center of the first portion 91 of the base surface 90 can be configured to be located on the apex (intersection) of a square lattice, or the center of the first portion 91 of the base surface 90 can be configured to be located on the apex (intersection) of an equilateral triangular lattice. In the former case, the center of the second portion 92 of the base surface 90 can be configured to be located on the apex (intersection) of a square lattice, and in the latter case, the center of the second portion 92 of the base surface 90 can be configured to be located on the apex (intersection) of an equilateral triangular lattice.

In the light-emitting element of the A configuration, the shape of the [first portion/second portion from the peripheral portion to the center portion] is
(A) [Upward convex shape/downward convex shape]
(B) [Continuing from an upward convex shape/downward convex shape to a line segment]
(C) [Upward convex shape/upward convex shape continues into downward convex shape]
(D) [Upward convex shape/Upward convex shape to downward convex shape, continuing to a line segment]
(E) [Upward convex shape/line segment continues into downward convex shape]
(F) [Upward convex shape/Downward convex shape from line segment, continuing to line segment]
In the light emitting element, the base surface may terminate at the center of the second portion. In the light emitting element 10D of Example 5, the shape of [the first portion 91/second portion 92 from the periphery to the center] specifically corresponds to the case (A).

Alternatively, when the second surface 21b of the first compound semiconductor layer 21 is used as a reference, the second portion 92 of the base surface 90 occupying the peripheral region 99 can be configured to have a downwardly convex shape toward the center of the peripheral region 99 and an upwardly convex shape extending from the downwardly convex shape. A light-emitting element having such a configuration is referred to as a "light-emitting element of configuration B." In the light-emitting element of configuration B, when the distance from the second surface 21b of the first compound semiconductor layer 21 to the center of the first portion 91 of the base surface 90 is LL ₁ and the distance from the second surface 21b of the first compound semiconductor layer 21 to the center of the second portion 92 of the base surface 90 is LL ₂ ,
_LL2 > _LL1
In addition, when the radius of curvature of the center of the first portion 91 of the base surface 90 (i.e., the radius of curvature of the first light reflecting layer) is R ₁ and the radius of curvature of the center of the second portion 92 of the base surface 90 is R ₂ ,
_R1 > _R2
The value of _LL2 / _LL1 is not limited to, but may be,
1<LL ₂ /LL ₁ ≦100
Examples of the value of R ₁ /R ₂ include, but are not limited to,
1<R ₁ /R ₂ ≦100
Examples include:

In the light-emitting element having the B-th configuration, the shape of [the first portion 91/the second portion 92 from the peripheral portion to the center portion] is as follows:
(A) [Upward convex shape/downward convex shape continues to upward convex shape]
(B) [Upward convex shape/upward convex shape continues to downward convex shape to upward convex shape]
(C) [Upward convex shape/line segment leading to downward convex shape, then upward convex shape]
There are cases like this.

Alternatively, when the second surface 21b of the first compound semiconductor layer 21 is used as a reference, the second portion 92 of the base surface 90 occupying the peripheral region 99 can be configured to have an annular convex shape surrounding the first portion 91 of the base surface 90, and a downwardly convex shape extending from the annular convex shape toward the first portion 91 of the base surface 90. A light-emitting element having such a configuration is referred to as a "light-emitting element of configuration C."

In the light-emitting device of configuration C, when the distance from the second surface 21b of the first compound semiconductor layer 21 to the center of the first portion 91 of the base surface 90 is defined as LL ₁ and the distance from the second surface 21b of the first compound semiconductor layer 21 to the top of the annular convex shape of the second portion 92 of the base surface 90 is defined as LL ₂ ',
_LL2 '> _LL1
In addition, when the radius of curvature of the center of the first portion 91 of the base surface 90 (i.e., the radius of curvature of the first light reflecting layer) is R ₁ and the radius of curvature of the apex of the annular convex shape of the second portion 92 of the base surface 90 is R ₂ ',
R ₁ >R ₂ '
The value of _LL2 '/ _LL1 is not limited to, but may be,
1< _LL2 '/ _LL1 ≦100
Examples of the value of R ₁ /R ₂ ' include, but are not limited to,
1<R ₁ /R ₂ '≦100
Examples include:

In the light-emitting element of the Cth configuration, the shape of [the first portion 91/the second portion 92 from the peripheral portion to the center portion] is
(A) [Continuing from an upward convex shape/downward convex shape to an upward convex shape/downward convex shape]
(B) [Continuing from an upward convex shape/downward convex shape to an upward convex shape, a downward convex shape, and a line segment]
(C) [Upward convex shape/upward convex shape followed by downward convex shape, upward convex shape, downward convex shape]
(D) [Upward convex shape/upward convex shape to downward convex shape, upward convex shape, downward convex shape, continuing to a line segment]
(E) [Upward convex shape/line segment leading to downward convex shape, upward convex shape, downward convex shape]
(F) [Upward convex shape/Continuing from a line segment to a downward convex shape, upward convex shape, downward convex shape, to a line segment]
In addition, in the light emitting element, the base surface 90 may terminate at the center of the second portion 92.

In the light-emitting device of the B configuration or the C configuration including the preferred configuration described above, a bump can be arranged on the second surface side of the second compound semiconductor layer facing the convex portion in the second portion of the base surface. Alternatively, in the light-emitting device of the A configuration including the preferred configuration described above, a bump can be arranged on the second surface side of the second compound semiconductor layer facing the center of the first portion of the base surface. Examples of the bump include a gold (Au) bump, a solder bump, and an indium (In) bump, and the bump can be arranged by a well-known method. Specifically, the bump is provided on the second pad electrode provided on the second electrode, or on the extension of the second pad electrode.

The light-emitting element 10D of Example 5 is described in detail below.

In the light-emitting element 10D of Example 5, the base surface 90 extends to the peripheral region 99 in the light-emitting elements 10A, 10B, and 10C described in Examples 1 to 4, and the base surface 90 is uneven and differentiable. That is, in the light-emitting element 10D of Example 5, the base surface 90 is analytically smooth. Note that the first light-reflecting layer 41 is formed on the base surface 90 located on the first surface side of the first compound semiconductor layer 21, similar to the light-emitting elements 10A, 10B, and 10C described in Examples 1 to 4, and the second light-reflecting layer 42 is formed on the second surface side of the second compound semiconductor layer 22 and has a flat shape.

When the second surface 21b of the first compound semiconductor layer 21 is used as a reference, the first portion 91 of the base surface 90 on which the first light reflecting layer 41 is formed has an upwardly convex shape, and when the second surface 21b of the first compound semiconductor layer 21 is used as a reference, the second portion 92 of the base surface 90 occupying the peripheral region 99 has a downwardly convex shape and surrounds the first portion 91. A central portion _91c of the first portion 91 of the base surface 90 is located on an apex (intersection) of a square lattice (see, for example, FIG. 11 for the arrangement), or alternatively, the central portion _91c of the first portion 91 of the base surface 90 is located on an apex (intersection) of an equilateral triangular lattice (see, for example, FIG. 12 for the arrangement).

The first light reflecting layer 41 is formed on a first portion 91 of the base surface 90, but an extension of the first light reflecting layer 41 may be formed on a second portion 92 of the base surface 90 occupying the peripheral region 99, or the first light reflecting layer 41 may not be formed on the second portion 92. In Example 5, the first light reflecting layer 41 is not formed on the second portion 92 of the base surface 90 occupying the peripheral region 99.

In the light emitting element 10D of Example 5, the boundary 90 _bd between the first portion 91 and the second portion 92 is
(1) When the first light reflecting layer 41 does not extend to the peripheral region 99, the outer periphery of the first light reflecting layer 41. (2) When the first light reflecting layer 41 extends to the peripheral region 99, the outer periphery can be defined as a portion where an inflection point exists on the base surface 90 from the first portion 91 to the second portion 92. Here, the light emitting element 10D of Example 5 specifically corresponds to the case of (1).

In the light-emitting element 10D of Example 5, the first surface 21a of the first compound semiconductor layer 21 constitutes the base surface 90. The figure drawn by the first portion 91 of the base surface 90 when the base surface 90 is cut by a virtual plane (for example, the XZ plane in the illustrated example) including the stacking direction of the stacked structure 20 is differentiable, and more specifically, it can be a part of a circle, a part of a parabola, a sine curve, a part of an ellipse, or a part of a catenary curve, or a combination of these curves, and some of these curves may be replaced by a line segment. The figure drawn by the second portion 92 is also differentiable, and more specifically, it can be a part of a circle, a part of a parabola, a part of a sine curve, a part of an ellipse, or a part of a catenary curve, or a combination of these curves, and some of these curves may be replaced by a line segment. Furthermore, the boundary between the first portion 91 and the second portion 92 of the base surface 90 is also differentiable.

In the light-emitting element array, the pitch of the light-emitting elements is preferably 3 μm or more and 50 μm or less, preferably 5 μm or more and 30 μm or less, more preferably 8 μm or more and 25 μm or less. The radius of curvature R ₁ of the center 91 _c of the first portion 91 of the base surface 90 is preferably 1×10 ⁻⁴ m or more. The resonator length L _OR preferably satisfies 1×10 ⁻⁶ m≦L _OR . In the light-emitting element array of Example 5, the arrangement of which is shown in FIG. 11 and FIG. 12, the parameters of the light-emitting element 10D are shown in Table 8 below. The diameter of the first light reflecting layer 41 is indicated by D ₁ , the height of the first portion 91 is indicated by H ₁ , and the radius of curvature of the center 92 _c of the second portion 92 of the base surface 90 is indicated by R ₂ . Here, when the distance from the second surface 21 _b of the first compound semiconductor layer 21 to the central portion 91 _c of the first portion 91 of the base surface 90 is defined as LL ₁ , and the distance from the second surface 21 b of the first compound semiconductor layer 21 to the central portion 92 _c of the second portion 92 of the base surface 90 is defined as LL ₂ , the height H 1 of the first portion 91 is expressed as follows:
_H1 = _LL1 - _LL2
The specifications of the light-emitting element 10D of Example 5, the arrangement of which is shown in Fig. 11 and Fig. 12, are shown in the following Tables 9 and 10. Note that the "number of light-emitting elements" refers to the number of light-emitting elements constituting one light-emitting element array.

<Table 8>
See the arrangement in FIG. 11 See the arrangement in FIG. 12 Formation pitch 25 μm 20 μm
Radius of curvature R ₁ 100μm 200μm
Diameter D ₁ 20μm 15μm
Height _H1 2 μm 2 μm
Radius of curvature R ₂ 2μm 3μm

Table 9: See the arrangement in FIG. 11. Second light reflecting layer 42: SiO ₂ /Ta ₂ O ₅ (11.5 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 445 nm
Number of light emitting elements: 100 x 100

Table 10: See the arrangement in FIG. 12. Second light reflecting layer 42: SiO ₂ /SiN (9 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 488 nm
Number of light emitting elements: 1000 x 1000

In the light-emitting element of Example 5, the base surface is uneven and differentiable, so that if a strong external force is applied to the light-emitting element for some reason, the problem of stress concentration on the rising part of the convex part can be reliably avoided, and there is no risk of damage to the first compound semiconductor layer, etc. In particular, in the light-emitting element array, bumps are used to connect and bond to external circuits, etc., but a large load (for example, about 50 MPa) must be applied to the light-emitting element array during bonding. In the light-emitting element array of Example 5, even if such a large load is applied, there is no risk of damage to the light-emitting element array. In addition, because the base surface is uneven, the generation of stray light is further suppressed, and the occurrence of optical crosstalk between light-emitting elements can be more reliably prevented.

When emitting elements are arranged in a light-emitting element array, the footprint diameter of the sacrificial layer described above cannot exceed the formation pitch of the light-emitting elements. Therefore, in order to narrow the formation pitch of the light-emitting element array, it is necessary to reduce the footprint diameter. Incidentally, the radius of curvature R ₁ of the center of the first portion 91 of the base surface 90 has a positive correlation with the footprint diameter. In other words, when the footprint diameter becomes smaller with the narrow formation pitch, the radius of curvature R ₁ tends to become smaller as a result. For example, a radius of curvature R ₁ of about 30 μm has been reported for a footprint diameter of 24 μm. In addition, the radiation angle of light emitted from the light-emitting element has a negative correlation with the footprint diameter. In other words, when the footprint diameter becomes smaller with the narrow formation pitch, the radius of curvature R ₁ becomes smaller and the FFP (Far Field Pattern) tends to expand. With a radius of curvature R ₁ of less than 30 μm, the radiation angle may be several degrees or more. Depending on the application field of the light-emitting element array, a narrow radiation angle of 2 to 3 degrees or less may be required for the light emitted from the light-emitting element.

In the fifth embodiment, since the first portion 91 and the second portion 92 are formed on the base surface 90, a large radius of curvature R ₁ can be achieved even when the light emitting elements are arranged at a narrow pitch. Therefore, it is possible to make the radiation angle of the light emitted from the light emitting element a narrow radiation angle of 2 to 3 degrees or less, or as narrow as possible, and it is possible to provide a light emitting element having a narrow FFP, and to increase the light output and improve the efficiency of the light emitting element. Moreover, since the height (thickness) of the first portion 91 can be made low (thin), when the light emitting element array is connected and bonded to an external circuit or the like using bumps, it is difficult for cavities (voids) to occur in the bumps, and it is possible to improve the thermal conductivity. It goes without saying that the above description can also be applied to the light emitting elements of the first to fourth embodiments and the sixth to eleventh embodiments described later.

The manufacturing method of the light-emitting element of Example 5 is described below.

First, the same steps as [Step-100] to [Step-150] in Example 1 are performed. After that, a first sacrificial layer 81 is formed on a first portion 91 of the base surface 90 (specifically, the first surface 21a of the first compound semiconductor layer 21) on which the first light reflection layer 41 is to be formed, and then the surface of the first sacrificial layer is made convex. Specifically, a first resist material layer is formed on the first surface 21a of the first compound semiconductor layer 21, and the first resist material layer is patterned so as to leave the first resist material layer on the first portion 91, thereby obtaining the first sacrificial layer 81 shown in FIG. 35A. Then, the first sacrificial layer 81 is subjected to ashing treatment (plasma irradiation treatment) to alter the surface of the first sacrificial layer 81', and when the second sacrificial layer 82 is formed in the next step, damage, deformation, etc., are prevented from occurring in the first sacrificial layer 81'.

Next, a second sacrificial layer 82 is formed on the second portion 92 of the base surface 90 exposed between the first sacrificial layer 81' and the first sacrificial layer 81' and on the first sacrificial layer 81' to make the surface of the second sacrificial layer 82 uneven (see FIG. 36A). Specifically, the second sacrificial layer 82 is formed of a second resist material layer having an appropriate thickness on the entire surface. In the example shown in FIG. 11, the average thickness of the second sacrificial layer 82 is 2 μm, and in the example shown in FIG. 12, the average thickness of the second sacrificial layer 82 is 5 μm.

Alternatively, after forming a first sacrificial layer 81 on the first surface 21a of the first compound semiconductor layer 21, the surface of the first sacrificial layer 81 is made convex (see Figures 35A and 35B), and then the first sacrificial layer 81' is etched back, and the first compound semiconductor layer 21 is further etched back from the first surface 21a toward the inside to form a convex portion 91' when the second surface 21b of the first compound semiconductor layer 21 is used as a reference. In this way, the structure shown in Figure 37A can be obtained. Then, a second sacrificial layer 82 is formed on the entire surface (see Figure 37B).

The material constituting the first sacrificial layer 81 and the second sacrificial layer 82 is not limited to a resist material, and may be an oxide material (e.g., SiO ₂ , SiN, TiO ₂ , etc.), a semiconductor material (e.g., Si, GaN, InP, GaAs, etc.), a metal material (e.g., Ni, Au, Pt, Sn, Ga, In, Al, etc.), or any other material suitable for the first compound semiconductor layer 21. In addition, by using a resist material having a suitable viscosity as the resist material constituting the first sacrificial layer 81 and the second sacrificial layer 82, and by appropriately setting and selecting the thickness of the first sacrificial layer 81, the thickness of the second sacrificial layer 82, the diameter of the first sacrificial layer 81', etc., the value of the radius of curvature of the base surface 90 and the shape of the unevenness of the base surface 90 (e.g., the diameter D ₁ and the height H ₁ ) can be set to a desired value and shape.

Thereafter, the second sacrificial layer 82 and the first sacrificial layer 81' are etched back, and further etched back from the base surface 90 toward the inside (i.e., from the first surface 21a of the first compound semiconductor layer 21 toward the inside of the first compound semiconductor layer 21), thereby forming a convex portion 91A on the first portion 91 of the base surface 90 and at least a concave portion (in the fifth embodiment, a concave portion 92A) on the second portion 92 of the base surface 90, when the second surface 21b of the first compound semiconductor layer 21 is taken as a reference. In this way, the structure shown in FIG. 36B or FIG. 37C can be obtained. If it is necessary to further increase the radius of curvature R ₁ of the first portion 91 of the base surface 90, this process can be repeated. The etch back can be performed based on a dry etching method such as an RIE method, or based on a wet etching method using hydrochloric acid, nitric acid, hydrofluoric acid, phosphoric acid, a mixture thereof, or the like.

Next, the first light reflecting layer 41 is formed on the first portion 91 of the base surface 90. Specifically, after forming the first light reflecting layer 41 on the entire surface of the base surface 90 based on a film forming method such as a sputtering method or a vacuum deposition method (see FIG. 36C), the first light reflecting layer 41 is patterned to obtain the first light reflecting layer 41 on the first portion 91 of the base surface 90 (see FIG. 38A). Then, the first electrode 31 common to each light emitting element is formed on the second portion 92 of the base surface 90 (see FIG. 38B). In this way, the light emitting element array or light emitting element 10D of the fifth embodiment can be obtained. If the first electrode 31 is made to protrude from the first light reflecting layer 41, the first light reflecting layer 41 can be protected. Then, it is sufficient to electrically connect it to an external electrode or circuit (a circuit that drives the light emitting element). Specifically, the first compound semiconductor layer 21 may be connected to an external circuit or the like via the first electrode 31 and a first pad electrode (not shown), and the second compound semiconductor layer 22 may be connected to an external circuit or the like via the second electrode 32 and a second pad electrode. Next, the light-emitting device of Example 5 is completed by packaging or sealing.

Example 6 is a modification of Example 5 and relates to a light-emitting element of the B configuration. A schematic partial end view of the light-emitting element 10E of Example 6 is shown in FIG. 13, and a schematic partial end view of a light-emitting element array including a plurality of light-emitting elements 10E of Example 6 is shown in FIG. 14. In addition, schematic plan views of the arrangement of the first and second parts of the base surface in the light-emitting element array of Example 6 are shown in FIGS. 15 and 17, and schematic plan views of the arrangement of the first light reflecting layer and the first electrode in the light-emitting element array of Example 6 are shown in FIGS. 16 and 18. Furthermore, schematic partial end views of the first compound semiconductor layer, etc. for explaining the manufacturing method of the light-emitting element array of Example 6 are shown in FIGS. 39A, 39B, 40A, 40B, 41A, and 41B.

In the light-emitting device 10E of Example 6, when the second surface 21b of the first compound semiconductor layer 21 is used as a reference, the second portion 92 of the base surface 90 occupying the peripheral region 99 has a downwardly convex shape and an upwardly convex shape extending from the downwardly convex shape toward the center of the peripheral region 99. When the distance from the second surface 21b of the first compound semiconductor layer 21 to the center _91c of the first portion 91 of the base surface 90 is defined as LL ₁ and the distance from the second surface 21b of the first compound semiconductor layer 21 to the center _92c of the second portion 92 of the base surface 90 is defined as LL ₂ ,
_LL2 > _LL1
In addition, when the radius of curvature of the central portion 91 _c of the first portion 91 of the base surface 90 (i.e., the radius of curvature of the first light reflecting layer 41) is R ₁ , and the radius of curvature of the central portion 92 _c of the second portion 92 of the base surface 90 is R ₂ ,
_R1 > _R2
The value of _LL2 / _LL1 is not limited to the following:
1<LL ₂ /LL ₁ ≦100
Examples of the value of R ₁ /R ₂ include, but are not limited to,
1<R ₁ /R ₂ ≦100
Specifically, for example,
_LL2 / _LL1 =1.05
_R1 / _R2 =10
It is.

In the light emitting device 10E of Example 6, the center _91c of the first portion 91 of the base surface 90 is located on the apex (intersection) of a square lattice (see FIG. 15), and in this case, the center _92c of the second portion 92 of the base surface 90 (shown as a circle in FIG. 15) is located on the apex (intersection) of the square lattice. Alternatively, the center _91c of the first portion 91 of the base surface 90 is located on the apex (intersection) of an equilateral triangular lattice (see FIG. 17), and in this case, the center _92c of the second portion 92 of the base surface 90 (shown as a circle in FIG. 17) is located on the apex (intersection) of the equilateral triangular lattice. In addition, the second portion 92 of the base surface 90 occupying the peripheral region 99 has a downwardly convex shape toward the center of the peripheral region 99, and this region is indicated by reference number _92b in FIGS. 15 and 17.

In the light-emitting element 10E of Example 6, the shape of [the first portion 91/second portion 92 from the periphery to the center] corresponds to case (A) among cases (A) to (C) in the light-emitting element of the above-mentioned B configuration, specifically case (A).

In the light-emitting element 10E of Example 6, a bump 35 is arranged on the second surface side of the second compound semiconductor layer 22 facing the convex-shaped portion in the second portion 92 of the base surface 90.

As shown in FIG. 13, the second electrode 32 is common to the light emitting elements 10E constituting the light emitting element array, or as shown in FIG. 14, it is formed individually and is connected to an external circuit or the like via a second pad electrode 33 and a bump 35. The first electrode 31 is common to the light emitting elements 10E constituting the light emitting element array, and is connected to an external circuit or the like via a first pad electrode (not shown). The bump 35 is formed on a portion of the second surface side of the second compound semiconductor layer 22 facing the convex portion _92c in the second portion 92 of the base surface 90. In the light emitting element 10E shown in FIG. 13 and FIG. 14, light may be emitted to the outside via the first light reflecting layer 41, or light may be emitted to the outside via the second light reflecting layer 42. Examples of the shape of the bump 35 include a cylindrical shape, an annular shape, and a hemispherical shape.

The radius of curvature _R2 of the central portion _92c of the second portion 92 of the base surface 90 is desirably 1×10 ⁻⁶ m or more, preferably 3×10 ⁻⁶ m or more, and more preferably 5×10 ⁻⁶ m or more. Specifically,
Radius of curvature R ₂ =3 μm
It is.

In the light-emitting element array of Example 6 shown in Figures 15 and 16, as well as Figures 17 and 18, the parameters of the light-emitting element 10E are as shown in Table 11 below. The specifications of the light-emitting element 10E of Example 6 shown in Figures 15 and 16, as well as Figures 17 and 18 are shown in Tables 12 and 13 below. Here, when the distance from the second surface _21b of the first compound semiconductor layer 21 to the central portion _91c of the first portion 91 of the base surface 90 is defined as _LL1 , and the distance from the second surface 21b of the first compound semiconductor layer 21 to the deepest recessed portion _92b of the second portion 92 of the base surface 90 is defined as _LL2 '',
H ₁ = LL ₁ - LL ₂ ”
and the height _H2 of the center portion _92c of the second portion 92 is represented by
H ₂ = LL ₂ - LL ₂ ”
It is expressed as:

Table 11
See Fig. 15 and Fig. 16 See Fig. 17 and Fig. 18 Formation pitch 25 μm 25 μm
Radius of curvature R ₁ 150μm 150μm
Diameter D ₁ 20μm 20μm
Height _H1 2 μm 2 μm
Radius of curvature R ₂ 2μm 2μm
Height _H2 2.5 μm 2.5 μm

Table 12 See Figs. 15 and ₁₆ Second light reflecting layer 42 _SiO2 / _Ta2O5 (11.5 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 445 nm
Number of light emitting elements: 100 x 100

Table 13 See Figs. 17 and ₁₈ Second light reflecting layer 42 _SiO2 / _Ta2O5 (11.5 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 445 nm
Number of light emitting elements: 100 x 100

39A, 39B, 40A, 40B, 41A, and 41B are schematic partial end views of the first compound semiconductor layer and the like for explaining the manufacturing method of the light-emitting element array of Example 6. However, since the manufacturing method of the light-emitting element array of Example 6 can be substantially the same as the manufacturing method of the light-emitting element array of Example 5, detailed description will be omitted. Note that reference numeral 83 in FIG. 39A and reference numeral 83' in FIG. 39B and FIG. 40A indicate a portion of the first sacrificial layer for forming the central portion _92c of the second portion 92. Note that as the size (diameter) of the first sacrificial layer becomes smaller, the height of the first sacrificial layer after the heat treatment becomes higher.

In the light-emitting element array of Example 6 or Example 7 described later, when connecting/joining to an external circuit or the like using the bumps 35, it is necessary to apply a large load (for example, about 50 MPa) to the light-emitting element array during bonding. In the light-emitting element array of Example 6, even if such a large load is applied, the bumps 35 and the convex portion _92c in the second portion 92 of the base surface 90 are arranged in a straight line in the vertical direction, so that it is possible to reliably prevent damage to the light-emitting element array.

Example 7 is a modification of Examples 5 to 6, and relates to a light-emitting element of configuration C. Schematic partial end views of the light-emitting element array of Example 7 are shown in Figures 19 and 20, and a schematic plan view of the arrangement of the first and second parts of the base surface in the light-emitting element array of Example 7 is shown in Figure 21. In the example shown in Figure 19, the second electrode 32 is formed individually for each light-emitting element, and in the example shown in Figure 20, the second electrode 32 is formed in common for each light-emitting element.

In the light-emitting element 10F of Example 7, when the second surface 21b of the first compound semiconductor layer 21 is used as a reference, the second portion 92 of the base surface 90 occupying the peripheral region 99 has an annular convex shape 93 surrounding the first portion 91 of the base surface 90, and a downwardly convex shape 94A extending from the annular convex shape 93 toward the first portion 91 of the base surface 90. In the second portion 92 of the base surface 90 occupying the peripheral region 99, the region surrounded by the annular convex shape 93 is indicated by reference number 94B.

In the light-emitting element 10F of Example 7, when the distance from the second surface 21b of the first compound semiconductor layer 21 to the center portion _91c of the first portion 91 of the base surface 90 is defined as _LL1 , and the distance from the second surface 21b of the first compound semiconductor layer 21 to the apex of the annular convex shape 93 of the second portion 92 of the base surface 90 is defined as _LL2 ',
_LL2 '> _LL1
In addition, when the radius of curvature of the central portion 91 _c of the first portion 91 of the base surface 90 (i.e., the radius of curvature of the first light reflecting layer 41) is R ₁ , and the radius of curvature of the apex of the annular convex shape 93 of the second portion 92 of the base surface 90 is R ₂ ',
R ₁ >R ₂ '
The value of _LL2 '/ _LL1 is not limited to the following.
1< _LL2 '/ _LL1 ≦100
Specifically, for example,
LL ₂ '/LL ₁ = 1.1
In addition, the value of R ₁ /R ₂ ' is not limited, but may be:
1<R ₁ /R ₂ '≦100
Specifically, for example,
_R1 / _R2 '=50
It is.

In the light-emitting element 10F of Example 7, the shape of [the first portion 91/second portion 92 from the periphery to the center] corresponds to case (A) among cases (A) to (F) in the light-emitting element of the above-mentioned C configuration, specifically case (A).

In the light emitting device 10F of Example 7, a bump 35 is disposed on a portion of the second compound semiconductor layer 22 on the second surface side facing the portion of the annular convex shape 93 in the second portion 92 of the base surface 90. The bump 35 is preferably shaped like a ring facing the annular convex shape 93. Examples of the shape of the bump 35 include a cylindrical shape, an annular shape, and a hemispherical shape. The bump 35 is formed on a portion of the second compound semiconductor layer 22 on the second surface side facing the convex portion _92c in the second portion 92 of the base surface 90.

As shown in FIG. 19, the second electrode 32 is formed individually in the light-emitting element 10F constituting the light-emitting element array, and is connected to an external circuit, etc., via a bump 35. The first electrode 31 is common to the light-emitting element 10F constituting the light-emitting element array, and is connected to an external circuit, etc., via a first pad electrode (not shown). Alternatively, as shown in FIG. 20, the second electrode 32 is common to the light-emitting element 10F constituting the light-emitting element array, and is connected to an external circuit, etc., via a bump 35. The first electrode 31 is common to the light-emitting element 10F constituting the light-emitting element array, and is connected to an external circuit, etc., via a first pad electrode (not shown). In the light-emitting element 10F shown in FIG. 19 and FIG. 20, light may be emitted to the outside through the first light reflecting layer 41, or light may be emitted to the outside through the second light reflecting layer 42.

The radius of curvature R ₂ ' of the annular convex shape 93 of the second portion 92 of the base surface 90 is desirably 1×10 ⁻⁶ m or more, preferably 3×10 ⁻⁶ m or more, and more preferably 5×10 ⁻⁶ m or more. Specifically,
Radius of curvature R ₂ '=5μm
It is.

In the light-emitting element array of Example 7 shown in FIG. 21, the parameters of the light-emitting element 10F are as shown in Table 14 below. The specifications of the light-emitting element 10F of Example 7 shown in FIG. 21 are shown in Table 15 below. Here, the height H ₁ of the first portion 91 is expressed as follows, when the distance from the second surface 21 b of the first compound semiconductor layer 21 to the center portion 91 _c of the first portion 91 on the base surface 90 is defined as LL ₁ , and the distance from the second surface 21 b of the first compound semiconductor layer 21 to the deepest recessed portion 92 _b of the second portion 92 on the base surface 90 is defined as LL ₂ ″:
H ₁ = LL ₁ - LL ₂ ”
The height _H2 of the annular convex shape 93 of the second portion 92 is expressed as follows:
H ₂ = LL ₂ - LL ₂ ”
In addition, the diameter _D2 indicates the diameter of the annular convex shape 93.

<Table 14>
See FIG. 21. Formation pitch: 25 μm
Radius of curvature R ₁ 150μm
Diameter _{D1 15} μm
Height H1 ₂ μm
Radius of curvature R2 ₃ μm
Diameter D ₂ 19μm (inner diameter 18μm/outer diameter 20μm)
Height H2 ₃ μm

Table 15 See FIG. 21 Second light reflecting layer 42 SiO ₂ /Ta ₂ O ₅ (7 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 20μm
Oscillation wavelength (emission wavelength) λ ₀ 405 nm
Number of light emitting elements: 1000 x 1000

The manufacturing method for the light-emitting element array of Example 7 can be substantially the same as the manufacturing method for the light-emitting element array of Example 5 or Example 6, so a detailed explanation will be omitted.

Example 8 is a modification of Example 5. Figures 22A and 22B are schematic plan views showing the arrangement of the first and second parts of the base surface in the light-emitting element array of Example 8. In the example shown in Figure 22A, the light-emitting element array has, for example, the light-emitting elements of Example 5 arranged in a row. The schematic partial end view along the arrow A-A in Figure 22A is similar to that shown in Figure 9. In the example shown in Figure 22B, the light-emitting element array has, for example, light-emitting elements whose planar shape is longer and thinner than the light-emitting elements of Example 5 arranged in a row. The schematic partial end view along the arrow A-A in Figure 22B is similar to that shown in Figure 9. In the light-emitting element array of Example 8 shown in Figure 22A, the parameters of the light-emitting elements are as shown in Table 16 below, and the specifications of the light-emitting elements are shown in Table 17 below. In addition, in the light-emitting element array of Example 8 shown in Figure 22B, the parameters of the light-emitting elements are as shown in Table 18 below, and the specifications of the light-emitting elements are shown in Table 19 below. The shape of the base surface shown in FIG. 22B is a part of a cylindrical shape or a part of a semi-cylindrical shape.

<Table 16>
See FIG. 22A Formation pitch: 25 μm
Radius of curvature R ₁ 100μm
Diameter _D1 20 μm
Height H1 ₂ μm

Table 17 See FIG. 22A Second light reflecting layer 42 SiO ₂ /Ta ₂ O ₅ (11.5 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 445 nm
Number of light emitting elements: 1000 x 1

<Table 18>
See FIG. 22B Formation pitch: 25 μm (pitch along arrow B in FIG. 22B)
Radius of curvature R ₁ 100 μm (radius of curvature in the direction of arrow B in FIG. 22B)
Size of the first part: length 400 μm × width 20 μm
Height H1 ₂ μm

Table 19 See FIG. 22B Second light reflecting layer 42 SiO ₂ /Ta ₂ O ₅ (11.5 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 445 nm
Number of light emitting elements: 512 x 1

Example 9 is a modification of Examples 3, 4, and 5 to 8. The configuration and structure of the light-emitting element of Example 9 can be substantially the same as the configuration and structure of the light-emitting element of Examples 3, 4, and 5 to 8, so a detailed description will be omitted.

In Example 9, first, the second surface 11b of the light-emitting element manufacturing substrate 11 is provided with an uneven surface 96 for forming a base surface 90 (see FIG. 42A). Then, the first light reflecting layer 41 made of a multilayer film is formed on the second surface 11b of the light-emitting element manufacturing substrate 11 (see FIG. 42B), and then a planarization film 97 is formed on the first light reflecting layer 41 and the second surface 11b, and a planarization process is performed on the planarization film 97 (see FIG. 42C).

Next, a laminated structure 20 is formed based on lateral growth using a method of epitaxial growth in the lateral direction, such as the ELO method, on the planarization film 97 of the light-emitting element manufacturing substrate 11 including the first light reflecting layer 41. Thereafter, the light-emitting element manufacturing substrate 11 is removed, and the first electrode 31 is formed on the exposed planarization film 97. Alternatively, the first electrode 31 is formed on the first surface 11a of the light-emitting element manufacturing substrate 11 without removing the light-emitting element manufacturing substrate 11.

Example 10 is a modification of Examples 1 to 9. In the light-emitting element of Example 10, partition walls 24, 25 are formed to surround the first light reflecting layer 41 and extend in the stacking direction of the laminated structure 20. By forming the partition walls 24, 25, the occurrence of optical crosstalk can be prevented.

A partition extending in the stacking direction of the laminated structure 20 is formed so as to surround the first light reflecting layer 41. The orthogonal projection image of the first light reflecting layer 41 may be included in the orthogonal projection image (hereinafter, sometimes referred to as the "partition side") of the side of the partition facing the first light reflecting layer 41, or the orthogonal projection image of the partition side may be included in the orthogonal projection image of the part of the first light reflecting layer 41 that does not contribute to light reflection (the non-effective area of the first light reflecting layer 41). Alternatively, the base surface 90 on which the first light reflecting layer 41 is formed may be included in the orthogonal projection image of the partition side. The partition side may be a continuous surface or a discontinuous surface with a portion cut out. The "orthogonal projection image" refers to the orthogonal projection image obtained when orthogonally projected onto the laminated structure 20.

The partition 24 may extend from the first surface side of the first compound semiconductor layer 21 through the first compound semiconductor layer 21 to the middle of the thickness direction of the first compound semiconductor layer 21. That is, the upper end of the partition 24 may be located at the middle of the thickness direction of the first compound semiconductor layer 21. The lower end of the partition 24 may be exposed to the first surface of the light-emitting element, or may not be exposed to the first surface of the light-emitting element. Here, the "first surface of the light-emitting element" refers to the exposed surface of the light-emitting element on the side where the first light reflecting layer 41 is provided, and the "second surface of the light-emitting element" refers to the exposed surface of the light-emitting element on the side where the second light reflecting layer is provided. In the light-emitting element array of the present disclosure, the relationship between L ₀ , L ₁ , and L ₃ is as follows:
The following formula (1) is satisfied, or preferably the following formula (1') is satisfied:
The following formula (2) is satisfied, or preferably the following formula (2') is satisfied:
The following formulas (1) and (2) are satisfied, or
It is desirable to satisfy the following formula (1') and formula (2').
0.01×L ₀ ≦L ₀ -L ₁ (1)
0.05×L ₀ ≦L ₀ -L ₁ (1')
0.01×L ₃ ≦L ₁ (2)
0.05×L ₃ ≦L ₁ (2')
Where:
L ₀ : distance from an end of the opposing surface of the first light reflecting layer 41 opposing the first surface of the first compound semiconductor layer 21 to the active layer 23 L ₁ : distance from the active layer 23 to an end of the partition wall 24 (the upper end of the partition wall 24, the end facing the active layer 23) extending through the first compound semiconductor layer 21 to the middle of the thickness direction of the first compound semiconductor layer 21 L ₃ : distance from the axis of the first light reflecting layer 41 constituting the light emitting element to an orthogonal projection image of the partition wall 24 onto the stacked structure 20 (more specifically, an orthogonal projection image of the upper end of the partition wall 24). Note that although the upper limit of (L ₀ -L ₁ ) is less than L ₀ , when no short circuit occurs between the active layer 23 and the first electrode due to the partition wall 24, the upper limit of (L ₀ -L ₁ ) may be L ₀ or more.

Alternatively, the partition 25 may extend from the second surface side of the second compound semiconductor layer 22 into the second compound semiconductor layer 22 and into the active layer 23, and further extend into the first compound semiconductor layer 21 to the middle of the thickness direction of the first compound semiconductor layer 21. That is, the lower end of the partition 25 may be located halfway through the thickness direction of the first compound semiconductor layer 21. The upper end of the partition 25 may be exposed to the second surface of the light-emitting element in some cases, or may not be exposed to the second surface of the light-emitting element in other cases. In such a case, the relationship between L ₀ , L _{2 ,} and L ₃ ' is as follows:
The following formula (3), preferably formula (3′), is satisfied, or
The following formula (4), preferably formula (4'), is satisfied, or
The following formulas (3) and (4) are satisfied, or
It is desirable to satisfy the following formula (3') and formula (4').
0.01×L ₀ ≦L ₂ (3)
0.05×L ₀ ≦L ₂ (3')
0.01×L ₃ '≦L ₂ (4)
0.05×L ₃ '≦L ₂ (4')
Where:
L ₀ : Distance from the end of the facing surface of the first light reflecting layer 41 facing the first surface of the first compound semiconductor layer 21 to the active layer 23 L ₂ : Distance from the active layer 23 to the end of the partition 25 (the lower end of the partition 25, the end facing the first electrode) extending in the first compound semiconductor layer 21 to the middle of the thickness direction of the first compound semiconductor layer 21 L ₃ ': Distance from the axis of the first light reflecting layer 41 constituting the light emitting element to the orthogonal projection image of the partition 25 on the stacked structure 20 (more specifically, the orthogonal projection image of the lower end of the partition 25). Note that the upper limit of L ₂ is less than L ₀ , but if no short circuit occurs between the active layer 23 and the first electrode due to the partition 25, the upper limit of L ₂ may be L ₀ .

The partitions 24 and 25 may be made of a material that does not transmit the light generated in the active layer 23, thereby preventing the generation of stray light and optical crosstalk. Specifically, such materials include materials capable of blocking light, such as titanium (Ti), chromium (Cr), tungsten (W), tantalum (Ta), aluminum (Al), and MoSi _2, and may be formed by, for example, an electron beam deposition method, a hot filament deposition method, a deposition method including a vacuum deposition method, a sputtering method, a CVD method, an ion plating method, or the like. Alternatively, a black resin film having an optical density of 1 or more containing a black colorant (specifically, for example, a black polyimide resin, an epoxy resin, or a silicone resin) may be used.

Alternatively, the partitions 24 and 25 can be made of a material that reflects the light generated in the active layer 23, which can prevent the generation of stray light and optical crosstalk, and can efficiently return stray light to the light-emitting element itself, thereby contributing to improving the light-emitting efficiency of the light-emitting element. Specifically, the partitions 24 and 25 are made of thin-film filters that utilize the interference of thin films. The thin-film filter has a different stacking direction (alternate arrangement direction) from, for example, the light-reflecting layers 41 and 42, but has the same configuration and structure. Specifically, a recess is formed in a part of the laminated structure 20, and the inside of this recess is filled sequentially with the same material as the light-reflecting layers 41 and 42 based on, for example, a sputtering method, so that when the partitions 24 and 25 are cut in a virtual plane (XZ plane) perpendicular to the stacking direction of the laminated structure 20, a thin-film filter in which dielectric layers are alternately arranged can be obtained. Alternatively, examples of such materials include metal materials, alloy materials, and metal oxide materials. More specifically, examples of such materials include copper (Cu) and its alloys, gold (Au) and its alloys, tin (Sn) and its alloys, silver (Ag) and silver alloys (e.g., Ag-Pd-Cu, Ag-Sm-Cu), platinum (Pt) and its alloys, palladium (Pd) and its alloys, titanium (Ti) and its alloys, aluminum (Al) and aluminum alloys (e.g., Al-Nd and Al-Cu), an Al/Ti laminated structure, an Al-Cu/Ti laminated structure, chromium (Cr) and its alloys, and ITO. For example, the metal layer can be formed by deposition methods including electron beam deposition, hot filament deposition, and vacuum deposition, sputtering, CVD, and ion plating; plating methods (electroplating and electroless plating); lift-off methods; laser ablation methods; sol-gel methods; plating methods, and the like.

Alternatively, when the thermal conductivity of the material constituting the first compound semiconductor layer 21 is TC ₁ and the thermal conductivity of the material constituting the partition walls 24 and 25 is TC ₀ ,
1×10 ^-1 ≦TC ₁ /TC ₀ ≦1×10 ²
The partition walls 24 and 25 can be formed in a form that satisfies the above. Specific examples of materials constituting such partition walls 24 and 25 include metals such as silver (Ag), copper (Cu), gold (Au), tin (Sn), aluminum (Al), ruthenium (Ru), rhodium (Rh), platinum (Pt), or alloys or mixtures of these metals, ITO, and the like. For example, the partition walls 24 and 25 can be formed by deposition methods including electron beam deposition, hot filament deposition, and vacuum deposition, sputtering, CVD, and ion plating; plating methods (electroplating and electroless plating); lift-off methods; laser ablation methods; sol-gel methods; plating methods, and the like. By forming the partition walls 24 and 25 from materials having high thermal conductivity in this way, heat generated in the laminated structure 20 can be exhausted (dissipated) to the outside through the partition walls 24 and 25. In this case, a partition extension portion may be formed on the outer surface (first surface or second surface) of the light-emitting element so that heat generated in the laminated structure 20 can be exhausted (dissipated) to the outside via the partitions 24, 25 and the partition extension portion, or the partitions 24, 25 may be connected to the first electrode 31 or the second electrode 32 or the pad electrode so that heat generated in the laminated structure 20 can be exhausted (dissipated) to the outside via the partitions 24, 25 and the first electrode 31 or the second electrode 32 or the pad electrode.

Alternatively, when the linear expansion coefficient of the material constituting the first compound semiconductor layer 21 is CTE ₁ and the linear expansion coefficient of the material constituting the partition walls 24 and 25 is CTE ₀ ,
｜CTE ₀ -CTE ₁ ｜≦1×10 ^-4 /K
The partition walls 24 and 25 can be formed to satisfy the above requirements. Specific examples of materials for forming the partition walls 24 and 25 include polyimide resins, silicone resins, epoxy resins, carbon materials, SOG, polycrystalline GaN, and single-crystalline GaN. By specifying the linear expansion coefficient in this way, the thermal expansion coefficient of the entire light-emitting element can be optimized, and the thermal expansion of the light-emitting element can be controlled (suppressed). Specifically, for example, the net thermal expansion coefficient of the laminated structure 20 can be increased, and by matching it to the thermal expansion coefficient of the substrate material on which the light-emitting element is mounted, it is possible to prevent damage to the light-emitting element and suppress a decrease in the reliability of the light-emitting element due to the generation of stress. The partition walls 24 and 25 made of polyimide resin can be formed, for example, based on a spin-coat method and a curing method.

Alternatively, if the partitions 24 and 25 are made of an insulating material, the occurrence of electrical crosstalk can be suppressed. In other words, it is possible to prevent unnecessary current from flowing between adjacent light-emitting elements.

Alternatively, the partition 25 may be made of a solder material, and a part of the partition 25 may be exposed on the outer surface of the light-emitting element. The part of the partition 25 exposed on the outer surface of the light-emitting element may form a kind of bump. As a material for forming such a partition wall 25, specifically, Au-Sn eutectic solder, so-called low melting point metal (alloy) material, solder material, and brazing material can be used, for example, In (indium: melting point 157°C); indium-gold based low melting point alloy; tin (Sn) based high temperature solder such as Sn ₈₀ Ag ₂₀ (melting point 220-370°C) and Sn ₉₅ Cu ₅ (melting point 227-370°C ₎ ; lead (Pb) based high temperature solder such as Pb _97.5 Ag _2.5 (melting point 304°C), Pb _94.5 Ag _5.5 (melting point 304-365°C), Pb _97.5 Ag _1.5 Sn _1.0 (melting point 309°C) _; Examples of suitable solders include zinc (Zn)-based high-temperature solders such as _Sn5Pb95 (melting point 300-314°C) _{and Sn2Pb98} ( _melting point 316-322°C); and brazing filler _metals such as _Au88Ga12 (melting point 381°C) (all of the above subscripts indicate atomic %).

Furthermore, the side of the partition 25 can be narrowed along the direction from the first surface side of the first compound semiconductor layer 21 toward the second surface side of the second compound semiconductor layer 22. That is, the shape of the side of the partition 25 when the light-emitting element is cut in a virtual plane (XZ plane) including the stacking direction of the stacked structure 20 can be a trapezoid (an isosceles trapezoid with the second compound semiconductor layer side being the short side and the first compound semiconductor layer side being the long side). This allows stray light to be returned to the light-emitting element itself more efficiently.

Examples of the shape of the side of the partitions 24 and 25 when the light-emitting element is cut in a virtual plane (XZ plane) including the stacking direction of the laminated structure 20 include a line segment, an arc, a part of a parabola, and a part of an arbitrary curve. Examples of the shape of the side of the partitions 24 and 25 when the light-emitting element is cut in a virtual plane (XY plane) perpendicular to the stacking direction of the laminated structure 20 include a circle, an ellipse, an oval, a rectangle including a square or a rectangle, and a regular polygon (including a rounded regular polygon). Specific examples of the planar shape of the first light-reflecting layer 41 and the second light-reflecting layer include a circle, an ellipse, an oval, a rectangle, and a regular polygon (equilateral triangle, square, regular hexagon, etc.). It is desirable that the planar shape of the first light-reflecting layer 41 and the second light-reflecting layer and the shape of the side of the partitions 24 and 25 when the light-emitting element is cut in a virtual plane (XY plane) perpendicular to the stacking direction of the laminated structure 20 are similar or approximate.

When the light-emitting elements are arranged in an array, the partitions 24, 25 are provided so as to surround the first light-reflecting layer 41 constituting each light-emitting element, but the area outside the partition side surface may be occupied by the partitions 24, 25 (i.e., the space between the light-emitting elements may be occupied by the material constituting the partitions 24, 25), or may be occupied by a material other than the material constituting the partitions 24, 25 (e.g., the laminated structure 20). In the latter case, the partitions 24, 25 are formed, for example, in the shape of a continuous groove or a discontinuous groove.

Below, the light-emitting element 10G of Example 10 is described in detail.

Schematic partial cross-sectional views of the light-emitting element array in Example 10 are shown in Figures 23 and 25, and schematic partial cross-sectional views of the light-emitting element 10G are shown in Figures 24 and 26. Here, Figures 23 and 24 show an example in which the partition 24 is made of a material that is not conductive, and Figures 3 and 4 show an example in which the partition 24 is made of a material that is conductive or an example in which the partition 24 is made of a material that is not conductive. The partition 24 is formed to extend in the stacking direction of the laminated structure 20 so as to surround the first light reflecting layer 41.

As shown in the figure, the orthogonal projection image of the first light reflecting layer 41 may be included in the orthogonal projection image of the side surface 24' of the partition 24 facing the first light reflecting layer 41, or, although not shown, the orthogonal projection image of the partition side surface 24' may be included in the orthogonal projection image of a portion of the first light reflecting layer 41 that does not contribute to light reflection (a non-effective area of the first light reflecting layer 41). In addition, the side surface 24' of the partition 24 may be a continuous surface or a discontinuous surface with a portion cut out. The same can be applied to the partition 25 of Example 11 described later.

In the light-emitting element 10G of Example 10, the partition wall 24 extends from the first surface side of the first compound semiconductor layer 21 through the first compound semiconductor layer 21 to the middle of the thickness direction of the first compound semiconductor layer 21. That is, the upper end portion (the end portion facing the active layer 23) 24b of the partition wall 24 is located halfway through the thickness direction of the first compound semiconductor layer 21. In the light-emitting element array of Example 1, the relationship between L0 _{, L1,} and _L3 satisfies the relationship described above. Specifically, it is as shown in Table 23 described later.

The partition 24 is made of a material that does not transmit the light generated in the active layer 23. Alternatively, when the thermal conductivity of the material constituting the first compound semiconductor layer 21 is TC ₁ and the thermal conductivity of the material constituting the partition 24 is TC ₀ ,
1×10 ^-1 ≦TC ₁ /TC ₀ ≦1×10 ²
Specifically, the material constituting the first compound semiconductor layer 21 is made of GaN, and the partition wall 24 is made of copper (Cu).
TC ₀ : 50 Watts/(m·K) to 100 Watts/(m·K)
_TC1 : 400 watts/(mK)
For example, when the partition wall 24 made of a copper layer is formed by a plating method, a base layer made of an Au layer or the like having a thickness of about 0.1 μm is formed in advance as a seed layer by a sputtering method or the like, and a copper layer is formed thereon by a plating method. By forming the partition wall 24 from a material having high thermal conductivity in this way, heat generated in the laminated structure 20 can be effectively exhausted (dissipated) to the outside through the partition wall 24.

Alternatively, the partition 24 is made of a material that reflects light generated in the active layer 23, such as silver (Ag).

Alternatively, when the linear expansion coefficient of the material (GaN) constituting the first compound semiconductor layer 21 is CTE ₁ and the linear expansion coefficient of the material (polyimide resin) constituting the partition wall 24 is CTE ₀ ,
｜CTE ₀ -CTE ₁ ｜≦1×10 ^-4 /K
Specifically,
CTE ₀ :5.5× ^10-6 /K
CTE ₁ : 25×10 ^-6 /K
By combining these materials, the net thermal expansion coefficient of the light emitting element 10G can be increased and can be matched with the thermal expansion coefficient of the substrate material on which the light emitting element 10G is mounted, and therefore, damage to the light emitting element 10G and deterioration in reliability due to stress generation in the light emitting element 10G can be suppressed.

When the light-emitting element 10G is cut in a virtual plane (for example, the XZ plane in the illustrated example) including the stacking direction of the laminated structure 20, the shape of the side 24' of the partition 24 is a line segment. When the light-emitting element 10G is cut in a virtual plane (XY plane) perpendicular to the stacking direction of the laminated structure 20, the shape of the side 24' of the partition 24 is a circle. Furthermore, the partition 24 is provided so as to surround the first light reflecting layer 41 constituting each light-emitting element 10G, and the area outside the side 24' of the partition 24 is occupied by the partition 24. In other words, the material constituting the partition 24 occupies the space between the light-emitting elements 10G and the light-emitting elements 10G.

As shown in Figures 23 and 24, when the partition 24 is made of a non-conductive material, a first electrode 31 is provided on the first surface 21a of the first compound semiconductor layer 21.

25 and 26, when the partition 24 is made of a material having electrical conductivity, or when the partition 24 is made of a material having no electrical conductivity, the first electrode 31 may be provided on the exposed surface (lower end surface 24a) of the partition 24. Specifically, the lower end (end facing the first electrode 31) 24a of the partition 24 is in contact with the first electrode 31 formed on the first surface 10a (first surface 21a of the first compound semiconductor layer 21) of the light-emitting element 10G. The second surface 10b of the light-emitting element 10G is the exposed surface of the light-emitting element. When the partition 24 is made of a material having electrical conductivity, the partition 24 may also serve as the first electrode 31. By making the partition 24 from a material having high thermal conductivity in this way, the heat generated in the laminated structure 20 can be exhausted (dissipated) to the outside through the partition 24. Specifically, heat generated in the laminated structure 20 can be effectively discharged (dissipated) to the outside via the partition wall 24 and the first electrode 31 or the first pad electrode.

However, this is not limited thereto, and the space between the light-emitting elements 10G may be occupied by a material (e.g., the laminated structure 20) other than the material constituting the partition 24. That is, the partition 24 may be formed, for example, in the shape of a continuous groove, or may be formed in the shape of a discontinuous groove.

The first compound semiconductor layer 21 has a first conductivity type (specifically, n-type), and the second compound semiconductor layer 22 has a second conductivity type (specifically, p-type) different from the first conductivity type. In the light-emitting element 10G of Example 1, the first surface 21a of the first compound semiconductor layer 21 constitutes the base surface 90. The first light reflecting layer 41 is formed on the base surface 90. The base surface 90 has a convex shape facing away from the active layer 23.

23, 24, 25 and 26, the second electrode 32 is common to the light-emitting elements 10G constituting the light-emitting element array, and the second electrode 32 is connected to an external circuit or the like via a first pad electrode (not shown). The first electrode 31 is also common to the light-emitting elements 10G constituting the light-emitting element array, and is connected to an external circuit or the like via a first pad electrode (not shown). Then, light may be emitted to the outside via the first light reflecting layer 41, or light may be emitted to the outside via the second light reflecting layer 42.

In the light-emitting element array of Example 10, the parameters of the light-emitting element 10G are as shown in Table 20 below. The diameter of the first light reflecting layer 41 is indicated by _D1 , and the height of the base surface ₉₀ is indicated by _H1 (see FIG. 23). The specifications of the light-emitting element 10G of Example 10 having the same arrangement as shown in FIG. 11 and FIG. 12 are shown in Tables 21 and 22 below. Furthermore, the values of P0, _L0 , _L1, and _L3 are shown in Table 23, and the values of P0 _{, L0} , _L2, and _L3 ' in Example 11 described later are shown in Table 24.

Table 20
See Fig. 11 See Fig. 12 Formation pitch 25 μm 20 μm
Radius of curvature R ₁ 100μm 200μm
Diameter D ₁ 20μm 15μm
Height _H1 2 μm 2 μm

Table 21 See FIG. 11 Second light reflecting layer 42 SiO ₂ /Ta ₂ O ₅ (11.5 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 445 nm
Number of light emitting elements: 100 x 100

Table 22 See FIG. 12 Second light reflecting layer 42 SiO ₂ /SiN (9 pairs)
Second electrode 32 See Example 1 Second compound semiconductor layer 22 p-GaN
Active layer 23: InGaN (multiple quantum well structure)
First compound semiconductor layer 21 n-GaN
First light reflecting layer 41 _SiO2 / _Ta2O5 (14 _pairs )

Resonator length L _OR 25μm
Oscillation wavelength (emission wavelength) λ ₀ 488 nm
Number of light emitting elements: 1000 x 1000

Table 23 Example 10
_P0 : 40 μm
_L0 : 30 μm
_L1 : 28 μm
_L3 : 18 μm

Table 24 Example 11
_P0 : 20 μm
_L0 : 17 μm
_L2 : 12 μm
_L3 ': 9 μm

In the light-emitting element or light-emitting element array of Example 10, a partition wall 24 is formed extending in the stacking direction of the stacked structure 20 so as to surround the first light reflecting layer 41, so that the occurrence of optical crosstalk or the occurrence of thermal saturation can be prevented. As a result, a light-emitting element and a light-emitting element array having high light-emitting efficiency and high reliability can be provided.

Example 11 is a modification of Example 10. A schematic partial cross-sectional view of the light-emitting element array of Example 11 is shown in Figure 27, and a schematic partial cross-sectional view of the light-emitting element is shown in Figure 28.

In the light-emitting element 10H of Example 11, the partition wall 25A extends from the second surface side of the second compound semiconductor layer 22 into the second compound semiconductor layer 22 and into the active layer 23, and further extends into the first compound semiconductor layer 21 to the middle of the thickness direction of the first compound semiconductor layer 21. That is, the lower end 25a of the partition wall 25A is located halfway in the thickness direction of the first compound semiconductor layer 21. In the light-emitting element array of Example 11, the relationship between _L0 , _L2, and _L3 ' satisfies the above-mentioned relationship, as shown in Table 24 above. The upper end 25b of the partition wall 25B is exposed to the second surface 10b of the light-emitting element 10H.

29 is a schematic partial cross-sectional view of a modified example 1 of the light-emitting element 10H of Example 11, the upper end 25b of the partition 25B does not have to be exposed to the second surface 10b of the light-emitting element 10H. Specifically, the upper end 25b of the partition 25B is covered by the insulating layer (current confinement layer) 34 and the second electrode 32.

30 is a schematic partial cross-sectional view of Modification 2 of the light-emitting element 10H of Example 11, in which the side surface 25' of the partition wall 25C narrows in the direction from the first surface side of the first compound semiconductor layer 21 toward the second surface side of the second compound semiconductor layer 22. That is, when the light-emitting element 10H is cut in an imaginary plane (for example, the XZ plane in the illustrated example) including the stacking direction of the stacked structure 20, the shape of the side surface of the partition wall 25C is a trapezoid, specifically, an isosceles trapezoid with the short side on the second compound semiconductor layer side and the long side on the first compound semiconductor layer side.

These partitions 25A, 25B, and 25C can be made of materials similar to those of partition 24 described in Example 10.

31 is a schematic partial cross-sectional view of Modification 3 of the light-emitting element 10H of Example 11, in which the partition 25D is made of a solder material, specifically, for example, Au-Sn eutectic solder, and a portion 25D' of the partition 25D is formed on the outer surface (second surface 10b) of the light-emitting element 10H. Specifically, a type of bump is formed by the portion 25D' of the partition 25D exposed from the second surface 10b of the light-emitting element 10, and connection to an external circuit or the like can be made via the portion 25D' of the partition 25D.

Although the present disclosure has been described above based on preferred embodiments, the present disclosure is not limited to these embodiments. The configuration and structure of the light-emitting element described in the embodiments are illustrative and can be changed as appropriate, and the manufacturing method of the light-emitting element can also be changed as appropriate. In some cases, by appropriately selecting the bonding layer and the support substrate, a surface-emitting laser element that emits light from the second surface of the second compound semiconductor layer through the second light reflecting layer can be obtained. In some cases, a through hole leading to the first compound semiconductor layer can be formed in the region of the second compound semiconductor layer and the active layer that does not affect the light emission, and a first electrode insulated from the second compound semiconductor layer and the active layer can be formed in this through hole. The first light reflecting layer may extend to the second portion of the base surface. That is, the first light reflecting layer on the base surface may be composed of a so-called solid film. In this case, a through hole is formed in the first light reflecting layer that extends to the second portion of the base surface, and a first electrode connected to the first compound semiconductor layer may be formed in this through hole. In addition, the base surface 90 can be formed by providing a sacrificial layer based on the nanoimprint method.

A wavelength conversion material layer (color conversion material layer) may be provided in the region where the light of the light-emitting element is emitted. In this case, white light may be emitted through the wavelength conversion material layer (color conversion material layer). Specifically, when the light emitted in the active layer is emitted to the outside through the first light reflecting layer, the wavelength conversion material layer (color conversion material layer) may be formed on the light emission side of the first light reflecting layer, and when the light emitted in the active layer is emitted to the outside through the second light reflecting layer, the wavelength conversion material layer (color conversion material layer) may be formed on the light emission side of the second light reflecting layer.

When blue light is emitted from the light emitting layer, the following configuration can be adopted to make it possible to emit white light via the wavelength converting material layer.
[A] By using a wavelength converting material layer that converts the blue light emitted from the light emitting layer into yellow light, white light that is a mixture of blue and yellow light is obtained as the light emitted from the wavelength converting material layer.
[B] By using a wavelength converting material layer that converts the blue light emitted from the light emitting layer into orange light, white light that is a mixture of blue and orange is obtained as the light emitted from the wavelength converting material layer.
[C] By using a wavelength converting material layer that converts the blue light emitted from the light emitting layer into green light and a wavelength converting material layer that converts it into red light, white light that is a mixture of blue, green, and red is obtained as the light emitted from the wavelength converting material layer.

Alternatively, when ultraviolet light is emitted from the light emitting layer, the following configuration can be adopted to make it possible to emit white light via the wavelength converting material layer.
[D] By using a wavelength converting material layer that converts the ultraviolet light emitted from the light emitting layer into blue light and a wavelength converting material layer that converts it into yellow light, white light that is a mixture of blue and yellow is obtained as the light emitted from the wavelength converting material layer.
[E] By using a wavelength converting material layer that converts the ultraviolet light emitted from the light emitting layer into blue light and a wavelength converting material layer that converts it into orange light, white light that is a mixture of blue and orange is obtained as the light emitted from the wavelength converting material layer.
[F] By using a wavelength converting material layer that converts the ultraviolet light emitted from the light emitting layer into blue light, a wavelength converting material layer that converts it into green light, and a wavelength converting material layer that converts it into red light, white light that is a mixture of blue, green, and red is obtained as the light emitted from the wavelength converting material layer.

Here, examples of wavelength conversion materials that are excited by blue light and emit red light include red-emitting phosphor particles, more specifically, (ME:Eu)S [wherein "ME" means at least one type of atom selected from the group consisting of Ca, Sr, and Ba, and the same applies hereinafter], (M:Sm) _x (Si,Al) ₁₂ (O,N) ₁₆ [wherein "M" means at least one type of atom selected from the group consisting of Li, Mg, and Ca, and the same applies hereinafter], _ME2Si5N8 :Eu, (Ca: _{Eu)SiN2 ,} and (Ca _: Eu) _AlSiN3 . In addition, as wavelength conversion materials excited by blue light and emitting green light, specifically, green light-emitting phosphor _particles , more specifically, (ME:Eu) _Ga2S4 , (M:RE) _x (Si,Al) ₁₂ (O,N) ₁₆ [wherein "RE" means Tb and Yb], (M:Tb) _x (Si,Al) ₁₂ (O,N) ₁₆ , (M:Yb) _x (Si,Al) ₁₂ ( _O ,N) ₁₆ , and Si6 _{- ZAlZOZN8 -Z} :Eu can be mentioned. Furthermore, as wavelength conversion materials excited by blue light and emitting yellow light, specifically, yellow light-emitting phosphor particles, more specifically, YAG (yttrium aluminum garnet) phosphor particles can be mentioned. The wavelength conversion material may be one type, or two or more types may be mixed and used. Furthermore, by using a mixture of two or more types of wavelength converting materials, it is possible to configure so that light of a color other than yellow, green, and red is emitted from the wavelength converting material mixture. Specifically, for example, a configuration that emits cyan light may be used. In this case, green light-emitting phosphor particles (e.g., _LaPO4 :Ce, Tb, _BaMgAl10O17 :Eu, Mn, _Zn2SiO4 : _Mn , _MgAl11O19 :Ce, Tb, _Y2SiO5 : _Ce , _Tb , _MgAl11O19 :CE, Tb, _Mn ) and blue light-emitting phosphor particles ₍ e.g. _{, BaMgAl10O17} :Eu, _{BaMg2Al16O27 : Eu , Sr2P2O7 :} Eu, _Sr5 ( _PO4 ) _{3Cl :} Eu, ( _Sr ,Ca,Ba,Mg) _... For example, a mixture of CaWO ₄ and CaWO ₄ :Pb may be used.

Furthermore, examples of wavelength conversion materials that are excited by ultraviolet light and emit red light include red-emitting phosphor particles, more specifically, _Y2O3 :Eu, _YVO4 :Eu, _Y (P,V) _O4 :Eu, _{3.5MgO.0.5MgF2.Ge2} :Mn, CaSiO3: _Pb , _{Mn, Mg6AsO11 :} Mn, (Sr,Mg) ₃ ( _PO4 ) ₃ :Sn, _La2O2S :Eu _, and _{Y2O2S : Eu} . Furthermore, examples of wavelength conversion materials that are excited by ultraviolet light and emit green light include green-emitting phosphor particles, and more specifically, _LaPO4 :Ce, Tb, _BaMgAl10O17 :Eu, Mn, _Zn2SiO4 : _Mn , _MgAl11O19 : _{Ce ,} Tb, _Y2SiO5 :Ce, _Tb , _MgAl11O19 :CE, Tb, _Mn , and _{Si6 - ZAlZOZN8 -Z} :Eu. Furthermore, as wavelength conversion materials excited by ultraviolet light and emitting blue light, specifically, _blue light _emitting phosphor particles, more specifically, _BaMgAl10O17 :Eu, _BaMg2Al16O27 :Eu, _Sr2P2O7 :Eu, _Sr5 ( _PO4 ) _3Cl :Eu, ( _Sr , _Ca , _Ba ,Mg) ₅ ( _PO4 ) _3Cl :Eu, _CaWO4 , _CaWO4 :Pb can be mentioned. Furthermore, as wavelength conversion materials excited by ultraviolet light and emitting yellow light, specifically, yellow light emitting phosphor particles, more specifically, YAG phosphor particles can be mentioned. The wavelength conversion material may be one type, or two or more types may be mixed and used. Furthermore, by using a mixture of two or more types of wavelength converting materials, it is possible to configure the wavelength converting material mixture to emit light of a color other than yellow, green, and red. Specifically, it may be configured to emit cyan light, and in this case, a mixture of the above-mentioned green light-emitting phosphor particles and blue light-emitting phosphor particles may be used.

However, wavelength conversion materials (color conversion materials) are not limited to phosphor particles, and examples of such materials include indirect transition type silicon-based materials, and luminescent particles that use quantum well structures such as two-dimensional quantum well structures, one-dimensional quantum well structures (quantum wires), and zero-dimensional quantum well structures (quantum dots) that localize the wave function of carriers and use quantum effects to efficiently convert carriers into light, as in the case of direct transition types. It is also known that rare earth atoms added to semiconductor materials emit light sharply due to intrashell transitions, and luminescent particles that use such technologies can also be mentioned.

As described above, quantum dots can be cited as wavelength conversion materials (color conversion materials). As the size (diameter) of a quantum dot becomes smaller, the band gap energy becomes larger, and the wavelength of light emitted from the quantum dot becomes shorter. That is, the smaller the size of a quantum dot, the shorter the wavelength of light (light on the blue light side) that it emits, and the larger the size, the longer the wavelength of light (light on the red light side) that it emits. Therefore, by using the same material to compose the quantum dot and adjusting the size of the quantum dot, it is possible to obtain quantum dots that emit light having a desired wavelength (color conversion to a desired color). Specifically, the quantum dots preferably have a core-shell structure. Examples of materials constituting quantum dots include Si; Se; chalcopyrite compounds such as CIGS (CuInGaSe), CIS (CuInSe ₂ ), CuInS ₂ , CuAlS ₂ , CuAlSe ₂ , CuGaS 2 , CuGaSe ₂ , AgAlS _{2 , AgAlSe 2 ,} AgInS ₂ , and AgInSe ₂ ; perovskite materials; III-V compounds such as GaAs, GaP, InP, InAs, InGaAs, AlGaAs, _InGaP , AlGaInP, InGaAsP, and GaN; CdSe, CdSeS, CdS, CdTe, In ₂ Se ₃ , In ₂ S ₃ , Bi ₂ Se ₃ , and Bi ₂ S. ₃ , ZnSe, ZnTe, ZnS, HgTe, HgS, PbSe, PbS, _TiO2 , etc., but are not limited to these.

The present disclosure may also be configured as follows.
[A01] "Light-emitting element"
a first compound semiconductor layer having a first surface and a second surface opposite to the first surface;
an active layer facing the second surface of the first compound semiconductor layer; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposite to the first surface;
A laminated structure in which
A first light reflecting layer formed on the first surface side of the first compound semiconductor layer;
a second light reflecting layer formed on the second surface side of the second compound semiconductor layer;
a first electrode electrically connected to the first compound semiconductor layer; and
a second electrode provided between the second compound semiconductor layer and the second light reflecting layer;
It is equipped with
The second electrode is a light-emitting element having at least a nanocarbon material layer or a two-dimensional material layer.
[A02] The light-emitting element according to [A01], wherein the nanocarbon material layer is made of at least one material selected from the group consisting of graphene, carbon nanotubes, and fullerenes.
[A03] The light-emitting element according to [A01], wherein the two-dimensional material layer is made of at least one material selected from the group consisting of silicene, germanene, boron nitride, and transition metal dichalcogenide-based materials.
[A04] The light-emitting element according to [A03], wherein the transition metal dichalcogenide material is represented by _MX2 , the transition metal "M" is one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Tc and Re, and the chalcogen element "X" is one element selected from the group consisting of O, S, Se and Te.
[A05] The light-emitting element described in any one of [A01] to [A04], wherein the second electrode has a laminated structure of at least a first layer made of a transparent conductive material or a semiconductor material and a second layer made of a nanocarbon material layer or a two-dimensional material layer.
[A06] The light-emitting device according to [A05], wherein the first layer is in contact with the second compound semiconductor layer.
[A07] The light-emitting element according to [A05] or [A06], in which the second layer is not formed in the central portion of the second electrode.
[A08] When the distance in the thickness direction of the laminated structure from the center of the active layer in the thickness direction to the center of the nanocarbon material layer or the two-dimensional material layer in the thickness direction is L ₂ , the oscillation wavelength is λ ₀ , and the equivalent refractive index of the part located from the center of the active layer in the thickness direction to the center of the nanocarbon material layer or the two-dimensional material layer in the thickness direction is n _eq ,
0.9×{(m+1)λ ₀ )/(4・n _eq )}≦L ₂ ≦1.1×{(m+1)λ ₀ )/(4・n _eq )}
The light-emitting element according to any one of [A01] to [A06], which satisfies the above.
Here, m is an arbitrary integer of 2 or more, including 0 or 1.
[A09] The light-emitting element according to any one of [A01] to [A08], wherein the thickness of the nanocarbon material layer or the two-dimensional material layer constituting the second electrode is greater than 0 nm and is 5 nm or less.
[A10] At least a portion of the second compound semiconductor layer in the thickness direction is composed of a current injection region and a current non-injection region surrounding the current injection region,
The light-emitting device according to any one of [A01] to [A09], wherein the diameter of the current injection region in the second surface of the second compound semiconductor layer is 1×10 ⁻⁶ m to 1×10 ⁻² m, preferably 2×10 ⁻⁶ m to 1×10 ⁻³ m.
[A11] The second compound semiconductor layer is partitioned into a first region and a second region surrounding the first region,
a second electrode is provided on the first region of the second compound semiconductor layer;
The light-emitting element according to any one of [A01] to [A09], wherein the second region of the second compound semiconductor layer faces the second electrode via an insulating layer.
[A12] The light-emitting device according to any one of [A01] to [A11], in which a plurality of grooves extending in one direction are formed in the second electrode.
[A13] The first light reflective layer has a convex shape extending in a direction away from the active layer,
The light-emitting device according to any one of [A01] to [A12], wherein the second light reflective layer has a flat shape.
[A14] The light-emitting element according to [A13], wherein the radius of curvature of the portion of the first light reflecting layer having a convex shape is 1×10 ⁻⁵ m to 1×10 ⁻² m.
[A15] The light-emitting element according to [A13] or [A14], wherein the cavity length is 1×10 ⁻⁶ m to 5×10 ⁻⁴ m.
[B01] The light-emitting element according to any one of [A01] to [A15], in which a partition wall extending in the stacking direction of the stacked structure is formed so as to surround the first light reflecting layer.
[B02] The light-emitting element according to [B01], wherein the partition wall extends from the first surface side of the first compound semiconductor layer, within the first compound semiconductor layer, to a midpoint in a thickness direction of the first compound semiconductor layer.
[B03] The light-emitting element according to [B01], wherein the partition extends from the second surface side of the second compound semiconductor layer into the second compound semiconductor layer and the active layer, and further extends into the first compound semiconductor layer to a midpoint in a thickness direction of the first compound semiconductor layer.
[B04] The light-emitting element according to any one of [B01] to [B03], wherein the partition is made of a material that does not transmit light generated in the active layer.
[B05] The light-emitting element according to any one of [B01] to [B04], wherein the partition is made of a material that reflects light generated in the active layer.
[B06] When the thermal conductivity of the material constituting the first compound semiconductor layer is TC ₁ and the thermal conductivity of the material constituting the partition wall is TC ₀ ,
1×10 ^-1 ≦TC ₁ /TC ₀ ≦1×10 ²
The light-emitting element according to any one of [B01] to [B05], which satisfies the above.
[B07] When the linear expansion coefficient of the material constituting the first compound semiconductor layer is CTE ₁ and the linear expansion coefficient of the material constituting the partition wall is CTE ₀ ,
｜CTE ₀ -CTE ₁ ｜≦1×10 ^-4 /K
The light-emitting element according to any one of [B01] to [B06], which satisfies the above.
[B08] The partition is made of a solder material,
The light-emitting element according to any one of [B01] to [B07], wherein a part of the partition is exposed to an outer surface of the light-emitting element.
[B09] The light-emitting element according to any one of [B01] to [B08], wherein a side surface of the partition narrows in a direction from the first surface side of the first compound semiconductor layer toward the second surface side of the second compound semiconductor layer.
[B10] The first light reflecting layer is formed on a base surface located on the first surface side of the first compound semiconductor layer,
The base surface extends to a peripheral region;
The light-emitting element according to any one of [B01] to [B09], wherein the base surface is uneven and differentiable.
[C01] A base surface located on the first surface side of the first compound semiconductor layer is composed of a first portion and a second portion (peripheral region) surrounding the first portion,
a first light reflecting layer formed on the first portion;
The light-emitting element according to any one of [A01] to [B10], wherein the first portion is convex and the second portion is concave with respect to the second surface of the first compound semiconductor layer, and the light-emitting element is differentiable from the first portion to the second portion.
[C02] The light-emitting element according to [C01], wherein the base surface is smooth.
[C03] The light-emitting element according to [C01] or [C02], wherein a first portion of a base surface on which a first light-reflecting layer is formed has an upwardly convex shape when the second surface of the first compound semiconductor layer is used as a reference.
[C04] Light-emitting element of A-configuration
The light-emitting device according to [C03], wherein the second portion of the base surface occupying the peripheral region has a downwardly convex shape when the second surface of the first compound semiconductor layer is taken as a reference.
[C05] The light-emitting element according to [C04], wherein the center of the first portion of the base surface is located on an apex (intersection) of a square lattice.
[C06] The light-emitting element according to [C04], wherein the center of the first portion of the base surface is located on an apex (intersection) of a lattice of equilateral triangles.
[C07]《Light-emitting element of configuration B》
The light-emitting device according to [C03], wherein, when the second surface of the first compound semiconductor layer is used as a reference, the second portion of the base surface occupying the peripheral region has a downward convex shape toward a center of the peripheral region, and an upward convex shape extending from the downward convex shape.
[C08] When the distance from the second surface of the first compound semiconductor layer to the center of the first portion of the base surface is LL ₁ and the distance from the second surface of the first compound semiconductor layer to the center of the second portion of the base surface is LL ₂ ,
_LL2 > _LL1
The light-emitting element according to [C07], which satisfies the above.
[C09] When the radius of curvature of the center of the first portion of the base surface (i.e., the radius of curvature of the first light reflecting layer) is R ₁ and the radius of curvature of the center of the second portion of the base surface is R ₂ ,
_R1 > _R2
The light-emitting element according to [C07] or [C08], which satisfies the following:
[C10] The light-emitting element according to any one of [C07] to [C09], wherein the center of the first portion of the base surface is located on an apex (intersection) of a square lattice.
[C11] The light-emitting device according to [C10], wherein the center of the second portion of the base surface is located on an apex (intersection) of a square lattice.
[C12] The light-emitting element according to any one of [C07] to [C09], wherein the center of the first portion of the base surface is located on an apex (intersection) of an equilateral triangular lattice.
[C13] The light-emitting device according to [C12], wherein the center of the second portion of the base surface is located on an apex (intersection) of a lattice of equilateral triangles.
[C14] The light-emitting element according to any one of [C07] to [C13], wherein the radius of curvature _R2 of the central portion of the second portion of the base surface is 1×10 ⁻⁶ m or more, preferably 3×10 ⁻⁶ m or more, and more preferably 5×10 ⁻⁶ m or more.
[C15]《Light-emitting element of configuration C》
The light-emitting element according to [C03], wherein, when the second surface of the first compound semiconductor layer is used as a reference, the second portion of the base surface occupying the peripheral region has an annular convex shape surrounding the first portion of the base surface, and a downwardly convex shape extending from the annular convex shape toward the first portion of the base surface.
[C16] When the distance from the second surface of the first compound semiconductor layer to the center of the first portion of the base surface is LL ₁ and the distance from the second surface of the first compound semiconductor layer to the top of the annular convex shape of the second portion of the base surface is LL ₂ ',
_LL2 '> _LL1
The light-emitting element according to [C15], which satisfies the above.
[C17] When the radius of curvature of the center of the first portion of the base surface (i.e., the radius of curvature of the first light reflecting layer) is R ₁ and the radius of curvature of the apex of the annular convex shape of the second portion of the base surface is R ₂ ',
R ₁ >R ₂ '
The light-emitting element according to [C15] or [C16], which satisfies the following:
[C18] The light-emitting element according to any one of [C15] to [C17], wherein the radius of curvature _R2 ' of the apex of the annular convex shape of the second portion of the base surface is 1 x ^10-6 m or more, preferably 3 x ^10-6 m or more, and more preferably 5 x ^10-6 m or more.
[C19] The light-emitting element according to any one of [C07] to [C18], wherein a bump is provided on a portion of the second surface side of the second compound semiconductor layer that faces the convex-shaped portion in the second portion of the base surface.
[C20] The light-emitting element according to any one of [C04] to [C06], wherein a bump is provided on a portion of the second surface side of the second compound semiconductor layer opposite the center of the first portion of the base surface.
[C21] The light-emitting element according to any one of [C01] to [C20], in which the formation pitch of the light-emitting elements is 3 μm or more and 50 μm or less, preferably 5 μm or more and 30 μm or less, and more preferably 8 μm or more and 25 μm or less.
[C22] The light-emitting element according to any one of [C01] to [C21], wherein the radius of curvature R ₁ of the center of the first portion of the base surface (i.e., the radius of curvature of the first light reflecting layer) is 1×10 ^-4 m or more, preferably 3×10 ^-4 m or more.
[C23] The light-emitting element according to any one of [A01] to [C22], wherein the laminated structure is made of at least one material selected from the group consisting of GaN-based compound semiconductors, InP-based compound semiconductors, and GaAs-based compound semiconductors.
[C24] The light-emitting device according to any one of [C01] to [C23], wherein, when a cavity length is L _OR , 1×10 ⁻⁶ m≦L _OR is satisfied.
[C25] A light-emitting element described in any one of [A01] to [C24], in which the figure drawn by the first part of the base surface when the base surface is cut by a virtual plane including the stacking direction of the laminated structure is part of a circle or part of a parabola.
[C26] The light-emitting device according to any one of [A01] to [C25], in which the first surface of the first compound semiconductor layer constitutes a base surface.
[C27] A light-emitting element described in any one of [A01] to [C25], wherein a compound semiconductor substrate is disposed between the first surface of the first compound semiconductor layer and the first light reflecting layer, and the base surface is composed of the surface of the compound semiconductor substrate.
[C28] A light-emitting element according to any one of [A01] to [C25], wherein a base material is disposed between the first surface of the first compound semiconductor layer and the first light reflecting layer, or a compound semiconductor substrate and a base material are disposed between the first surface of the first compound semiconductor layer and the first light reflecting layer, and the base surface is composed of the surface of the base material.
[C29] The light-emitting element according to [C28], wherein the material constituting the substrate is at least one material selected from the group consisting of transparent dielectric materials such as _TiO2 , _Ta2O5 , _SiO2 , silicone-based resins, and epoxy _- based resins.
[C30] The light-emitting element according to any one of [A01] to [C29], in which a first light-reflecting layer is formed on a base surface.
[C31] The light-emitting element according to any one of [A01] to [C30], wherein the thermal conductivity value of the stacked structure is higher than the thermal conductivity value of the first light reflecting layer.
[D01] The second compound semiconductor layer is provided with a current injection region and a current non-injection region surrounding the current injection region,
The light-emitting element according to any one of [A01] to [C31], wherein the shortest distance D _CI from the center of gravity of the current injection region to the boundary between the current injection region and the non-current injection region satisfies the following formula:
_DCI ≧ _ω0 /2
however,
ω ₀ ² ≡ (λ ₀ /π) {L _OR (R ₁ - L _OR )} ^1/2
Where:
λ ₀ : the wavelength of the desired light mainly emitted from the light emitting element (oscillation wavelength)
L _OR : Resonator length R ₁ : Radius of curvature of the center of the first portion of the base surface (i.e., radius of curvature of the first light reflecting layer)
[D02] A mode loss action portion provided on the second surface of the second compound semiconductor layer and constituting a mode loss action region acting to increase or decrease the oscillation mode loss;
a second electrode formed on the second surface of the second compound semiconductor layer and on the mode loss active portion; and
a first electrode electrically connected to the first compound semiconductor layer;
It further comprises:
The second light reflective layer is formed on the second electrode,
The laminated structure includes a current injection region and a non-current injection region surrounding the current injection region,
The light-emitting element according to [D01], wherein an orthogonal projection image of the mode loss effect region and an orthogonal projection image of the current non-injection region overlap with each other.
[D03] The radius r ₁ of the effective light reflection area of the first light reflecting layer is
ω ₀ ≦r ₁ ≦20・ω ₀
The light-emitting element according to [D01] or [D02], which satisfies the above.
[D04] The light-emitting element according to any one of [D01] to [D03], which satisfies D _CI ≧ _ω0 .
[D05] The light-emitting element according to any one of [D01] to [D04], which satisfies R ₁ ≦1×10 ⁻² m.
[E01] A mode loss action portion provided on the second surface of the second compound semiconductor layer and constituting a mode loss action region acting to increase or decrease the oscillation mode loss;
a second electrode formed on the second surface of the second compound semiconductor layer and on the mode loss active portion; and
a first electrode electrically connected to the first compound semiconductor layer;
It further comprises:
The second light reflective layer is formed on the second electrode,
The laminated structure includes a current injection region and a non-current injection region surrounding the current injection region,
The light-emitting element according to any one of [A01] to [C31], wherein an orthogonal projection image of the mode loss effect region and an orthogonal projection image of the current non-injection region overlap with each other.
[E02] The light-emitting element according to [E01], wherein the current non-injection region is located below the mode loss active region.
[E03] When the area of the projection image of the current injection region is _S1 and the area of the projection image of the current non-injection region is _S2 ,
0.01≦S ₁ /(S ₁ +S ₂ )≦0.7
The light-emitting element according to [E01] or [E02], which satisfies the following:
[E04] The light-emitting element according to any one of [E01] to [E03], wherein the current non-injection region is formed by ion implantation into the stacked structure.
[E05] The light-emitting element according to [E04], wherein the ion species is at least one type of ion selected from the group consisting of boron, proton, phosphorus, arsenic, carbon, nitrogen, fluorine, oxygen, germanium, and silicon.
[E06] The light-emitting element according to any one of [E01] to [E05], wherein the current non-injection region is formed by plasma irradiation of the second surface of the second compound semiconductor layer, or by ashing treatment of the second surface of the second compound semiconductor layer, or by reactive ion etching treatment of the second surface of the second compound semiconductor layer.
[E07] A light-emitting element described in any one of [E01] to [E06], wherein the second light-reflecting layer has a region that reflects or scatters light from the first light-reflecting layer toward the outside of the resonator structure formed by the first light-reflecting layer and the second light-reflecting layer.
[E08] When the optical distance from the active layer in the current injection region to the second surface of the second compound semiconductor layer is OL ₂ and the optical distance from the active layer in the mode loss action region to the top surface of the mode loss action portion is OL ₀ ,
Office Lady ₀ > Office Lady ₂
The light-emitting element according to any one of [E01] to [E07], which satisfies the above.
[E09] A light-emitting element described in any one of [E01] to [E08], in which the generated light having a higher mode is dissipated by the mode loss effect region toward the outside of the resonator structure formed by the first light reflecting layer and the second light reflecting layer, thereby increasing the oscillation mode loss.
[E10] The light-emitting element according to any one of [E01] to [E09], wherein the mode loss active portion is made of a dielectric material, a metal material, or an alloy material.
[E11] The mode loss active portion is made of a dielectric material,
The light-emitting element according to [E10], wherein the optical thickness of the mode loss effect portion is a value outside of an integer multiple of ¼ of the wavelength of the light generated in the light-emitting element array.
[E12] The mode loss effect portion is made of a dielectric material,
The light-emitting element according to [E10], wherein the optical thickness of the mode loss effect portion is an integer multiple of ¼ of the wavelength of the light generated in the light-emitting element array.
[E13]
A convex portion is formed on the second surface side of the second compound semiconductor layer,
The light-emitting device according to any one of [E01] to [E03], wherein the mode loss effect portion is formed on a region of the second surface of the second compound semiconductor layer that surrounds the convex portion.
[E14] When the optical distance from the active layer in the current injection region to the second surface of the second compound semiconductor layer is OL ₂ and the optical distance from the active layer in the mode loss action region to the top surface of the mode loss action portion is OL ₀ ,
Office Lady ₀ < Office Lady ₂
The light-emitting element according to [E13], which satisfies the above.
[E15] The light-emitting element according to [E13] or [E14], wherein the generated light having a higher mode is confined to the current injection region and the current non-injection region by the mode loss effect region, thereby reducing oscillation mode loss.
[E16] The light-emitting element according to any one of [E13] to [E15], wherein the mode loss active portion is made of a dielectric material, a metal material, or an alloy material.
[E17] The light-emitting element according to any one of [E01] to [E16], in which the second electrode is made of a transparent conductive material.
[F01] A second electrode formed on the second surface of the second compound semiconductor layer;
a second light reflective layer formed on the second electrode;
a mode loss effect portion provided on the first surface of the first compound semiconductor layer and constituting a mode loss effect region that acts to increase or decrease the oscillation mode loss; and
a first electrode electrically connected to the first compound semiconductor layer;
It further comprises:
the first light reflecting layer is formed over the first surface of the first compound semiconductor layer and over the mode loss active portion;
The laminated structure includes a current injection region and a non-current injection region surrounding the current injection region,
The light-emitting element according to any one of [A01] to [C31], wherein an orthogonal projection image of the mode loss effect region and an orthogonal projection image of the current non-injection region overlap with each other.
[F02] When the area of the projection image of the current injection region is S ₁ and the area of the projection image of the current non-injection region is S ₂ ,
0.01≦S ₁ '/(S ₁ '+S ₂ ')≦0.7
The light-emitting element according to [F01], which satisfies the above.
[F03] The light-emitting element according to [F01] or [F02], wherein the current non-injection region is formed by ion implantation into the laminated structure.
[F04] The light-emitting element according to [F03], wherein the ion species is at least one type of ion selected from the group consisting of boron, proton, phosphorus, arsenic, carbon, nitrogen, fluorine, oxygen, germanium and silicon.
[F05] The light-emitting element according to any one of [F01] to [F04], wherein the current non-injection region is formed by plasma irradiation of the second surface of the second compound semiconductor layer, or by ashing treatment of the second surface of the second compound semiconductor layer, or by reactive ion etching treatment of the second surface of the second compound semiconductor layer.
[F06] A light-emitting element described in any one of [F01] to [F05], wherein the second light reflecting layer has a region that reflects or scatters light from the first light reflecting layer toward the outside of a resonator structure formed by the first light reflecting layer and the second light reflecting layer.
[F07] When the optical distance from the active layer in the current injection region to the first surface of the first compound semiconductor layer is OL ₁ ', and the optical distance from the active layer in the mode loss action region to the top surface of the mode loss action portion is OL ₀ ',
OL ₀ '＞OL ₁ '
The light-emitting element according to any one of [F01] to [F06], which satisfies the above.
[F08] The light-emitting element according to any one of [F01] to [F07], wherein the generated light having a higher mode is dissipated by the mode loss effect region toward the outside of the resonator structure formed by the first light reflecting layer and the second light reflecting layer, thereby increasing the oscillation mode loss.
[F09] The light-emitting element according to any one of [F01] to [F08], wherein the mode loss active portion is made of a dielectric material, a metal material, or an alloy material.
[F10] The mode loss active portion is made of a dielectric material,
The light-emitting element according to [F09], wherein the optical thickness of the mode loss effect portion is a value outside of an integer multiple of ¼ of the wavelength of the light generated in the light-emitting element array.
[F11] The mode loss active portion is made of a dielectric material,
The light-emitting element according to [F09], wherein the optical thickness of the mode loss effect portion is an integer multiple of ¼ of the wavelength of the light generated in the light-emitting element array.
[F12] A convex portion is formed on the first surface side of the first compound semiconductor layer,
The light-emitting device according to [F01] or [F02], wherein the mode loss effect portion is formed on a region of the first surface of the first compound semiconductor layer that surrounds the convex portion.
[F13] When the optical distance from the active layer in the current injection region to the first surface of the first compound semiconductor layer is OL ₁ ', and the optical distance from the active layer in the mode loss action region to the top surface of the mode loss action portion is OL ₀ ',
OL ₀ '＜OL ₁ '
The light-emitting element according to [F12], which satisfies the above.
[F14] A convex portion is formed on the first surface side of the first compound semiconductor layer,
The light-emitting device according to [F01] or [F02], wherein the mode loss active portion is constituted by a region of the first surface of the first compound semiconductor layer surrounding the convex portion.
[F15] A light-emitting element according to any one of [F12] to [F14], in which the generated light having a higher mode is confined to the current injection region and the current non-injection region by the mode loss effect region, thereby reducing oscillation mode loss.
[F16] The light-emitting device according to any one of [F12] to [F15], wherein the mode loss active portion is made of a dielectric material, a metal material or an alloy material.
[F17] The light-emitting element according to any one of [F01] to [F16], wherein the second electrode is made of a transparent conductive material.
[G01] A light-emitting element according to any one of [A01] to [F17], in which at least two light-absorbing material layers are formed in the stacked structure including the second electrode parallel to a virtual plane occupied by the active layer.
[G02] The light-emitting element according to [G01], in which at least four light-absorbing material layers are formed.
[G03] When the oscillation wavelength is λ ₀ , the equivalent refractive index of the entire two light absorbing material layers and the portion of the laminated structure located between the light absorbing material layers is n _eq , and the distance between the light absorbing material layers is L _Abs ,
0.9×{(m・λ ₀ )/(2・n _eq )}≦L _Abs ≦1.1×{(m・λ ₀ )/(2・n _eq )}
The light-emitting element according to [G01] or [G02], which satisfies the above.
Here, m is 1 or any integer of 2 or more including 1.
[G04] The light-emitting element according to any one of [G01] to [G03], wherein the thickness of the light-absorbing material layer is λ ₀ /(4·n _eq ) or less.
[G05] The light-emitting element according to any one of [G01] to [G04], in which the light-absorbing material layer is located in a minimum amplitude portion occurring in a standing wave of light formed inside the laminated structure.
[G06] The light-emitting element according to any one of [G01] to [G05], in which the active layer is located in a maximum amplitude portion of a standing wave of light formed inside the laminated structure.
[G07] The light-emitting element according to any one of [G01] to [G06], wherein the light-absorbing material layer has a light absorption coefficient that is at least twice as high as the light absorption coefficient of the compound semiconductor that constitutes the stacked structure.
[G08] The light-emitting element according to any one of [G01] to [G07], wherein the light-absorbing material layer is composed of at least one material selected from the group consisting of a compound semiconductor material having a narrower band gap than the compound semiconductor constituting the laminated structure, a compound semiconductor material doped with impurities, a transparent conductive material, and a light-reflecting layer constituent material having light-absorbing properties.
[H01] <<Method of manufacturing a light-emitting element array>>
a first compound semiconductor layer having a first surface and a second surface opposite to the first surface;
an active layer facing the second surface of the first compound semiconductor layer; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposite to the first surface;
A laminated structure in which
a first light reflecting layer formed on a base surface located on the first surface side of the first compound semiconductor layer; and
a second light reflecting layer formed on the second surface side of the second compound semiconductor layer and having a flat shape;
It is equipped with
The base surface extends to a peripheral region surrounded by the plurality of light emitting elements;
A method for manufacturing a light-emitting element array including a plurality of light-emitting elements, the base surface of which is uneven and differentiable, the method comprising the steps of:
After forming the laminated structure, a second light reflecting layer is formed on the second surface side of the second compound semiconductor layer, and then
forming a first sacrificial layer on a first portion of the base surface on which the first light reflecting layer is to be formed, and then forming a convex surface of the first sacrificial layer;
forming a second sacrificial layer on a second portion of the base surface exposed between the first sacrificial layer and on the first sacrificial layer to provide an irregular surface of the second sacrificial layer; and
the second sacrificial layer and the first sacrificial layer are etched back, and further etched back inward from the base surface, thereby forming a convex portion on the first portion of the base surface and at least a concave portion on the second portion of the base surface when the second surface of the first compound semiconductor layer is used as a reference, and then
forming a first light reflective layer over a first portion of the base surface;
A method for manufacturing a light-emitting element array comprising each step.
[H02] "Method of manufacturing a light-emitting element array"
a first compound semiconductor layer having a first surface and a second surface opposite to the first surface;
an active layer facing the second surface of the first compound semiconductor layer; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposite to the first surface;
A laminated structure in which
a first light reflecting layer formed on a base surface located on the first surface side of the first compound semiconductor layer; and
a second light reflecting layer formed on the second surface side of the second compound semiconductor layer and having a flat shape;
Equipped with
The base surface extends to a peripheral region surrounded by the plurality of light emitting elements;
A method for manufacturing a light-emitting element array including a plurality of light-emitting elements, the base surface of which is uneven and differentiable, the method comprising the steps of:
After forming the laminated structure, a second light reflecting layer is formed on the second surface side of the second compound semiconductor layer, and then
forming a first sacrificial layer on a first portion of the base surface on which the first light reflecting layer is to be formed, and then forming a convex surface of the first sacrificial layer;
The first sacrificial layer is etched back, and further etched back inward from the base surface to form a convex portion on the first portion of the base surface when the second surface of the first compound semiconductor layer is used as a reference.
After forming a second sacrificial layer on the base surface, the second sacrificial layer is etched back, and then etched back further from the base surface toward the inside, thereby forming a convex portion on a first portion of the base surface and at least a concave portion on a second portion of the base surface when the second surface of the first compound semiconductor layer is used as a reference, and then
forming a first light reflective layer over a first portion of the base surface;
A method for manufacturing a light-emitting element array comprising each step.
[H03] <<Method of manufacturing a light-emitting element array>>
a first compound semiconductor layer having a first surface and a second surface opposite to the first surface;
an active layer facing the second surface of the first compound semiconductor layer; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposite to the first surface;
A laminated structure in which
a first light reflecting layer formed on a base surface located on the first surface side of the first compound semiconductor layer; and
a second light reflecting layer formed on the second surface side of the second compound semiconductor layer and having a flat shape;
It is equipped with
The base surface extends to a peripheral region surrounded by the plurality of light emitting elements;
A method for manufacturing a light-emitting element array including a plurality of light-emitting elements, the base surface of which is uneven and differentiable, the method comprising the steps of:
Providing a mold having a surface complementary to the base surface;
After forming the laminated structure, a second light reflecting layer is formed on the second surface side of the second compound semiconductor layer, and then
A sacrificial layer is formed on a base surface on which a first light reflecting layer is to be formed, and then a shape of a surface complementary to the base surface of the mold is transferred to the sacrificial layer to form a concave-convex portion on the sacrificial layer.
The sacrificial layer is etched back, and further etched back inward from the base surface, so that, when the second surface of the first compound semiconductor layer is taken as a reference, a convex portion is formed on a first portion of the base surface and at least a concave portion is formed on a second portion of the base surface.
forming a first light reflective layer over a first portion of the base surface;
A method for manufacturing a light-emitting element array comprising each step.

10A, 10A', 10B, 10C, 10D, 10E, 10F, 10G, 10H... Light emitting element (surface emitting element, surface emitting laser element), 11... Compound semiconductor substrate (substrate for manufacturing a light emitting element array), 20... Laminated structure, 21... First compound semiconductor layer, 21a... First surface of the first compound semiconductor layer, 21b... Second surface of the first compound semiconductor layer, 22... Second compound semiconductor layer, 22a... First surface of the second compound semiconductor layer, 22b... Second surface of the second compound semiconductor layer, 23... Active layer (light emitting layer), 24, 25A, 25B, 25C, 25D... Partition wall, 24', 25'... Side surface of partition wall, 25D ': part of partition wall, 26: light absorbing material layer, 31: first electrode, 31': opening provided in first electrode, 32: second electrode, 33: second pad electrode, 34: insulating layer (current confinement layer), 34A: opening provided in insulating layer (current confinement layer), 35: bump, 41: first light reflecting layer, 42: second light reflecting layer, 48: bonding layer, 49: supporting substrate, 51: current injection region, 52: current non-injection region, 81, 81': first sacrificial layer, 82: second sacrificial layer, 83, 83': part of first sacrificial layer for forming center of second portion, 90: base surface, 90 _bd : boundary between first and second portions, 91: first portion of base surface, 91': convex portion formed on first portion of base surface, 91A: convex portion formed on first portion of base surface, _91c : center portion of first portion of base surface, 92: second portion of base surface, 92A: concave portion formed on second portion of base surface, _92c : center portion of second portion of base surface, _92b : portion having a downward convex shape on second portion of base surface, 93: annular convex shape surrounding first portion of base surface, 94A: downward convex shape extending from annular convex shape toward first portion of base surface, 94B: region surrounded by annular convex shape on second portion of base surface, 95: substrate, 96: concave portion for forming base surface, 97: planarizing film, 99: peripheral region

Claims (15)

a first compound semiconductor layer having a first surface and a second surface opposite to the first surface;
an active layer facing the second surface of the first compound semiconductor layer; and
a second compound semiconductor layer having a first surface facing the active layer and a second surface opposite to the first surface;
A laminated structure in which
A first light reflecting layer formed on the first surface side of the first compound semiconductor layer;
a second light reflecting layer formed on the second surface side of the second compound semiconductor layer;
a first electrode electrically connected to the first compound semiconductor layer; and
a second electrode provided between the second compound semiconductor layer and the second light reflecting layer;
Equipped with
The second electrode is a light emitting device having at least a two- dimensional layer of material. the second electrode further comprises a nanocarbon material layer;
The light-emitting device according to claim 1 , wherein the nano-carbon material layer is made of at least one material selected from the group consisting of graphene, carbon nanotubes, and fullerene. The light-emitting device according to claim 1, wherein the two-dimensional material layer is made of at least one material selected from the group consisting of silicene, germanene, boron nitride, and transition metal dichalcogenide-based materials. 4. The light-emitting device according to claim ₃ , wherein the transition metal dichalcogenide material is represented by MX2, the transition metal "M" is one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Mo, W, Tc and Re, and the chalcogen element "X" is one element selected from the group consisting of O, S, Se and Te. The light-emitting element according to claim 1 , wherein the second electrode has a laminated structure of at least a first layer made of a transparent conductive material or a semiconductor material and a second layer made of a two-dimensional material layer. The light-emitting device according to claim 5, wherein the first layer is in contact with the second compound semiconductor layer. The light-emitting element according to claim 5, in which the second layer is not formed in the center of the second electrode. When the distance in the thickness direction of the laminated structure from the center of the active layer in the thickness direction to the center of the two -dimensional material layer in the thickness direction is L ₂ , the oscillation wavelength is λ ₀ , and the equivalent refractive index of the portion located from the center of the active layer in the thickness direction to the center of the two- dimensional material layer in the thickness direction is n _eq ,
0.9×{(m+1)λ ₀ )/(4・_neq )}≦L ₂ ≦1.1×{(m+1)λ ₀ )/(4・_neq )}
The light emitting device according to claim 1 , which satisfies the following:
Here, m is an arbitrary integer of 2 or more, including 0 or 1. The light-emitting device according to claim 1 , wherein the thickness of the two- dimensional material layer constituting the second electrode is greater than 0 nm and is not greater than 5 nm. At least a portion of the second compound semiconductor layer in a thickness direction is composed of a current injection region and a current non-injection region surrounding the current injection region,
2. The light emitting device according to claim 1, wherein the diameter of the current injection region in the second surface of the second compound semiconductor layer is 1×10 ⁻⁶ m to 1×10 ⁻² m. the second compound semiconductor layer is partitioned into a first region and a second region surrounding the first region;
a second electrode is provided on the first region of the second compound semiconductor layer;
The light-emitting device according to claim 1 , wherein the second region of the second compound semiconductor layer faces the second electrode via an insulating layer. The light-emitting element according to claim 1, wherein the second electrode has a plurality of grooves extending in one direction. the first light reflecting layer has a convex shape extending in a direction away from the active layer,
The light-emitting device according to claim 1 , wherein the second light-reflecting layer has a flat shape. The light-emitting element according to claim 13, wherein the radius of curvature of the portion of the first light-reflecting layer having a convex shape is 1×10 ⁻⁵ m to 1×10 ⁻² m. 14. The light emitting device according to claim 13, wherein the cavity length is 1×10 ⁻⁶ m to 5×10 ⁻⁴ m.

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