JP2000307195A - Semiconductor light emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light emitting element, such as a high- output red semiconductor laser which stably oscillates in 635-nm band, 650-nm band, etc., at a high temperature, a visible semiconductor laser which oscillates at a wavelength shorter than 600 nm at a room temperature, a visible light emitting diode having a high luminous efficiency, etc. SOLUTION: The active layer 2 of a semiconductor light emitting element is composed of (AlxGa1-x)αIn1-αPtAs1-t (0<=x<1, 0<α<=1, 0<=t<1) and the clad layers 3 of the element are composed of (AlyGa1-y)βIn1-βPvAs1-v (0<y<=1, 0.5<β<1, 0<v<=1) having a band gap larger than that of the active layer 2 and containing Al having a lattice constant between those of GaP and GaAs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor light emitting device.

[0002]

2. Description of the Related Art AlGaInP-based materials are known as AlGaIn.
Except for N-based materials and B (boron) -based materials, it is the largest direct transition type material among III-V semiconductors, and has a band gap energy of about 2.3 eV at maximum (wavelength 540).
nm). For this reason, research and development have been carried out as materials for light emitting elements such as high-brightness green to red light emitting diodes conventionally used for color displays and the like and visible light semiconductor lasers used for optical writing of laser printers, CDs, DVDs and the like. Have been. Among these, a material that lattice-matches with a GaAs substrate is used for a semiconductor laser. Particularly for high-density recording and the like, an element that operates stably at high temperature and high output and has a short wavelength is required.

In order to fabricate a semiconductor laser, a cladding layer (made of a material having a larger band gap than the active layer) is used.
It is necessary to have a structure in which carriers and light are confined in an active layer (light-emitting layer). Double hetero of normal bulk active layer
In the case of a short wavelength with the (DH) structure, it is necessary to use AlGaInP to which Al is added for the active layer. The addition of Al has the effect of increasing the band gap, but since Al is very active, during growth, it combines with a slight amount of oxygen or the like in the atmosphere or in the raw material to form a deep level, leading to a decrease in luminous efficiency. It is preferable that the Al composition is small because it is easy.
Therefore, as another method of shortening the oscillation wavelength, a SCH-QW (Sequence) using a GaInP quantum well structure as an active layer (well layer) and AlGaInP as an optical guide layer is used.
parateConfinement Heterostructure-Quantum Well)
And the method has been done. Further, in order to lower the threshold value, a strained quantum well structure in which a strain is applied to a quantum well layer is generally used as shown in JP-A-6-77592. In this case, since the lattice constant of the strained quantum well layer is different from that of the substrate, a thickness equal to or less than the critical film thickness at which lattice relaxation occurs can be used. Japanese Patent Application Laid-Open No. 6-275915 discloses that tensile strain is more effective as a type of strain for a short wavelength laser such as a 635 nm band. Since the tensile strain well layer becomes GaInP having a composition close to GaP with respect to GaAs as a substrate, the tensile strain well layer has a wide gap, and a well layer having an appropriate thickness can be used as a well layer for the compressive strain well layer. It is considered that the major reason is that the adverse effect of the above can be reduced. However, if a tensile strain well layer is used,
Since the mode is the TM mode, the polarization differs from that of a normal semiconductor laser (TE mode) in another wavelength band by 90 °.

[0004] However, (Al _x Ga _1-x )
Light is confined in the _0.5 In _0.5 P light guide layer. However, since the Al composition x is generally as large as about 0.5, the surface recombination caused by Al at the end face serving as the laser cavity surface causes End face breakage is likely to occur and it is difficult to produce high output, and it is also difficult to operate stably for a long time.

When an AlGaInP-based heterojunction is formed, the band offset ratio of the conduction band is small, and the band discontinuity (Δ) on the conduction band side of the active layer (light emitting layer) and the cladding layer is reduced.
Since Ec) is small, injected carriers (electrons) easily overflow from the active layer to the cladding layer, and there is a problem that the temperature dependence of the oscillation threshold current of the semiconductor laser is large and the temperature characteristics are poor. This problem becomes more pronounced as the wavelength becomes shorter. For example, when compared with red lasers in the 635 nm band and the 650 nm band, the high temperature characteristics of the 635 nm band laser are overwhelmingly poor regardless of the slight wavelength difference.

In order to solve such a problem, Japanese Patent Laid-Open Publication No. Hei. No. 114486. However, in this case, the structure becomes complicated, and in order to obtain the effect, it is necessary to improve the thickness control and to flatten the interface of each layer at the atomic layer level. It was difficult.

As described above, the conventional GaAs substrate lattice-matching material has limitations in temperature characteristics and wavelength reduction.
It has been difficult to realize a laser with a wavelength of 635 nm or shorter, which operates at a high temperature (for example, 80 °), high output (for example, 30 mW or more), and operates stably (for example, 10,000 hours). As described above, AlGaI having a smaller lattice constant than GaAs
Since the nP-based material has a wider gap than a material that can be grown on a GaAs substrate, it is advantageous for shortening the wavelength. A short-wavelength laser with an oscillation wavelength of 600 nm or less using such another material system has been proposed. For example, on a GaP substrate, _Al y _{Ga 1-y} P as a cladding layer (0 ≦ y ≦
1), using a direct transition type compressive strain Ga _x I as an active layer.
Japanese Patent Application Laid-Open No. 6-53602 proposes an element using n _1-x P (0 <x <1) and doping the active layer with N as an impurity of an isoelectronic trap. However, this structure has an advantage that the wavelength can be shortened by using a material having a small Al content in the active layer. However, the Ga _0.7 In _0.3 P active material which has a lattice constant closest to GaP and makes direct transition. The layer also has a 2.3% lattice mismatch with the GaP substrate, and the critical film thickness at which misfit dislocation due to the lattice mismatch does not occur becomes thin, which is not practically preferable.

Further, GaAs and GaP are formed on a GaAs substrate.
(AlGa) _a In _1-a P having a lattice constant between
Japanese Patent Application Laid-Open No. 5-41560 proposes an element for forming a double heterostructure composed of (0.51 <a ≦ 0.73) through a GaP _x As _1-x buffer layer lattice-matched thereto. I have. In this technique, the lattice mismatch between the substrate and the double heterostructure is eliminated by the buffer layer. FIG. 1 shows the relationship between the lattice constant and the band gap energy. In FIG. 1, the solid line is the material of the direct transition, and the broken line is the material of the indirect transition. (AlGa) _a In _1-a P having a lattice constant between GaAs and GaP (0.51 <a ≦
0.73) The system material is a material in a range surrounded by AlInP and GaInP. According to this technique, AlGaInP having a wider gap than the GaAs substrate lattice matching material can be used for the cladding layer and the active layer, which is advantageous for shortening the wavelength of a laser having a wavelength shorter than 600 nm. However, the laser proposed in JP-A-5-41560 has a structure for realizing a laser having a wavelength shorter than 600 nm, and has a structure of 635 nm and 650 nm.
The structure was not a structure considering a laser having a wavelength longer than 600 nm, such as a band. For example, the dependence of the band gap on the lattice constant is higher in GaInP than AlInP, which is an indirect transition material.
It can be seen that is larger in the range where the Ga composition which is a direct transition is up to 0.73. Since a wide gap material is suitable for the cladding layer, it is better to use Al (Ga) InP having a lattice constant close to that of GaP.
It becomes the material of the active layer in the 635 nm and 650 nm bands (A
1) The lattice constant of GaInP was largely deviated from that of the cladding layer, had a large compressive strain, and was insufficient, such as being undesirable.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a red semiconductor laser in the 635 nm or 650 nm band or the like which operates stably at a high temperature, a high output, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, and a visible light emitting device having a high luminous efficiency. It is intended to provide a semiconductor light emitting device such as a diode.

[0010]

[MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
According to the first aspect of the present invention, light is generated on a semiconductor substrate.
Having an active layer and a cladding layer for confining light
In a semiconductor light emitting device with a junction formed,
The layer is (Al_xGa_1-x)_αIn_1-αP_tAs
_1-t(0 ≦ x <1, 0 <α ≦ 1, 0 ≦ t ≦ 1)
The cladding layer has a larger band gap than the active layer and
including Al with a lattice constant between aP and GaAs
(Al_yGa_1-y)_βIn_1-βP_vAs_1-v (0 <
y ≦ 1, 0.5 <β <1, 0 <v ≦ 1)
Features.

According to a second aspect of the present invention, in a semiconductor light emitting device in which a heterojunction having an active layer for generating light and a cladding layer for confining light is formed on a semiconductor substrate, the active layer is formed of (Al _x Ga _1-x ) _α In _1-α P
_t As _1-t (0 ≦ x <1, 0 <α ≦ 1, 0 ≦ t ≦ 1) A single quantum well, the cladding layer has a larger band gap than the active layer, and the lattice between GaP and GaAs. (Al _y Ga _1-y ) _β In _1-β P containing Al having a constant
_v As _1−v (0 <y ≦ 1, 0.5 <β <1, 0 <v ≦
1), the band gap between the active layer and the cladding layer is larger than the active layer and smaller than the cladding layer (Al
_z Ga _1-z ) _γ In _{1-γ Pu} As _{1- u} (0 ≦ z <
1, 0.5 <γ <1, 0 <u ≦ 1).

According to a third aspect of the present invention, a semiconductor substrate is provided.
On top, an active layer that generates light and a cladding layer that confines light
Semiconductor light emitting device having a heterojunction having
, The active layer is a quantum well composed of a well layer and a barrier layer.
It has a well structure._x1Ga_1-x1)_α1
In_1-α1P_t1As_1-t1(0 ≦ x1 <1, 0 <
α1 ≦ 1, 0 ≦ t1 ≦ 1), and the barrier layer is made of (Al_x2
Ga_1-x2)_α2In_1-α2P_t2As_1-t2(0
≦ x2 <1, 0.5 <α2 <1, 0 ≦ t2 ≦ 1)
The cladding layer has a larger band gap than the active layer,
Including Al with a lattice constant between GaP and GaAs
(Al_yGa_1-y)_βIn_1-βP _vAs_1-v(0 <
y ≦ 1, 0.5 <β <1, 0 <v ≦ 1)
Band gap between the active layer and the cladding layer
Large and smaller than the cladding layer (Al_zGa_1-z)_γIn
_1-γP_uAs_1-u(0 ≦ z <1, 0.5 <γ <1,
0 <u ≦ 1).
It is a sign.

[0013] The invention according to claim 4 is based on claim 1.
The semiconductor light-emitting device according to claim 3.
And the active layer contains As (Al_xGa_1-x)_α
In _1-αP_tAs_1-t(0 ≦ x <1, 0 <α1 ≦
1, 0 ≦ t ≦ 1).

Further, an invention according to claim 5, in the semiconductor light emitting device according to any one of claims 2 to 4, the light guide layer contains no Al Ga γ In _1-γ P
_u As _1-u (0.5 <γ <1, 0 <u ≦ 1).

Further, an invention according to claim 6, wherein, in the semiconductor light emitting device according to any one of claims 1 to 5, the cladding layer contains As (Al _y Ga
_1-y ) _β In _{1−β Pv} As _1−v (0 <y ≦ 1, 0.
5 <β <1, 0 <v <1).

According to a seventh aspect of the present invention, in the semiconductor light emitting device according to any one of the second to sixth aspects, the well layer has a lattice constant larger than that of the cladding layer and has a compressive strain. It is characterized by having.

According to an eighth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to seventh aspects, the semiconductor substrate is made of GaPAs, and a heterojunction is formed on the semiconductor substrate. It is characterized by being grown.

According to a ninth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to seventh aspects, the semiconductor substrate is made of GaAs or GaP, and the semiconductor substrate and the cladding layer are disposed between the semiconductor substrate and the cladding layer. In addition, a heterojunction is crystal-grown via a buffer layer for relaxing lattice mismatch between the two.

The invention according to claim 10 is the invention according to claim 9.
The semiconductor light emitting device described above is characterized in that the relaxation buffer layer is formed of a graded layer whose lattice constant gradually changes in the growth direction from the lattice constant of the semiconductor substrate and approaches the lattice constant of the cladding layer.

The invention according to claim 11 is the same as the claim 9.
The semiconductor light emitting device described above is characterized in that the relaxation buffer layer has a strained superlattice structure in which at least two kinds of materials having different lattice constants are alternately stacked.

The invention according to claim 12 is the invention according to claim 9.
In the above described semiconductor light emitting device, the relaxation buffer layer comprises a low-temperature buffer layer grown at a temperature lower than the growth temperature of the cladding layer.

The thirteenth aspect of the present invention provides a ninth aspect.
13. The semiconductor light emitting device according to claim 12, wherein the relaxation buffer layer is made of GaInP or GaP.
It is characterized by being composed of As.

The invention according to claim 14 is the invention according to claim 8
10. The semiconductor light emitting device according to claim 9, wherein the plane orientation of the semiconductor substrate is a plane inclined from 0 ° to 54.7 ° in the [011] direction from the (100) plane, or a plane inclined from the (100) plane. It is characterized by a surface inclined in the range of 10 ° to 54.7 ° in the [0-11] direction or a surface equivalent thereto.

Further, the invention of claim 15 provides the invention of claim 8
10. The semiconductor light emitting device according to claim 9, wherein the surface of the GaPAs substrate is planarized by mechanical polishing prior to the crystal growth of the heterojunction, or the heterojunction is crystallized after the growth of the relaxation buffer layer. The surface before being grown is flattened by mechanical polishing.

Further, the invention of claim 16 provides the invention of claim 8
10. The semiconductor light emitting device according to claim 9, wherein an upper surface of an interface of the layer is a lower surface between the semiconductor substrate and the hetero junction.
It is characterized by including a layer that is flatter than (substrate side).

The invention according to claim 17 is the first invention.
6. In the semiconductor light-emitting device according to 6, in the layer in which the upper surface of the interface of the layer is flatter than the lower surface (substrate side), Se is 5 × 10 ¹⁸ c
It is characterized by being GaInP doped with m ^{- 3} or more.

The invention according to claim 18 is the same as the invention according to claim 9.
In the semiconductor light-emitting device described in the above, the relaxation buffer layer comprises S
GaInP doped with e to 5 × 10 ¹⁸ cm ⁻³ or more
It is characterized by being.

The invention according to claim 19 is the first invention.
19. The semiconductor light emitting device according to claim 18, wherein the heterojunction is grown by a metal organic chemical vapor deposition method or a molecular beam epitaxy method.

The invention according to claim 20 is the same as the claim 1.
9. The semiconductor light emitting device according to 9, wherein the buffer layer comprises:
It is characterized by being grown by metal organic chemical vapor deposition or molecular beam epitaxy.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing a configuration example of a semiconductor light emitting device according to the present invention. Referring to FIG. 2, in this semiconductor light emitting device, a heterojunction 4 having an active layer 2 for generating light and a cladding layer 3 for confining light is formed on a semiconductor substrate 1 of GaAs.

Here, in the first embodiment of the present invention,
Layer 2 is made of (Al_xGa_1-x)_αIn _1-αP_tAs
_1-t(0 ≦ x <1, 0 <α ≦ 1, 0 ≦ t ≦ 1)
The cladding layer 3 has a larger band gap than the active layer 2.
Al having a lattice constant between GaP and GaAs
(Al_yGa_1-y)_βIn_1-βP_vAs
_1-v(0 <y ≦ 1, 0.5 <β <1, 0 <v ≦ 1)
Has become.

In the first embodiment, the cladding layer 3
Contained an Al having a lattice constant between the GaP and _{GaAs (Al y Ga 1-y} ) β In 1-β P v As 1-v (0
<Y ≦ 1, 0.5 <β <1, 0 <v ≦ 1), and Ga
The band gap is larger than the cladding layer material that can be formed on the As semiconductor substrate 1, which is advantageous for shortening the wavelength. The active layer 2 _{(Al x Ga 1-x)} α In 1-α P t As 1-t
(0 ≦ x <1, 0 <α ≦ 1, 0 ≦ t ≦ 1),
The cladding layer 3 may have a strain, and the energy gap may be narrower (narrow gap) than the conventional material. For this reason, the range of element design is greatly expanded compared to the related art, and good characteristics can be obtained not only for a wavelength shorter than 600 nm but also for a light emitting element having a wavelength longer than 600 nm.

In the second embodiment of the present invention, FIG.
In the semiconductor light emitting device of (1), the active layer 2 is made of (Al _x Ga
_1−x ) _α In _{1−α Pt} As _1−t (0 ≦ x <1, 0 <
α ≦ 1, 0 ≦ t ≦ 1) A single quantum well, and the cladding layer 3 has a larger band gap than the active layer 2 and has GaP and G
aAs containing Al having a lattice constant between (Al _y
Ga _1-y ) _β In _{1-β Pv} As _1-v (0 <y ≦ 1,
0.5 <β <1, 0 <v ≦ 1), and between the active layer 2 and the cladding layer 3,
As shown in greater cladding layer 3 smaller than the active layer 2 is a bandgap _{(Al z Ga 1-z)} γ In 1-γ
_{P u As 1-u (0} ≦ z <1,0.5 <γ <1,0 <u
≦ 1) is provided.

[0034] In the second embodiment, the cladding layer 3 containing Al having a lattice constant between the GaP and _{GaAs (Al y Ga 1-y} ) β In 1-β P v As 1-v ( 0 <
y ≦ 1, 0.5 <β <1, 0 <v ≦ 1), and GaAs
The band gap is larger than the cladding layer material that can be formed on the s semiconductor substrate 1, which is advantageous for shortening the wavelength. In addition, (Al
_z Ga _1-z ) _γ In _{1-γ Pu} As _1-u (0 ≦ z <
1,0.5 <γ <1,0 <u ≦ 1) optical guiding layer 5 and made of _{(Al x Ga 1-x)} α In 1-α P t As
_{Since the} SCH structure is formed by the single quantum well active layer 2 composed of _1-t (0 ≦ x <1, 0 <α ≦ 1, 0 ≦ t ≦ 1), the Al content is smaller than that of the GaAs substrate lattice matching material. A wide gap can be obtained by the composition, the Al composition of the light guide layer 5 can be reduced as compared with the related art, and the luminous efficiency can be improved by reducing the non-radiative recombination current and the surface recombination current. In the case of a laser, the end face is hardly deteriorated, and stable operation can be performed even at a high output. In addition, the cladding layer 3 can be strained, and the energy gap can be narrowed (narrow gap) as compared with the conventional material. Further, in GaInP, when the Ga composition is reduced, the lattice constant increases and the band gap decreases. Sandip et al. (Appl. Ph.
ys. Lett. 60, 1992, pp 630-63
Referring to the estimation of the band discontinuity according to 2), the band gap changes on the conduction band side, and the energy on the valence band side hardly changes. That is, even if the composition is changed, the change in the energy of the valence band is small. on the other hand,
When Al is added to GaInP, the conduction band energy increases and the valence band energy decreases. The change is larger on the valence band side. Conventionally, in a structure on a GaAs substrate, it is necessary to use AlGaInP having a large Al composition for the light guide layer, and there is a large valence band discontinuity between the GaInP quantum well layer and the GaInP quantum well layer. That is, the band discontinuity on the conduction band side was not large enough. On the other hand, according to the second embodiment of the present invention, the light guide layer 5
Can reduce the Al composition, so that a large conduction band discontinuity can be obtained. As a result, carrier (electron) overflow due to small band discontinuity on the conduction band side, which has conventionally been a problem with red lasers made of AlGaInP-based materials, can be significantly improved. For this reason, since the width of the element design is greatly increased as compared with the related art, it is possible to obtain good characteristics not only in a light emitting element having a wavelength shorter than 600 nm but also in a light emitting element having a wavelength longer than 600 nm.

In the third embodiment of the present invention, FIG.
The active layer 2 of the heterojunction 4
Is a quantum well structure composed of a well layer and a barrier layer, and the well layer is ( _{Alx1Ga1 -x1} ) [ _{alpha] 1In1- [alpha] 1.}
P _t1 As _1-t1 (0 ≦ x1 <1, 0 <α1 ≦ 1, 0
≦ t1 ≦ 1 and the barrier layer is made of (Al _x2 G
_{a 1-x2) α2 In 1} -α2 P t2 As 1-t2 (0 ≦
x2 <1, 0.5 <α2 <1, 0 ≦ t2 ≦ 1), and the cladding layer 3 has a larger band gap than the active layer 2 and contains Al having a lattice constant between GaP and GaAs ( _{al y Ga 1-y) β} In 1-β P v As
_1-v (0 <y ≦ 1, 0.5 <β <1, 0 <v ≦ 1). In the heterojunction 4, between the active layer 2 and the cladding layer 3 is shown in FIG. Similarly, the band gap is larger than the active layer 2 and smaller than the cladding layer 3 (Al _z
Ga _1-z ) _γ In _{1-γ Pu} As _1-u (0 ≦ z <1,
There is provided a light guide layer 5 of 0.5 <γ <1, 0 <u ≦ 1).

In the third embodiment, the cladding layer 3
Contains Al having a lattice constant between GaP and GaAs.
(Al_yGa_1-y)_βIn_1-βP_vAs_1-v(0
<Y ≦ 1, 0.5 <β <1, 0 <v ≦ 1), and Ga
From the cladding layer material that can be formed on the As semiconductor substrate 1,
The gap is large, which is advantageous for shortening the wavelength. Also,
(Al_zGa_1-z)_γIn_1-γP_uAs_1-u(0 ≦
a light guide consisting of z <1, 0.5 <γ <1, 0 <u ≦ 1)
Layer 5 and (Al_x1Ga_1-x1)_α1In
_1-α1P_t1As_1-t1(0 ≦ x1 <1, 0 <α1
≦ 1, 0 ≦ t1 ≦ 1) and (Al_x2Ga
_1-x2)_α2In_1-α2P_t2As_1-t2(0 ≦ x
2 <1, 0 <α2 ≦ 1, 0 ≦ t2 ≦ 1)
To form an SCH structure.
The Al composition of the guide layer 5 can be reduced, and the non-radiative recombination current can be reduced.
Improved luminous efficiency by reducing the surface recombination current
In the case of a laser, the end face is hardly deteriorated.
Thus, stable operation is possible even at high output. Also clad
The well layer may have a strain with respect to the layer 3 and the barrier layer
The direction of strain of the well layer is
Good quantum well structure can be obtained by compensating for distortion.
You. In addition, by using a multiple quantum well structure, sufficient carriers can be obtained.
It becomes possible to confine it to the well layer. In addition,
Make the energy gap narrower than the material (narrow gap
). Further, GaInP is Ga
Decreasing the composition increases the lattice constant and
The gap becomes smaller. Sandip et al. (App
l. Phys. Lett. 60, 1992, pp630
~ 632) to estimate the band discontinuity
Change in the band gap occurs on the conduction band side and the valence band
The energy on the side has hardly changed. In other words,
Even if the composition is changed, the change in valence band energy is small. one
On the other hand, when Al is added to GaInP, the conduction band energy
Increases and the valence band energy decreases. That strange
The conversion is larger on the valence band side. Conventionally, on a GaAs substrate
In the structure, AlGaInP with a large Al composition is used for the light guide layer.
And a large gap between the GaInP quantum well layer
It had band discontinuity on the valence band side. In other words, conduction
The band discontinuity on the band side was not large enough. this
On the other hand, according to the third embodiment of the present invention, the light guide layer
5 can be reduced, so that a large conduction band
A continuity is obtained. Thereby, the conventional AlGaInP-based material
Band in the conduction band which was a problem with the red laser
Carrier (electron) overflow due to small continuity
The temperature characteristics can be improved at a low threshold
there were. For this reason, the width of element design is wider and wider than before.
Therefore, not only wavelengths shorter than 600 nm but also 600 n
good characteristics even for light emitting elements with wavelengths longer than
Can be

In the fourth embodiment of the present invention, in the semiconductor light emitting device of the first, second or third embodiment, the active layer 2 contains As (Al _x Ga).
_1−x ) _α In _{1−α Pt} As _1−t (0 ≦ x <1, 0 <
α1 ≦ 1, 0 ≦ t ≦ 1).

In the fourth embodiment, the addition of As decreases the band gap. Therefore, even when the cladding layer 3 having a large band gap close to GaP is used, the band gap is lower than 600 nm in the 635 nm and 650 nm bands. Applicable to long wavelength devices. That is, the conventional GaAs
The clad layer 3 has a larger band gap than the 635 nm and 650 nm band devices on the semiconductor substrate, so that carrier overflow is reduced and good device characteristics such as stable operation at high temperatures can be obtained.

In the fifth embodiment of the present invention,
In the semiconductor light emitting device of the second, third or fourth embodiment,
The light guide layer 5 is made of Ga that does not contain Al._γIn
_1-γP _uAs_1-u(0.5 <γ <1, 0 <u ≦ 1)
It has become.

In the fifth embodiment, the lattice constant is GaAs.
When s is smaller than s, the band gap increases, and attention has been paid to the fact that the Al composition can be reduced in order to obtain a material having the same band gap. According to the fifth embodiment, the light The Al composition of the guide layer 5 can be reduced. For example, the red laser on a GaAs semiconductor substrate 1, typically a band gap wavelength of about 570nm is _{(Al 0.5 Ga 0 .5) 0.5} In 0.5 P is used, the fifth embodiment According to the material having a lattice constant between GaP and GaAs, Ga containing no Al
_0.7 In _{0 .} This band gap wavelength is achieved by ₃ P. Therefore, even in a red laser having a wavelength of 635 nm or 650 nm or the like, the active region can be formed of a material containing no Al, and the non-radiative recombination current and the surface recombination current caused by Al can be reduced, thereby improving the luminous efficiency. The end face is hardly deteriorated, and stable operation is possible even at high output.

According to the sixth embodiment of the present invention, in the semiconductor light emitting device of the first, second, third, fourth or fifth embodiment, the cladding layer contains As (A
_{l y Ga 1-y) β} In 1-β P v As 1-v (0 <y ≦
1, 0.5 <β <1, 0 <v <1).

[0042] (100) plane and (100) slope from the small GaP, MOCV GaAs, the GaP _0.4 As _{0 .6} substrate
When AlGaInP was grown by the D method or the like, many hill-shaped defects called hillocks were observed on the growth surface. This is A
This was particularly noticeable when the Al composition such as lInP was large. If a large number of hillocks are present in the growth layer, the characteristics of devices such as lasers and LEDs are deteriorated, and the yield is lowered, which is not preferable in production. Al during growth
Alternatively, Ga forms droplets, which serve as nuclei to form hillocks. The inventors of the present application provide AlGa
It has been found that the inclusion of As during the growth of InP can dramatically reduce the hillock density. In FIGS. 11A and 11B,
GaP 2 ° off from (100) plane in [110] direction
AlInP on _0.4 As _0.6 epi-substrate (Fig. 11 (a)) and A
A surface Nomarski (surface morphology) photograph of 1InPAs (FIG. 11B) is shown. Here, A in FIG.
lInP and AlInPAs in FIG.
Grown at ℃. The As composition of AlInPAs was about 10%. The hillocks also depended on the growth conditions, and the hillock density could be reduced by raising the growth temperature of AlInP from 700 ° C. to 750 ° C., but there are still many hillocks as shown in FIG. However, by adding As, FIG.
As shown in (b), the hillock density could be drastically reduced. Even when the growth temperature was lowered to 700 ° C., the hillock density also decreased dramatically. This is presumably because the formation of Al or Ga droplets is suppressed. The effect was small even with a small As composition, and the higher the As composition, the greater the effect of reducing the hillock density. Due to the hillock reduction effect of As addition, deterioration of device characteristics and reduction in yield can be suppressed.

According to the seventh embodiment of the present invention, in the semiconductor light emitting device of the second, third, fourth, fifth or sixth embodiment, the lattice constant of the well layer is larger than that of the cladding layer. , And has a compression strain.

In the conventional 635 nm band laser on a GaAs substrate, a material having a small band gap (mainly GaInP) is formed in a compression strain well layer, the well width becomes too narrow, and the influence of the interface becomes large, resulting in good performance. Since it is difficult to obtain, a tensile strain well layer is used. For this reason, the polarization was in the TM mode. On the other hand, in the sixth embodiment of the present invention, the band gap is increased, so that a quantum well layer having an optimal thickness can be formed even if a material having a larger lattice constant than the cladding layer 3 is used for the well layer. A high-performance 635 nm band laser structure with a compression strain can be easily obtained. In addition, the presence of the compressive strain causes the polarized light to be in the TE mode, becomes the same as a laser in a general other wavelength band, and can be used without changing the optical system, which is convenient for application.

According to the eighth embodiment of the present invention, in the semiconductor light emitting device of the first, second, third, fourth, fifth, sixth or seventh embodiment, the semiconductor substrate 1 is made of GaPA.
The heterojunction 4 is crystal-grown on the semiconductor substrate 1.

In the eighth embodiment, GaP and GaAs are used.
GaPAs, which has a lattice constant between GaAs and s, is grown thickly (for example, to a thickness of 30 μm) on a GaP or GaAs substrate 1, and a material that can be substantially regarded as a GaPAs substrate is VPE.
It can be grown by a (vapor phase growth) method or the like. By making the uppermost portion the same as the lattice constant of the heterojunction 4 (at least the cladding layer 3), the present material system can be grown without lattice irregularity.

According to the ninth embodiment of the present invention, in the semiconductor light emitting device of the first, second, third, fourth, fifth, sixth or seventh embodiment, the semiconductor substrate 1 is made of GaAs.
Alternatively, as shown in FIG. 4, the heterojunction 4 is crystal-grown between the semiconductor substrate 1 and the cladding layer 3 via the buffer layer 6 for relaxing lattice mismatch between the two.

In the ninth embodiment, a buffer layer 6 for reducing lattice mismatch is formed on a GaAs or GaP substrate 1.
By forming the heterojunction 4 through the interface, the lattice mismatch can be reduced and the heterojunction 4 can be grown. In addition, the same crystal growth apparatus can be used for continuous and continuous growth, and only one apparatus is required.

In the semiconductor light emitting device of the ninth embodiment, the relaxation buffer layer 6 has a lattice constant whose lattice constant gradually changes from the lattice constant of the semiconductor substrate 1 in the growth direction and approaches the lattice constant of the cladding layer 3. Can be configured as a dead layer.

As described above, when a graded layer is used as the relaxation buffer layer 6, since lattice relaxation occurs gradually, threading dislocations can be prevented from growing above the graded layer, and the heterojunction can be prevented. The crystallinity of No. 4 need not be reduced.

In the semiconductor light emitting device according to the ninth embodiment, the relaxation buffer layer 6 may have a strained superlattice structure in which at least two kinds of materials having different lattice constants are alternately stacked.

As described above, when a strained superlattice structure is used as the relaxation buffer layer 6, crystal defects caused by lattice relaxation can be confined within the strained superlattice structure, and the crystallinity of the heterojunction 4 is degraded. Can be prevented.

In the semiconductor light emitting device of the ninth embodiment, the buffer layer 6 can be configured as a low-temperature buffer layer grown at a temperature lower than the growth temperature of the cladding layer 3.

As described above, when the low-temperature buffer layer is used as the relaxation buffer layer 6, crystal defects caused by lattice relaxation can be confined in the low-temperature buffer layer, and a decrease in the crystallinity of the hetero junction 4 can be prevented. be able to.

In each of the above examples, GaInP or GaPAs can be used for the relaxation buffer layer 6.

GaPAs or GaInP is a ternary material and can be easily controlled. When using GaPAs, it is only necessary to add As to GaP when the semiconductor substrate 1 is a GaP substrate, and Ga is used when the semiconductor substrate 1 is a GaAs substrate.
It is only necessary to add P to As, and control is easy. G
In the case of aInP, P is the only V group with a high vapor pressure,
In particular, the interface can be easily controlled when growing a strained superlattice structure.

In the semiconductor light emitting device of the eighth or ninth embodiment, the plane orientation of the semiconductor substrate 1 is (1
A plane inclined in the range of 0 ° to 54.7 ° from the (00) plane in the [011] direction, or a plane inclined in a range of 10 ° to 54.7 ° in the [0-11] direction from the (100) plane. Or an equivalent plane.

That is, the plane orientation of the semiconductor substrate 1 is set to (1
(00) plane in the range of 0 ° to 54.7 ° in the [011] direction, or (100) plane in the range of 10 ° to 54.7 ° in the [0-11] direction. The formation of a natural superlattice can be suppressed by
As compared with the case where a natural superlattice is formed, a wide gap is formed at the same composition ratio, which is advantageous for shortening the wavelength. In addition, an end face type laser usually uses a cleavage plane for a resonator. If the plane orientation of the substrate 1 is inclined in the above direction, the cleavage plane in the direction perpendicular to the inclination direction is not perpendicular, but if it is cleaved in the inclined direction, a vertical plane is obtained and a laser resonator can be formed. It is not preferable to incline in the direction other than the above direction, since the cleavage plane does not become vertical. The hillock density can be reduced by inclining the plane orientation of the substrate from the (100) plane. As a result, it is possible to suppress the deterioration of the device characteristics and the yield.

In the semiconductor light emitting device according to the eighth or ninth embodiment, the surface of the GaPAs substrate is flattened by mechanical polishing before growth of the heterojunction, or growth of the buffer layer is performed. The surface afterwards and before the crystal growth of the heterojunction is preferably planarized by mechanical polishing.

On the surface of the GaPAs substrate 1 or on the surface after the growth of the buffer layer 6, cross-hatched irregularities related to lattice irregularity are usually formed. These irregularities can be a source of generation of new crystal defects when the heterojunction 4 is grown thereon. This can be prevented by flattening by polishing and growing the heterojunction 4 thereon.

Further, in the semiconductor light emitting device of the eighth or ninth embodiment, the semiconductor substrate 1 and the hetero junction 4
And a layer in which the upper surface of the interface of the layer is flatter than the lower surface (substrate side).

That is, on the surface of the GaPAs substrate 1 or the surface after the growth of the relaxation buffer layer 6, cross-hatched irregularities related to lattice irregularity are usually formed. These irregularities can be the origin of the generation of new crystal defects when the heterojunction 4 is grown thereon. When a layer that grows by embedding such irregularities is included, the upper layer becomes flat, which can be prevented.

In this case, the upper surface of the interface between the layers is the lower surface.
The layer that is flatter than the (substrate side) has Se of 5 × 10 ¹⁸ cm.
GaInP doped to ^-3 or more can be used.

That is, the inventor of the present application has found that GaInP doped with Se at a high concentration has a property of growing by embedding irregularities. As a result, the upper surface of the interface of the layer becomes flatter than the lower surface (substrate side), so that it is possible to prevent the generation of new crystal defects originating from the irregularities when the heterojunction 4 is grown.

In the semiconductor light emitting device according to the ninth embodiment, the relaxation buffer layer 6 has a thickness of 5 × 10 ¹⁸ cm.
GaInP doped to ^-3 or more is preferable.

That is, Se has the property of growing by embedding the irregularities in the relaxation buffer layer 6 itself, which is the origin of generating cross-hatch irregularities related to lattice irregularities.
By using GaInP doped with a high concentration of, the effect of alleviating lattice irregularity and the effect of flattening the surface can be obtained, and the total thickness of the grown layer can be reduced.

In each of the semiconductor light emitting devices of the above-described examples, the heterojunction 4 is formed by metal organic chemical vapor deposition (MOC).
It can be grown by VD) or molecular beam epitaxy (MBE).

That is, the AlGaInP (As) -based material has a large segregation coefficient of Al from a solution to a solid phase, and it is difficult to grow a liquid layer from the viewpoint of controlling the composition. In addition, vapor phase epitaxy (VPE) by the halogen transport method uses the raw material AlCl
However, it is difficult to corrode the quartz reaction tube. on the other hand,
Metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) are highly non-equilibrium growth methods.
Since growth is governed by the group III raw material supply rule, these materials are extremely effective for growth and can be easily grown.

The relaxation buffer layer 6 can also be grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

In this case, continuous growth can be performed with the same device as the crystal growth device for the heterojunction, and only one device is required.

[0071]

Embodiments of the present invention will be described below. In the following Examples 1 to 7, the basic configuration of the semiconductor light emitting device (semiconductor laser device) is as shown in FIG. That is, although the material, composition, and the like are different for each embodiment, the basic configuration of each embodiment is as shown in FIG. Therefore, in Examples 1 to 7, for convenience, the semiconductor light emitting devices of Examples 1 to 7 will be described as having the basic configuration of FIG. FIG.
Has a SCH-SQW structure as a layer structure.

Example 1 In Example 1, first, the Ga composition was gradually changed from 0.5 to 0.7 by MOCVD on the GaAs substrate 11 turned off by 15 ° in the [011] direction from the (100) plane. Then, an n-GaInP graded buffer layer 12 having a thickness of 2 μm and doped with Se to 5 × 10 ¹⁸ cm ⁻³ or more is laminated, and Se is formed thereon as a surface flattening layer.
N-Ga _0.7 In doped to ¹⁸ cm ⁻³ or more
A composition uniform layer 13 made of _0.3 P and having a thickness of 1 μm is grown to reduce lattice mismatch. By doping Se, cross hatch-like irregularities due to lattice relaxation were reduced. Experiments have shown that Se is highly concentrated (5 × 10 ¹⁸ cm ³
(Preferably the above) GaInP doped has the property of growing by embedding irregularities. That is, the upper surface of the interface of the Se-doped n-Ga _0.7 In _0.3 P composition uniform layer 13 was flatter than the lower surface (substrate side). When growing a heterojunction on an uneven surface,
A new crystal defect originating from the unevenness was generated, but this could be prevented by flattening. Since Se was added at a high concentration to the graded layer, the surface flattening effect was obtained, and the surface flattening layer could be thinned.

Next, the lattice constant between GaP and GaAs
And Ga_0.7In_0.3N equal to the lattice constant of P
− (Al_yGa_1-y)_βIn_1-βP_vAs_1-v(Y
= 1, β = 0.7, v = 1) cladding layer 14 (film thickness 1
μm), (Al_zGa_1-z) _γIn_1-γP_uAs
_1-u(z = 0.1, γ = 0.7, u = 1) Light guide layer 1
5 (thickness: 0.1 μm) and compressive strain (Al_xGa
_1-x)_αIn_1-αP_tAs_1-t(x = 0, α = 0.
6, t = 1) single quantum well active layer 16 (film thickness 8n
m), (Al_zGa_1-z)_γIn_1-γP_uAs_1-u
(z = 0.1, γ = 0.7, u = 1) Light guide layer 17 (film
Thickness is 0.1 μm), p- (Al_yGa_1-y)_βIn
_1-βP_vAs_1-v(y = 1, β = 0.7, v = 1)
Lad layer 18 (1 μm thick), p-Ga_0.7In
_0.3P cap layer 19 (thickness: 0.1 μm), p-G
forming an aAs contact layer 20 (having a thickness of 0.005 μm);
Lengthened. Here, the cladding layers 14, 18 and the guide
The layers 15, 17 are made of Ga_0.7In_0.3P composition uniform layer 1
3 is lattice-matched.

On the contact layer 20, SiO ₂ as an insulating film 21 and a p-side electrode 22 are formed, and on the back surface of the substrate 11, an n-side electrode 23 is formed. Although this semiconductor light emitting device is configured as an insulating film stripe structure, other structures can be used.

In the first embodiment, the cladding layers 14 and 18
In addition, the light guide layers 15 and 17 have a wider gap than a material system lattice-matched to a conventional GaAs substrate, and a semiconductor laser oscillating at a wavelength of 595 nm shorter than 600 nm can be obtained by this structure. In spite of the wavelength shorter than 600 nm, the Al composition could be reduced as compared with the conventional light guide layer used for a 635 nm band laser on a GaAs substrate. Therefore, the non-radiative recombination current caused by Al was reduced, and the luminous efficiency was improved. In addition, the surface recombination current was reduced, the level of end face light degradation was increased, and a high output was obtained. Further, in the first embodiment, GaInP is used for the quantum well active layer 16. In GaInP, when the Ga composition is reduced, the lattice constant increases and the band gap decreases. Sandip et al. (Appl. Phys. Lett.
60, 1992, pp. 630-632), the band gap changes mainly on the conduction band side, and the energy on the valence band side hardly changes. That is, even if the composition is changed, the change in the energy of the valence band is small. On the other hand, A to GaInP
When l is added, the conduction band energy increases and the valence band energy decreases. The change is larger on the valence band side. Conventionally, in a structure on a GaAs substrate, it is necessary to use AlGaInP having a large Al composition for the light guide layer, and there is a large valence band discontinuity between the GaInP quantum well layer and the GaInP quantum well layer. That is, the band on the conduction band side was not large enough. According to the present invention, since the Al composition of the light guide layers 15 and 17 can be reduced, a large conduction band discontinuity can be obtained. Thereby, the conventional AlG
The carrier (electron) overflow due to the small band discontinuity on the conduction band side, which was a problem in the red laser using the aInP-based material, could be significantly improved, and the temperature characteristics were good at a low threshold.

In the first embodiment, the cladding layer 1
The compositions of 4, 18 have a band gap larger than that of the active layer 16 and contain (Al _y Ga _1-y ) _β In _1-β containing Al.
_{P v As 1-v (0} <y ≦ 1,0.5 <β <1,0 <v ≦
1) can be used. The light guide layers 15 and 17
The band gap is smaller than the cladding layers 14 and 18 and is larger than the active layer 16, and the lattice constant is higher than the cladding layers 14 and 18.
It is the same as _{(Al z Ga 1-z)} γ In 1-γ P u As
_1-u (0 ≦ z <1, 0.5 <γ <1, 0 <u ≦ 1) can be used. In the first embodiment, the active layer 16
Used a single quantum well active layer, but may use multiple quantum wells. Although the lattice constant changes depending on the value of β of the cladding layers 14 and 18, it can be dealt with by changing the lattice constant of the uppermost surface of the relaxation buffer layers (12 and 13) to be the same as the cladding layers 14 and 18.

The plane orientation of the GaAs substrate is (10
0) A range of 0 ° to 54.7 ° in the [011] direction from the plane, or 10 ° in the [011] direction from the (100) plane.
When it is tilted within a range of 54.7 ° from the range, formation of a natural superlattice can be suppressed, and a decrease in band gap can be prevented, which is advantageous for shortening the wavelength. In addition, an end face type laser usually uses a cleavage plane for a resonator. If the plane orientation of the substrate 11 is inclined in the above direction, the cleavage plane in the direction perpendicular to the inclination direction is not perpendicular, but if the cleavage is performed in the inclined direction, a vertical plane is obtained and a laser resonator can be formed. It is not preferable to incline in the direction other than the above direction, since the cleavage plane does not become vertical.
Further, by inclining the plane orientation of the substrate from the (100) plane, the hillock density can be reduced, thereby suppressing the deterioration of device characteristics and the decrease in yield. In the first embodiment, the lattice relaxation buffer layers 12 and 13 and the heterojunction are grown once by the MOCVD method, and only one device is required. The structure shown in FIG. 5 can also be grown by MBE (molecular beam epitaxy). A heterojunction AlGaInP (A
s) The material has a large segregation coefficient of Al from a solution to a solid phase, and it is difficult to grow a liquid layer from the viewpoint of composition control. In addition, the vapor phase epitaxy (VPE) by the halogen transport method uses Al as a raw material.
It is difficult because Cl corrodes the quartz reaction tube. On the other hand, metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) are highly non-equilibrium growth methods, and the growth is governed by the group III raw material supply rule. Is extremely effective and can grow easily. In the first embodiment, the semiconductor laser has been described.
Also applicable to light emitting diodes.

Embodiment 2 In Embodiment 2, 635n of a quantum well active layer containing As is used.
This is an example of application to a red laser of m, 650 nm or the like. That is, in Example 2, the quantum well active layer has As
It is included. In the second embodiment, first, the Ga composition is changed from 0.5 to 0.7 by MOCVD on the GaAs substrate 11 turned off by 15 ° in the [011] direction from the (100) plane.
The n-GaInP graded buffer layer 12 having a film thickness of 2 μm doped with Se to 5 × 10 ¹⁸ cm ⁻³ or more is laminated thereon, and Se is deposited thereon at 5 × 10 ¹⁸ cm ^−3.
N-Ga _0.7 In doped to ¹⁸ cm ⁻³ or more
A composition uniform layer 13 made of _0.3 P and having a thickness of 1 μm is grown to reduce lattice mismatch. By doping Se at a high concentration, cross-hatch irregularities due to lattice relaxation were reduced. That is, n-Ga _0.7 I doped with Se
The upper surface of the interface of the n _0.3 P composition uniform layer 13 was flatter than the lower surface (substrate side). As a result, it is possible to prevent the generation of new crystal defects originating from the irregularities when the heterojunction is grown.

Next, n is a lattice constant between GaP and GaAs which is equal to the lattice constant of Ga _0.7 In _0.3 P.
_{- (Al y Ga 1-y} ) β In 1-β P v As 1-v (y =
0.7, β = 0.7, v = 1) cladding layer 14 (film thickness 1 μm), (Al _z Ga _1-z ) _γ In _{1-γ Pu} As
_1-u (z = 0.1, γ = 0.7, u = 1) Light guide layer 1
(Al _x Ga _{1 -x} ) _α In _{1 -α Pt} As _{1 -t} (x
= 0, α = 0.6, t = 0.9) Single quantum well active layer 1
6 (thickness _{8nm), (Al z Ga 1} -z) γ In 1-γ
_{P u As 1-u (z} = 0.1, γ = 0.7, u = 1) optical guiding layer 17 (thickness 0.1μm), p- _(Al y Ga
_1-y ) _β In _{1−β Pv} As _1−v (y = 0.7, β =
0.7, v = 1) cladding layer 18 (film thickness 1 μm), p
-Ga _0.7 In _0.3 P cap layer 19 (having a thickness of 0.
1 μm), p-GaAs contact layer 20 (having a thickness of 0.1 μm).
005 μm). The cladding layers 14 and 18 and the light guide layers 15 and 17 are formed of Ga _. Lattice-matched to ₇ In _0.3 P.

On the contact layer 20, SiO ₂ as an insulating film 21 and a p-side electrode 22 are formed, and on the back surface of the substrate 11, an n-side electrode 23 is formed. Although this semiconductor light emitting device is configured as an insulating film stripe structure, other structures can be used.

In the lattice constant of the cladding layers 14 and 18 of the second embodiment, even if GaInP having a small band gap is used out of AlGaInP, a strain of 1% is required to obtain 635 nm.
Well, and the crystallinity is reduced.
6 was added with As to adjust the band gap. Of course, As may not be added if the structure (composition) can obtain a required wavelength.

With the structure of Example 2, a semiconductor laser oscillating at a wavelength of 635 nm was obtained. Since the compression-strain quantum well active layer 16 was used, the polarization was in the TE mode. Most of the lasers in other wavelength bands are in TE mode, which is convenient for application. Of course, if the well layer is a material of direct transition, a tensile strain quantum well active layer may be used. In order to use a tensile strained quantum well layer which is a direct transition, it is desirable that the lattice constant of the cladding layer be larger than that of the second embodiment. The cladding layers 14 and 18 and the optical guide layers 15 and 17 have a wider gap than a conventional material system lattice-matched to a GaAs substrate, and the band discontinuity is increased. As a result, carrier confinement is improved. In addition to the effect of the compressive strain and the effect of the quantum well, a wide-gap material can be used as the compressive strain quantum well layer. Therefore, the conventional compressive strain quantum well layer using a cladding layer having a lattice constant to a GaAs substrate. The width of the well is thicker than
The adverse effects of the interface have been reduced. Further, the Al composition of the light guide layer, which is made into Group III, is 0.07, which can be reduced as compared with the conventional case, the non-radiative recombination current caused by Al is reduced, and the luminous efficiency is improved. In addition, the surface recombination current is reduced, the level of end face light degradation is improved, and a high output is obtained.

The composition of the cladding layers 14 and 18 has a larger band gap than the active layer 16 and contains Al.
_{(Al y Ga 1-y)} β In 1-β P v As 1-v (0 <
y ≦ 1, 0.5 <β <1, 0 <v ≦ 1) can be used. Further, the optical guide layers 15 and 17 have a band gap smaller than that of the cladding layers 14 and 18, larger than that of the active layer 16, and have the same lattice constant as that of the cladding layer (Al _z Ga).
_1−z ) _γ In _{1−γ Pu} As _1−u (0 ≦ z <1, 0.
5 <γ <1, 0 <u ≦ 1) can be used. In the second embodiment, a single quantum well active layer is used, but a multiple quantum well may be used. Further, β of the cladding layers 14 and 18
Can be dealt with by changing the lattice constant of the uppermost surface of the lattice relaxation buffer layer to be the same as that of the cladding layers 14 and 18.

Further, as in the second embodiment, the GaAs substrate 1
The plane orientation of 1 ranges from 0 ° to 54.7 ° in the [011] direction from the (100) plane or [011] from the (100) plane.
When it is tilted in the range of 10 ° to 54.7 ° in the [1] direction, formation of a natural superlattice can be suppressed, so that a decrease in band gap can be prevented, which is advantageous for shortening the wavelength. Further, in the above example, the lattice relaxation buffer layers 12 and 13 and the hetero junction are grown by MOCVD, but they can also be grown by MBE (molecular beam epitaxy).

Embodiment 3 Embodiment 3 is different from Embodiment 2 in the material of the lattice buffer layer 12. That is, in the third embodiment, (10
0) GaAs turned off by 15 ° in [011] direction from plane
The P composition was gradually changed from 0 to 0.4 on the substrate 11 by MOCVD, and the Se-doped film thickness was 2
μm n-GaPAs graded lattice buffer layer 12 is laminated, and Se-doped n-GaP
_0.4 As _{0. 6} is a uniform composition layer 1 having a thickness of 1 μm.
3 was grown to reduce lattice mismatch. That is, in the first and second embodiments, GaInP is used for the lattice relaxation buffer layer, but in the third embodiment, GaPAs is used for the lattice relaxation buffer layer. Others are the same as the second embodiment. In the third embodiment, the same effect as in the second embodiment was obtained.

Embodiment 4 Embodiment 4 is different from Embodiment 2 in that a lattice buffer layer is provided.
This is the structure of No. 12. That is, in the fourth embodiment, (100)
Substrate 1 turned off by 15 ° in the [011] direction from the surface
As shown in FIG.
Ga lattice-matched to the As substrate 11_0.5In_0.5P and
Ga which is the same as the lattice constant of the cladding layer 14_0.7In
_0.3Se composed of P is 5 × 10¹⁸cm^-3more than
A 2 μm-thick lattice buffer consisting of a doped n-strain superlattice
Buffer layer (n-GaInP / GaInP superlattice buffer
A), and Se is 5 × 10¹⁸c
m ^-3N-Ga doped above_0.7In_0.3P
The composition uniform layer 13 of 1 μm consisting of
Relaxed. Others are the same as the second embodiment. Example 4
However, the same effect as in Example 2 was obtained.

Embodiment 5 Embodiment 5 differs from Embodiment 2 in the structure of the lattice buffer layer 12. That is, in the fifth embodiment, (100)
Substrate 1 turned off by 15 ° in the [011] direction from the surface
On n-type semiconductor layer 1, an n-type semiconductor layer grown at a lower temperature than cladding layer 14 made of GaP _0.4 As _0.6 having the same lattice constant as cladding layer 14 by MOCVD at a lower temperature than 0.1 μm.
Low lattice relaxation buffer layer (n-GaPAs temperature buffer layer) 12 was laminated, thereon Se to 5 × ¹⁰ 18 cm
^A 2 μm-thick compositionally uniform layer 13 of n-Ga _0.7 In _0.3 P doped at ⁻³ or more was grown to reduce lattice mismatch. Others are the same as the second embodiment. Example 5
The same effect as in Example 2 was obtained in

Embodiment 6 Embodiment 6 uses 635n with a light guide layer containing no Al.
This is an example of application to a red laser of m, 650 nm or the like. In the sixth embodiment, the Ga composition is gradually changed from 0.5 to 0.7 by MOCVD on the GaAs substrate 11 which is turned off by 15 ° in the [011] direction from the (100) plane, and Se is changed to 5 ×. N-GaInP graded buffer layer 12 doped to 10 ¹⁸ cm ⁻³ or more and having a thickness of 2 μm
And a 1 μm-thick compositionally uniform layer 13 of n-Ga _0.7 In _0.3 P doped with Se at 5 × 10 ¹⁸ cm ⁻³ or more is grown thereon. Relax. By doping Se at a high concentration, cross-hatched irregularities due to lattice relaxation were reduced. That is, S
The upper surface of the interface of the e-doped n-Ga _0.7 In _0.3 P composition uniform layer 13 was flatter than the lower surface (substrate side). As a result, it is possible to prevent the occurrence of new crystal defects originating from the irregularities when the heterojunction is grown.

Next, the lattice constant between GaP and GaAs
And Ga_0.7In_0.3N equal to the lattice constant of P
− (Al_yGa_1-y)_βIn_1-βP_vAs_1-v(y =
0.7, β = 0.7, v = 1) cladding layer 14 (film thickness 1
μm), not containing Al (Al _zGa_1-z)_γIn
_1-γP_uAs_1-u(z = 0, γ = 0.7, u = 1) light
Guide layer 15 (0.1 μm thick), FIG. 7 shows its structure
It has a compressive strain (Al_xGa_1-x)_αIn
_1-αP_tAs_1-t(x = 0, α = 1, t = 0.3)
Door layer (8 nm thick) and not containing Al (Al_zGa
_1-z)_γIn_1-γP_uAs_1-u(z = 0, γ = 0.
7, u = 1) 3 layers of barrier layers (thickness: 10 nm) alternately
The layered multiple quantum well active layer 16, which does not contain Al (A
l_zGa_1-z)_γIn _1-γP_uAs_1-u(z = 0,
γ = 0.7, u = 1) Light guide layer 17 (film thickness 0.1 μm)
m), p- (Al_yGa_1-y)_βIn_1-βP_vAs
_1-v(y = 0.7, β = 0.7, v = 1) Cladding layer 1
8 (film thickness 1 μm), p-Ga_0.7In_{0. 3}P cap
Layer 19 (0.1 μm thickness), p-GaAs contact
A layer 20 (with a thickness of 0.005 μm) is grown. Cladding layer
The light guide layers 15, 17 and the light guide layers 15, 17 are Ga_0.7I
n_0.3It is lattice-matched to P.

On the contact layer 20, SiO ₂ as the insulating film 21 and the p-side electrode 22 are formed, and on the back surface of the substrate 11, an n-side electrode 23 is formed. Although this semiconductor light emitting device is configured as an insulating film stripe structure, other structures can be used.

In the cladding layers 14 and 18 of the sixth embodiment, even if GaInP having a small band gap is used among AlGaInP, strain must be increased to obtain 650 nm, and crystallinity is deteriorated. Therefore, As was added to the well layer 16 to adjust the band gap.
Also, for GaInP, when the Ga composition is reduced, the lattice constant increases and the band gap decreases. Sand
Referring to the estimation of band discontinuity by ip et al. (Appl. Phys. Lett. 60, 1992, pp. 630-632), the band gap changes on the conduction band side, and the energy on the valence band hardly changes . That is, when a heterojunction between an Al-free wide-gap GaInP optical guide layer and a compressively-strained GaInP quantum well layer having a larger lattice constant is formed,
The band discontinuity is almost only on the conduction band side. This allows
Carrier due to small band discontinuity on the conduction band side, which has been a problem with red lasers using conventional AlGaInP-based materials
(Electronic) overflow can be significantly improved.
However, on the contrary, there is a concern that the confinement of holes on the valence band side becomes worse. Here, when As is added to GaInP, the band gap becomes smaller. However, since the change in the valence band side is larger, there is an effect that a structure capable of sufficiently confining holes can be realized.

With the structure of Example 6, a semiconductor laser oscillating at a wavelength of 650 nm was obtained. The polarization was in TE mode. The cladding layers 14 and 18 and the light guide layer 15
17 has a wider gap and a larger band discontinuity than a conventional material system lattice-matched to a GaAs substrate,
Carrier confinement has improved. Further, in the sixth embodiment, since the multi quantum well structure is employed, carriers can be more sufficiently confined in the well layer. In addition to the compressive strain effect and the quantum well effect, a wide gap material can be used as the compressive strain quantum well layer.
The well width was larger than that of a conventional compressive strain well layer using a cladding layer lattice-matched to a GaAs substrate, and the adverse effect of the interface was reduced. Further, since the light guide layers 15, 17 and the well layer 16 have a structure containing no Al, the non-radiative recombination current caused by Al is reduced, and the luminous efficiency is improved. In addition, the surface recombination current was reduced, the level of end face light degradation was remarkably improved, and a high output was obtained.
As a result, a red laser that operates stably at high temperature and high output was obtained.

The composition of the cladding layers 14 and 18 is determined according to the active layer 1
The band gap was larger than that of No. 6 and contained Al (Al _y G
a _1-y ) _β In _{1−β Pv} As _1−v (0 <y ≦ 1,
0.5 <β <1, 0 <v ≦ 1) can be used.
Although the lattice constant changes depending on the value of β of the cladding layers 14 and 18, it can be dealt with by changing the lattice constant of the uppermost surface of the lattice relaxation buffer layer 12 to be the same as that of the cladding layer 14. In Example 6, the cladding layer 1 was used as the barrier layer.
A barrier layer having the same lattice constant as that of the well layers 4 and 18 was used. However, when the strain of the well layer is large, the strain composition is used, and the strain direction is compensated for by making the strain direction opposite to the well layer. And a good quantum well structure can be obtained.

Further, as in Embodiment 6, the GaAs substrate 1
The plane orientation of 1 is 0 ° from the (100) plane in the [011] direction.
From the (100) plane to [0.
11] in the range of 10 ° to 54.7 °, the formation of a natural superlattice can be suppressed, so that the band gap can be prevented from decreasing.
4, 18, and the light guide layers 15, 17 are preferable because they have a wide gap. In the sixth embodiment, the lattice relaxation buffer layers 12 and 13 and the heterojunction are grown by MOCVD, but they can also be grown by MBE (molecular beam epitaxy).

Example 7 In Example 7, 635 n of the light guide layer containing no Al was used.
m, 650 nm, etc.
You. In the seventh embodiment, first, the (011) direction from the (100) plane
MOCVD method on the GaP substrate 11 turned off by 15 °
Gradually changes the Ga composition from 1 to 0.78.
And Se is 5 × 10¹⁸cm^-3Film thickness doped above
Is 2 μm n-GaInP graded buffer layer 12
Are laminated, and 5 × 10¹⁸cm^-3more than
Doped n-Ga_0.78In_{0.2 2}Film consisting of P
A uniform composition layer 13 having a thickness of 1 μm is grown to reduce lattice mismatch.
Let it sum. Doping Se at a high concentration can relax the lattice.
Cross-hatch irregularities associated with the sum were reduced. That is,
N-Ga doped with Se_0.78In_0.22P composition
The upper surface of the interface of the uniform layer was flatter than the lower surface (substrate side).
As a result, the origin and unevenness when the heterojunction was grown
New crystal defects can be prevented. Next, G
The lattice constant between aP and GaAs, where Ga_0.78
In_0.22N- (Al equal to the lattice constant of P_yGa
_1-y)_βIn_1-βP_vAs_1-v(y = 0.7, β =
0.78, v = 1) Cladding layer 14 (film thickness 1 μm), A
l (Al _zGa_1-z)_γIn_1-γP_uAs
_1-u(z = 0, γ = 0.78, u = 1) Light guide layer 15
(Thickness: 0.1 μm), compressed as shown in FIG.
With strain (Al_xGa_1-x)_αIn_1-αP_tAs
_1-t(x = 0, α = 1, t = 0.3) Compression strain quantum well layer
16 (film thickness 8 nm) and not containing Al (Al_zGa
_1-z)_γIn_1-γP_uAs_1-u(z = 0, γ = 0.
78, u = 1) alternately with three barrier layers (thickness: 10 nm)
Multi-quantum well active layer 16 stacked on the substrate, not containing Al
(Al _zGa_1-z)_γIn_1-γP_uAs_1-u(z =
0, γ = 0.78, u = 1) The light guide layer 17 (having a thickness of 0.
1 μm), p- (Al_yGa_1-y)_βIn_1-βP_vAs
_1-v(y = 0.7, β = 0.78, v = 1) Cladding layer
18 (film thickness 1 μm), p-Ga_0.7In_0.3PC
Layer 19 (thickness: 0.1 μm), p-GaP contact
A layer 20 (with a thickness of 0.005 μm) is grown. Cladding layer
The light guide layers 15, 17 and the light guide layers 15, 17 are Ga_0.78
In_0.22It is lattice-matched to P.

Then, SiO ₂ as an insulating film 21 and a p-side electrode 22 are formed on the contact layer 20, and an n-side electrode 23 is formed on the back surface of the substrate 11. Although this semiconductor light emitting device is configured as an insulating film stripe structure, other structures can be used.

In the lattice constants of the cladding layers 14 and 18 in the seventh embodiment, even if GaInP having a small band gap is used among AlGaInP, strain must be increased to obtain 635 nm, and crystallinity is lowered. , Well layer 1
In No. 6, As was added to adjust the band gap.

According to the structure of the seventh embodiment, a semiconductor laser oscillating at a wavelength of 635 nm was obtained. The polarization was in TE mode. Cladding layers 14, 18 and light guide layers 15, 1
7 has a wider gap than a conventional material system lattice-matched to a GaAs substrate, and the carrier confinement is improved.
In addition to the effect of the compressive strain and the effect of the quantum well, a wide gap material can be used as the compressive strain quantum well layer. As a result, the well width was increased, and the adverse effect of the interface was reduced. In addition, the light guide layers 15, 17
And the well layer 16 does not contain Al.
The non-radiative recombination current caused by Al was reduced, and the luminous efficiency was improved. In addition, the surface recombination current was reduced, the level of end face light degradation was remarkably improved, and a high output was obtained. As a result, a red laser that operates stably at high temperature and high output was obtained.

The composition of the cladding layers 14 and 18 is determined according to the active layer 1
6 and a band gap larger than that of Al (Al _y
Ga _1-y ) _β In _{1-β Pv} As _1-v (0 <y ≦ 1,
0.5 <β <1, 0 <v ≦ 1) can be used.
Although the lattice constant changes depending on the value of β of the cladding layers 14 and 18, it can be dealt with by changing the lattice constant of the uppermost surface of the lattice relaxation buffer layers 12 and 13 to be the same as that of the cladding layer 14.

Further, as in Embodiment 7, the GaAs substrate 1
The plane orientation of 1 is 0 ° from the (100) plane in the [011] direction.
From the (100) plane to [0.
11] in the range of 10 ° to 54.7 °, the formation of a natural superlattice can be suppressed, so that the band gap can be prevented from decreasing.
4 and 18 and the light guide layers 15 and 17 are preferable because they have a wide gap. In the seventh embodiment, the lattice relaxation buffer layers 12 and 13 and the heterojunction are grown by MOCVD, but they can also be grown by MBE (molecular beam epitaxy).

Embodiment 8 FIG. 8 is a view showing a semiconductor light emitting device (semiconductor laser device) of Embodiment 8. The layer structure is an SCH-SQW structure. Example 8 is an example using a GaPAs substrate. That is, in Example 8, GaPAs in which the P composition was gradually changed from 0 to 0.4 by the VPE method (vapor phase growth) was formed on the GaAs substrate 31 which was turned off by 15 ° in the [011] direction from the (100) plane. The graded layer 32 is stacked with a thickness of 30 μm, and a uniform composition layer 33 made of GaP _0.4 As _0.6 is grown thereon with a thickness of 20 μm, and the thickness of the grown layer thus grown. For example, GaP of 50 μm
An As substrate 34 is used. Here, the GaPAs substrate 3
Reference numeral 4 denotes an epi-substrate which has grown on a GaAs or GaP substrate to a thickness of, for example, 30 μm or more by VPE or the like. Lattice mismatch is sufficiently mitigated on the surface of the growth layer,
It can be called a GaPAs substrate.

In the eighth embodiment, a Se-doped n-Ga _0.7 In _0.3 P buffer layer 35 (1 μm thick) is grown by MOCVD, and the surface is flattened. Next, n- (Al is a lattice constant between GaP and GaAs, which is equal to the lattice constant of GaP _0.4 As _0.6.
y Ga _1-y ) _β In _{1-β Pv} As _1-v (y = 0.
7, β = 0.7, v = 1) Cladding layer 36 (1 μm thick)
_{m), (Al z Ga 1} -z) γ In 1-γ P u As 1-u
(z = 0.1, γ = 0.7, u = 1) Light guide layer 37 (0.1 μm in thickness), having compressive strain (Al _x Ga _1-x )
_α In _{1−α Pt} As _{1− t} (x = 0, α = 0.55,
t = 1) Single quantum well active layer 38 (8 nm thick), (Al
_z Ga _1-z ) _γ In _{1-γ Pu} As _1-u (z = 0.
1, γ = 0.7, u = 1) Light guide layer 39 (having a film thickness of 0.
_{1μm), p- (Al y Ga} 1-y) β In 1- β P v As
_1-v (y = 0.7, β = 0.7, v = 1) cladding layer 4
0 (thickness 1 μm), p-Ga _0.7 In _0.3 P cap layer 41 (thickness 0.1 μm), and p-GaAs contact layer 42 (thickness 0.05 μm) are grown. Clad layer 3
6, 40 and the light guide layers 37, 39 are lattice-matched to the GaPAs substrate 34. Then, the contact layer 42
On the upper surface, SiO ₂ as an insulating film 43 and a p-side electrode 44 are formed, and on the back surface of the substrate 31, an n-side electrode 45 is formed. Although this semiconductor light emitting device is configured as an insulating film stripe structure, other structures can be used.

With the structure of Example 8, a semiconductor laser oscillating at a wavelength of 635 nm was obtained. The polarization was in TE mode. The cladding layers 36 and 40 and the light guide layer 37,
39 has a wider gap than a conventional material system lattice-matched to a GaAs substrate, and the carrier confinement is improved. In addition to the effect of the compressive strain and the effect of the quantum well, a wide gap material can be used as the compressive strain quantum well layer. The well width was increased and the adverse effects of the interface were reduced. In addition, conventionally, A
The l composition was reduced, and the light output level at which the end face light deteriorated was increased. As a result, a laser capable of operating stably at high temperature and high output was obtained.

The composition of the cladding layers 36 and 40 is
It has a larger band gap and contains Al (Al _y G
a _1-y ) _β In _{1−β Pv} As _1−v (0 <y ≦ 1,
0.5 <β <1, 0 <v ≦ 1) can be used.
Optical guide layer 37 and 39, the band gap is larger lattice constant smaller than the active layer than the cladding layer is the same as cladding layer _{(Al z Ga 1-z)} γ In 1-γ P u As
_1-u (0 ≦ z <1, 0.5 <γ <1, 0 <u ≦ 1) can be used. In the eighth embodiment, a multiple quantum well using a single quantum well active layer may be used. The lattice constant changes depending on the value of β of the cladding layers 36 and 40.
The lattice constant of the uppermost surface of the aPAs substrate 34 is
It can be dealt with by changing it to be the same as 6,40.
Further, as in Example 8, the plane orientation of the GaAs substrate is
0 ° to 54.7 ° in the [011] direction from the (100) plane, or 10 ° in the [011] direction from the (100) plane.
If the angle is in the range of from 5 ° to 54.7 °, the formation of the natural superlattice can be suppressed, so that the band gap can be prevented from being reduced. preferable.

Ninth Embodiment FIG. 9 is a diagram showing a semiconductor light emitting device (semiconductor laser device) according to a ninth embodiment. Example 9 is an example of application to a red laser of 635 nm, 650 nm, or the like using a light guide layer containing no Al. The layer structure is an SCH-MQW structure. In Example 9, first, the P composition was gradually changed from 1 to 0.55 by the VPE method (vapor phase growth) on the GaP substrate 51 turned off by 15 ° in the [011] direction from the (100) plane. A GaPAs graded layer 52 is laminated with a thickness of 30 μm, and a uniform composition layer 53 made of GaP _0.55 As _0.45 is grown thereon with a thickness of 20 μm, and the thickness of the grown layer thus grown. For example, GaPAs of 50 μm
A substrate 54 is used.

In the ninth embodiment, before crystal growth of the heterojunction, the surface of the GaPAs substrate 54 having the cross-hatch-shaped irregularities was flattened (lapping interface) by mechanical polishing. did. Further, the surface was removed by slightly etching the surface with a chemical solution to remove damage due to polishing. Thereby, it is possible to prevent the generation of new crystal defects when a heterojunction portion originating from the unevenness is grown.

Next, n-Ga is formed by MOCVD.
_0.78In_0.22A 0.3 μm thick P
Buffer layer 55, the lattice constant between GaP and GaAs.
Tte Ga _0.78In_0.22N equal to the lattice constant of P
− (Al_yGa_1-y)_βIn_{1 −β}P_vAs_1-v(Y
= 0.7, β = 0.78, v = 1) cladding layer 56 (film
Thickness is 1 μm) and does not contain Al (Al_zGa_1-z)_γI
n_1-γP_uAs_1-u(z = 0, γ = 0.78, u =
1) Optical guide layer 57 (thickness: 0.1 μm), with compressive strain
(Al_xGa_1-x)_αIn_1-αP_tAs
_1-t(x = 0, α = 1, t = 0.3) (film thickness 8 nm)
And not containing Al (Al_zGa_1-z)_γIn_1-γP_u
As_1-u(z = 0, γ = 0.78, u = 1) Barrier layer (film
Multiple quantum wells alternately stacked in three layers
Door active layer 58, not containing Al (Al_zGa _1-z)_γI
n_1-γP_uAs_1-u(z = 0, γ = 0.78, u =
1) Light guide layer 59 (0.1 μm thick), p- (Al_y
Ga_1-y)_βIn_1-βP_vAs_{1 -V}(y = 0.7,
β = 0.78, v = 1) cladding layer 60 (film thickness 1 μm)
m), p-Ga_0.7In_0.3P cap layer 61 (film
P-GaP contact layer 62 (thickness: 0.1 μm)
Grows 0.005 μm). Cladding layers 56 and 60
And the guide layers 57 and 59 are made of Ga._0.78In_0.22
It is lattice-matched to P.

On the contact layer 62, SiO ₂ as an insulating film 63 and a p-side electrode 64 are formed, and on the back surface of the substrate 51, an n-side electrode 65 is formed. Although this semiconductor light emitting device is configured as an insulating film stripe structure, other structures can be used.

Regarding the lattice constants of the cladding layers 56 and 60 of Example 9, even if GaInP having a small band gap is used among AlGaInP, strain must be increased to obtain 635 nm, and there is a concern that crystallinity may be deteriorated. So that
As was added to the well layer 58 to adjust the band gap.

According to the structure of the ninth embodiment, a semiconductor laser oscillating at a wavelength of 635 nm was obtained. The polarization was in TE mode. Cladding layers 56 and 60 and light guide layers 57 and 5
9 has a wider gap than a conventional material system lattice-matched to a GaAs substrate, and the carrier confinement is improved.
In addition to the compressive strain effect and the quantum well effect, a wide gap material can be used for the compressive strain quantum well layer. The width was increased and the adverse effects of the interface were reduced. In addition, since the light guide layers 57 and 59 and the well layer 58 have a structure that does not contain Al, the non-radiative recombination current caused by Al is reduced, and the luminous efficiency is improved. In addition, the surface recombination current is reduced, the level of end face light degradation is improved, and a high output is obtained. As a result, a red laser that operates stably at high temperature and high output was obtained.

The composition of the cladding layers 56 and 60 is
The band gap was larger and Al was contained (Al _y Ga
_1-y ) _β In _{1−β Pv} As _1−v (0 <y ≦ 1, 0.
5 <β <1, 0 <v ≦ 1) can be used. Although the lattice constant changes depending on the value of β of the cladding layers 56 and 60, it can be dealt with by changing the lattice constant of the uppermost surface of the lattice relaxation buffer layer to be the same as that of the cladding layer.

Also, as in Embodiment 9, the plane orientation of the GaPAs substrate is in the range of 0 ° to 54.7 ° in the [011] direction from the (100) plane or [011] from the (100) plane.
1] in the range of 10 ° to 54.7 °, the formation of the natural superlattice can be suppressed, so that the band gap can be prevented from being reduced.
It is preferable because the light guide layer has a wide gap. In the ninth embodiment, the heterojunction is grown by the MOCVD method. However, it can be grown by the MBE method (molecular beam epitaxy).

Embodiment 10 FIG. 10 shows a semiconductor light emitting device (semiconductor laser device) of Embodiment 10.
FIG. In Example 10, the layer structure was S
It is a CH-SQW structure. In the tenth embodiment, first, (1
GaP turned off by 2 ° in the [110] direction from the (00) plane
_0.4As_0.6VPE method (vapor phase growth) on substrate 71
Thus, Ga in which the P composition was gradually changed from 0 to 0.4
The PAs graded layer 72 is laminated with a thickness of 30 μm,
GaP on it _0.4As_0.6Composition uniform layer 7 consisting of
3 was grown to a film thickness of 20 μm.
A GaPAs substrate 74 having a long layer thickness of, for example, 50 μm is used.
Have been. Here, the GaPAs substrate refers to a VPE method or the like.
30 μm or more on GaAs or GaP substrate
It is an epi-substrate that has grown thick. The surface of the growth layer is case
The child mismatch is sufficiently relaxed, and it can be said that it is a GaPAs substrate.
You.

Next, n-GaP is formed by MOCVD.
_0.4As_0.6Buffer layer 75 (thickness: 1 μm), Ga
The lattice constant between P and GaAs, GaP_0.4A
s_{0 . 6}N- (Al containing As equal to the lattice constant of_yG
a_1-y)_βIn_1-βP_vAs_1-v(Y = 0.5, β
= 0.8, v = 0.85) Cladding layer 76 (film thickness 1 μm)
m), (Al_zGa_1-z)_γIn_1-γP_uAs_1-u
(z = 0, γ = 0.7, u = 1) Light guide layer 77 (film thickness
0.1 μm) and has compressive strain (Al_xGa _1-x)_α
In_1-αP_tAs_1-t(x = 0, α = 0.65, t
= 0.9) Single quantum well active layer 78 (film thickness 25n
m), (Al_zGa_1-z)_γIn_1-γP_uAs_1-u
(z = 0, γ = 0.7, u = 1) Light guide layer 79 (film thickness
Is 0.1 μm), p- (Al_yGa_1-y)_βIn_1-β
P_vAs_1-v(y = 0.5, β = 0.8, v = 0.8
5) Cladding layer 80 (1 μm thickness), p-Ga_0.7
In_{0. 3}P cap layer 81 (thickness: 0.1 μm), p
-GaP_0.4As_0.6Contact layer 82 (film thickness
0.2 μm). Cladding layers 76, 80 and
The light guide layers 77 and 79 are grid-aligned on the GaPAs substrate 74.
I agree.

On the contact layer 82, SiO ₂ as an insulating film 83 and a p-side electrode 84 are formed, and on the back surface of the substrate 71, an n-side electrode 85 is formed. Although this semiconductor light emitting device is configured as an insulating film stripe structure, other structures can be used.

According to the structure of the tenth embodiment, the wavelength is 660 nm.
A semiconductor laser oscillating at the above was obtained.

In Example 10, GaP _0.4 As _0.6
The plane orientation of the substrate 71 is 2 in the [110] direction from the (100) plane.
° Off and slight inclination. Such (1
Gap, GaAs with small inclination from (00) plane or (100)
When AlGaInP was grown on the s, GaP _0.4 As _0.6 substrate by MOCVD, many hillocks were observed on the growth surface. This hillock was particularly remarkable in the case where the Al composition was large, such as AlInP, as compared with GaInP. If a large number of hillocks are present in the growth layer, the characteristics of devices such as lasers and LEDs are deteriorated, and the yield is lowered, which is not preferable in production. Particularly, in the laser as in the tenth embodiment, the influence is great because the cladding layers 76 and 80 are thick. The inventors of the present application have reported that AlGaI
It has been found that the hillock density can be reduced by including As during nP growth. This is presumably because the formation of Al or Ga droplets is suppressed. As a result, it was possible to suppress the deterioration of the device characteristics and the decrease in the yield. Further, since the light guide layers 77 and 79 and the well layer 78 have a structure that does not contain Al, A
The non-radiative recombination current due to 1 was reduced, and the luminous efficiency was improved. In addition, the surface recombination current was reduced, the level of end face light degradation was remarkably improved, and a high output was obtained. As a result, a red laser that operates stably at high temperature and high output was obtained.

Although the single quantum well active layer is used in the tenth embodiment, a multiple quantum well may be used. In that case, the barrier layer
(Al _x2 Ga _1-x2 ) _α2 In _{1-α2 Pt2} As
_{1−t 2} (0 ≦ x2 <1, 0.5 <α2 ≦ 1, 0 ≦ t2
≦ 1) can be used. Also, the light guide layer 77,
79 may include As.

The semiconductor laser described above is also effective when applied to a light emitting diode (LED). In this case, a visible LED with high luminance and good temperature characteristics can be obtained.

[0120]

As described above, according to the first aspect of the present invention, a semiconductor in which a heterojunction having an active layer for generating light and a cladding layer for confining light is formed on a semiconductor substrate. In the light emitting device, the active layer is (Al _x
Ga _1−x ) _α In _{1−α Pt} As _1−t (0 ≦ x <1,
0 <consists α ≦ 1,0 ≦ t ≦ 1) , the cladding layer is larger band gap than the active layer, containing Al having a lattice constant between the GaP and _{GaAs (Al y Ga 1-y} )
_β In _{1−β Pv} As _1−v (0 <y ≦ 1, 0.5 <β <
1, 0 <v ≦ 1), the band gap is larger than the cladding layer material that can be formed on the GaAs substrate, which is advantageous for shortening the wavelength. The active layer is made of (Al _x G
a _1−x ) _α In _{1−α Pt} As _1−t (0 ≦ x <1,0
<Α ≦ 1, 0 ≦ t ≦ 1), the cladding layer can be strained, and can have a narrower gap than conventional materials. For this reason, the range of element design is greatly expanded compared to the related art, and excellent characteristics can be obtained not only for light emitting elements having a wavelength shorter than 600 nm but also for light having a longer wavelength. As a result, a high-temperature, high-output, stable operation of the red semiconductor laser of 635 nm, 650 nm band,
A visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like can be provided.

According to the second aspect of the present invention, the semiconductor device
An active layer that emits light and a
Semiconductor device having a heterojunction having a pad layer
In an optical device, the active layer is made of (Al_xGa_1-x)_αIn
_1-αP_tAs_1-t(0 ≦ x <1, 0 <α ≦ 1, 0 ≦
t ≦ 1) Consists of a single quantum well, and the cladding layer is
Band gap is large, and the gap between GaP and GaAs is large.
Al having a lattice constant was included (Al_yGa_1-y)_βI
n_1-βP_vAs_1-v(0 <y ≦ 1, 0.5 <β <1,
0 <v ≦ 1), and between the active layer and the cladding layer,
Band gap is larger than active layer and smaller than cladding layer
(Al_zGa_1-z)_γIn_1-γP_uAs_1-u(0
≦ z <1, 0.5 <γ <1, 0 <u ≦ 1)
And a cladding layer made of GaP and GaAs.
(Al having a lattice constant between_yGa
_1-y)_βIn_1-βP_vAs_1-v(0 <y ≦ 1, 0.
5 <β <1, 0 <v ≦ 1) and formed on a GaAs substrate
Larger band gap and shorter wavelength than possible cladding layer material
It is advantageous for lengthening. In addition, (Al_zGa_1-z)_γIn
_1-γP _uAs_1-u(0 ≦ z <1, 0.5 <γ <1,
0 <u ≦ 1) and a light guide layer (Al)_xGa
_1-x)_αIn_1-αP_tAs_1-t(0 ≦ x <1, 0 <
α ≦ 1, 0 ≦ t ≦ 1)
Since the H structure is formed, the GaAs substrate lattice matching material
To obtain wide gap with less Al composition
The Al composition of the light guide layer can be reduced as compared with the related art,
Reduction of non-radiative recombination current and surface recombination current
Light emission efficiency can be improved.
The end face is less likely to deteriorate, and stable operation is possible even at high output.
You. Also, it may have a strain on the cladding layer.
And a narrower gap than conventional materials
Wear. Further, GaInP has a lattice structure when the Ga composition is reduced.
As the constant increases, the band gap decreases.
You. Sandip et al. (Appl. Phys. Lett.
60, 1992, pp. 630-632)
With reference to the continuous estimation, the change in band gap
Occurs on the conduction band side, and the energy on the valence band side is almost
No change. In other words, even if the composition is changed, the valence band
The change in energy is small. On the other hand, Al to GaInP
When added, the conduction band energy increases and the valence band energy increases.
Energy is reduced. The change is larger on the valence band side
Good. Conventionally, a structure on a GaAs substrate has a large Al composition.
AlGaInP must be used as the light guide layer,
The band gap between the valence band and the InP quantum well layer is large.
Had continuity. In other words, the band discontinuity on the conduction band side is
It was not big enough. In contrast, according to the present invention,
For example, since the Al composition of the light guide layer can be reduced,
A conduction band discontinuity is obtained. Thereby, the conventional AlGa
Conduction band side which was a problem with red laser using InP-based material
(Electron) over due to small band discontinuity
-Flow can be significantly improved. For this reason,
Since the width of element design has been greatly expanded,
Light-emitting elements with wavelengths longer than 600 nm as well as shorter wavelengths
Good characteristics can also be obtained in the child. This
635nm, 650n which operates stably at high temperature, high output and
m-band and other red semiconductor lasers, at room temperature from 600 nm
Visible semiconductor laser oscillating at short wavelength and high luminous efficiency
A visual light emitting diode or the like can be provided.

According to the third aspect of the present invention, the semiconductor device
An active layer that emits light and a
Semiconductor device having a heterojunction having a pad layer
In an optical device, the active layer is composed of a well layer and a barrier layer.
Quantum well structure, and the well layer is made of (Al_x1Ga
_1-x1)_α1In_1-α1P_t1As_1-t1(0 ≦ x
1 <1, 0 <α1 ≦ 1, 0 ≦ t1 ≦ 1)
The layer is (Al_x2Ga_1-x2) _α2In_1-α2P_t2A
s_1-t2(0 ≦ x2 <1, 0.5 <α2 <1, 0 ≦ t
2 ≦ 1), and the cladding layer is more bandgap than the active layer.
Large gap with lattice constant between GaP and GaAs
(Al_yGa_1-y)_βIn_{1- β}P_vA
s_1-v(0 <y ≦ 1, 0.5 <β <1, 0 <v ≦ 1)
Band gap between the active layer and the cladding layer.
Is larger than the active layer and smaller than the cladding layer (Al_zGa
_1-z)_γIn_1-γP_uAs_1-u(0 ≦ z <1, 0.
5 <γ <1, 0 <u ≦ 1)
The cladding layer has a lattice constant between GaP and GaAs.
Containing Al (Al_yGa_1-y)_βIn
_1-βP_vAs_1-v(0 <y ≦ 1, 0.5 <β <1, 0
<V ≦ 1), and a clad that can be formed on a GaAs substrate
Larger band gap than layer material, advantageous for shorter wavelength
is there. In addition, (Al_zGa_1-z)_γIn_1-γP_uAs
_1-u(0 ≦ z <1, 0.5 <γ <1, 0 <u ≦ 1)
Light guide layer and (Al_x1Ga_1-x1) _α1I
n_1-α1P_t1As_1-t1(0 ≦ x1 <1, 0 <α
A quantum well consisting of 1 ≦ 1, 0 ≦ t1 ≦ 1 and (Al_x2G
a_1-x2)_α2In_1-α2P_t2As _1-t2(0 ≦
x2 <1, 0 <α2 ≦ 1, 0 ≦ t2 ≦ 1)
Since the SCH structure is formed by the layers,
The Al composition of the light guide layer can be reduced, and the non-radiative recombination current can be reduced.
Improved luminous efficiency by reducing the surface recombination current
In the case of a laser, the end face is hardly deteriorated.
Thus, stable operation is possible even at high output. Also clad
The well layer may have a strain with respect to the layer, and the barrier layer may have a strain.
By setting the strain direction to the opposite direction to the well layer,
It is also possible to obtain a good quantum well structure by compensating for only the quantum well structure.
In addition, by using a multiple quantum well structure, sufficient carriers can be provided.
It becomes possible to confine it in the well layer. In addition, conventional materials
A narrower gap can be used. Further, Ga
InP has a large lattice constant when the Ga composition is reduced.
And the band gap becomes smaller. Sandi
p, et al. (Appl. Phys. Lett. 60, 199).
2, pp 630-632)
The band gap change on the conduction band side
The energy on the valence band side has hardly changed
No. In other words, even if the composition is changed, the energy of the valence band does not change.
The transformation is small. On the other hand, when Al is added to GaInP,
Conduction energy is large and valence band energy is small
It becomes. The change is larger on the valence band side. Conventionally, G
AlGaInP with large Al composition in a structure on aAs substrate
Must be a light guide layer, and a GaInP quantum well layer
Has a large valence band discontinuity between
Was. In other words, the band discontinuity on the conduction band side is large enough
There was no. In contrast, according to the present invention, the light guide layer
Large conduction band discontinuity
The continuation is obtained. Thereby, the conventional AlGaInP-based material
Band discontinuity on the conduction band which was a problem with red lasers
Carrier (electron) overflow due to small continuity
Temperature characteristics are good at low thresholds.
Was. For this reason, the range of element design is greatly expanded compared to the conventional case.
Therefore, not only wavelengths shorter than 600 nm but also 600 nm
Good characteristics even for light emitting elements with longer wavelength
be able to. This allows high temperature, high output, and stable operation.
635nm, 650nm band red semiconductor laser, room temperature
Semiconductor oscillating at wavelengths shorter than 600 nm
Providing lasers and visible light emitting diodes with high luminous efficiency
Can be

According to the fourth aspect of the present invention,
The semiconductor light emitting device according to claim 1.
In the device, the active layer contains As (Al_xGa
_1-x) _αIn_1-αP_tAs_1-t(0 ≦ x <1, 0 <
α1 ≦ 1, 0 ≦ t ≦ 1), and the addition of As
Since the band gap is reduced, the lattice constant becomes GaP.
When using a cladding layer with a large band gap
Even in the case of 635nm, 650nm band, etc., from 600nm
Applicable to long wavelength devices. That is, the conventional GaAs
Larger than the 635 nm and 650 nm band devices on the substrate
Layer with a high band gap,
Good element characteristics such as low bar flow and stable operation at high temperature
Sex can be obtained. As a result, high temperature, high output,
Red semiconductor lasers in the 635nm, 650nm band etc.
To provide visible light emitting diodes with high luminous efficiency
be able to.

According to a fifth aspect of the present invention, in the semiconductor light emitting device according to any one of the second to fourth aspects, the light guide layer is made of Ga _γ In containing no Al.
_{1-γ Pu} As _1-u (0.5 <γ <1, 0 <u ≦ 1). That is, when the lattice constant is smaller than GaAs, the band gap increases, and to obtain a material having the same band gap, Al
The composition can be reduced. For this reason, the Al composition of the light guide layer can be reduced as compared with the related art. For example, in a red laser on a GaAs substrate, (Al _0.5 Ga _0.5 ) _0.5 In _0.5 P having a band gap wavelength of about 570 nm is usually used, but GaP and GaAs of the present invention are used. According to the material having a lattice constant between, _{Ga 0.7} containing no Al
In _0. This band gap wavelength is achieved by ₃ P. Therefore, even in a red laser having a wavelength of 635 nm or 650 nm or the like, the active region can be formed of a material containing no Al, and the non-radiative recombination current and the surface recombination current caused by Al can be reduced, thereby improving the luminous efficiency. The end face is hardly deteriorated, and stable operation is possible even at high output. Accordingly, it is possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably at a high temperature, a high output, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to a sixth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to fifth aspects, the cladding layer contains As (Al _y G
_{a 1 -y) β In 1-} β P v As 1-v (0 <y ≦ 1,
0.5 <β <1, 0 <v <1).
By including As during the growth of aInP, the density of hillocks can be drastically reduced, so that deterioration of device characteristics and reduction in yield can be suppressed. This makes it possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably at a high temperature, a high output, a visible semiconductor laser that oscillates at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like. .

According to the seventh aspect of the present invention, in the semiconductor light emitting device according to any one of the second to sixth aspects, the lattice constant of the well layer is larger than that of the cladding layer, and compressive strain is reduced. It is characterized by having. In a conventional 635 nm band laser on a GaAs substrate, a material having a small band gap (mainly GaIn
P), the well width becomes too narrow, the influence of the interface becomes large, and it is difficult to obtain good performance. Therefore, a tensile strain well layer is used. For this reason, the polarization was in the TM mode. On the other hand, according to the present invention, since the band gap is increased, even if a material having a larger lattice constant than the cladding layer is used for the well layer, a quantum well layer having an optimum thickness can be formed, and a high-performance compressive strain can be obtained. A 635 nm band laser structure can be easily obtained. In addition, by having a compressive strain, the polarized light is in the TE mode, becomes the same as a laser of another general wavelength band, and can be used without changing the optical system, which is convenient in application. As a result, a high-temperature, high-output, stable operation of the red semiconductor laser of 635 nm, 650 nm band,
A visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like can be provided.

According to an eighth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to seventh aspects, the semiconductor substrate is made of GaPAs, and a hetero junction is formed on the semiconductor substrate. Is characterized by crystal growth. G, which is the lattice constant between GaP and GaAs
aPAs are deposited on GaP or substrate thickly (eg, 30 μm).
m) and can be substantially grown as a GaPAs substrate by VPE (vapor phase epitaxy) or the like. By setting the uppermost portion to be the same as the lattice constant of the hetero junction (at least the cladding layer), the present material system can be grown without lattice irregularity. Accordingly, it is possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably at a high temperature, a high output, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to a ninth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to seventh aspects, the semiconductor substrate is made of GaAs or GaP, and the semiconductor substrate and the cladding layer are In between, a heterojunction is crystal-grown via a relaxation buffer layer for alleviating the lattice mismatch between the two, and a heterojunction is formed on the GaAs or GaP substrate via the relaxation buffer layer for relaxing the lattice mismatch. This alleviates the lattice mismatch and allows the heterojunction to grow. In addition, the same crystal growth apparatus can be used for continuous and continuous growth, and only one apparatus is required. Accordingly, it is possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably at a high temperature, a high output, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to a tenth aspect of the present invention, in the semiconductor light emitting device of the ninth aspect, the relaxation buffer layer has a cladding layer whose lattice constant gradually changes from the lattice constant of the semiconductor substrate in the growth direction. Because the lattice relaxation gradually occurs by using the graded layer as a relaxation buffer layer,
Threading dislocations can be prevented from growing above the graded layer, and the crystallinity of the hetero junction does not need to be reduced. Thereby, high temperature, high output, and stable operation 635
It is possible to provide a red semiconductor laser having a wavelength of 650 nm or 650 nm, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode having high luminous efficiency, and the like.

According to the eleventh aspect of the present invention, in the semiconductor light emitting device according to the ninth aspect, the relaxation buffer layer has a strained superlattice structure in which at least two kinds of materials having different lattice constants are alternately laminated. By using a strained superlattice structure as a relaxation buffer layer, crystal defects caused by lattice relaxation can be confined within the strained superlattice structure, and a decrease in crystallinity of a heterojunction can be prevented. As a result, 635 nm, 650 capable of high temperature, high output, and stable operation
nm semiconductor red laser, 600nm at room temperature
A visible semiconductor laser oscillating at a shorter wavelength, a visible light emitting diode with high luminous efficiency, and the like can be provided.

According to the twelfth aspect of the present invention, in the semiconductor light emitting device according to the ninth aspect, the relaxation buffer layer comprises a low-temperature buffer layer grown at a temperature lower than the growth temperature of the cladding layer. By using the layer as a relaxation buffer layer, crystal defects caused by lattice relaxation can be confined in the low-temperature buffer layer, and a decrease in the crystallinity of the hetero junction can be prevented. This allows
It is possible to provide a red semiconductor laser in a 635 nm, 650 nm band or the like that operates at a high temperature, a high output, and stably, a visible semiconductor laser that oscillates at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to a thirteenth aspect of the present invention, in the semiconductor light emitting device according to any one of the ninth to twelfth aspects, the relaxation buffer layer is made of GaInP or GaPAs. . GaPAs
Alternatively, GaInP is a ternary material and is easy to control. When using GaPAs, it is only necessary to add As to GaP when the semiconductor substrate is a GaP substrate, and it is only necessary to add P to GaAs when the semiconductor substrate is a GaAs substrate, and control is easy. In the case of GaInP, since only P is a group V having a high vapor pressure, it is easy to control the interface particularly when growing a strained superlattice structure. Accordingly, it is possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably at a high temperature, a high output, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to the fourteenth aspect of the present invention, in the semiconductor light emitting device according to the eighth or ninth aspect,
The plane orientation of the semiconductor substrate may be a plane inclined from 0 ° to 54.7 ° in the [011] direction from the (100) plane, or (10).
A plane inclined from 10 ° to 54.7 ° in the [0-11] direction from the (0) plane or a plane equivalent thereto, and the plane orientation of the semiconductor substrate is [011] from the (100) plane. ]
Direction from 0 ° to 54.7 °, or (100)
Inclined from the plane in the range of 10 ° to 54.7 ° in the [0-11] direction, the formation of a natural superlattice can be suppressed, and the wide gap with the same composition ratio as compared to the case where the natural superlattice is formed This is advantageous for shortening the wavelength. In addition, an end face type laser usually uses a cleavage plane for a resonator. If the plane orientation of the substrate is tilted in the above direction, the cleavage plane in the direction perpendicular to the tilted direction will not be perpendicular, but if it is cleaved in the tilted direction, a vertical plane will be obtained and a laser cavity can be formed. It is not preferable to incline in the direction other than the above direction, since the cleavage plane does not become vertical. Further, by inclining the plane orientation of the substrate from the (100) plane, the hillock density can be reduced, thereby suppressing the deterioration of device characteristics and the decrease in yield. As a result, the 635n which operates stably at high temperature, high output and
It is possible to provide a red semiconductor laser in the m, 650 nm band or the like, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to a fifteenth aspect of the present invention, in the semiconductor light emitting device according to the eighth or ninth aspect,
Prior to crystal growth of the heterojunction, GaPAs
The substrate surface is flattened by mechanical polishing, or the surface after growth of the relaxation buffer layer and before crystal growth of the heterojunction is flattened by mechanical polishing. On the surface of the GaPAs substrate or the surface after growth of the relaxation buffer layer, cross-hatched irregularities related to lattice irregularity are usually formed. This unevenness may be a source of new crystal defects when a heterojunction is grown thereon. This can be prevented by flattening by polishing and growing a heterojunction thereon. As a result, 635 nm, 65 high temperature, high output, and stable operation can be achieved.
0 nm band red semiconductor laser, 600n at room temperature
It is possible to provide a visible semiconductor laser oscillating at a wavelength shorter than m, a visible light emitting diode with high luminous efficiency, and the like.

According to the sixteenth aspect of the present invention, in the semiconductor light emitting device according to the eighth or ninth aspect,
The semiconductor device is characterized in that a layer whose upper surface at the interface of the layer is flatter than the lower surface (substrate side) is provided between the semiconductor substrate and the hetero junction. On the surface of the GaPAs substrate or the surface after growth of the relaxation buffer layer, cross-hatched irregularities related to lattice irregularity are usually formed. The irregularities can be a source of new crystal defects when a heterojunction is grown thereon. When a layer that grows by embedding such irregularities is included, the upper layer becomes flat, which can be prevented.
As a result, high-temperature, high-output, stable operation of 635 nm,
Red semiconductor laser of 650 nm band or the like, 60 at room temperature
A visible semiconductor laser oscillating at a wavelength shorter than 0 nm, a visible light emitting diode with high luminous efficiency, and the like can be provided.

According to the seventeenth aspect of the present invention, in the semiconductor light emitting device according to the sixteenth aspect, the upper surface of the interface of the layer is flatter than the lower surface (substrate side), and the layer has Se of 5 × 10
It is characterized by being GaInP doped to ¹⁸ cm ^-3 or more. The inventor of the present application has found that GaInP doped with Se at a high concentration has a property of growing by embedding irregularities. As a result, the upper surface of the interface between the layers becomes flatter than the lower surface (substrate side), so that it is possible to prevent the occurrence of new crystal defects originating in the irregularities when the heterojunction is grown. Accordingly, it is possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably at a high temperature, a high output, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to the invention described in claim 18, in the semiconductor light-emitting device according to claim 9, the relaxation buffer layer is formed of Ga doped with Se to 5 × 10 ¹⁸ cm ⁻³ or more.
GaInP which is highly doped with Se, which has a property of growing by embedding the irregularities in the relaxation buffer layer itself, which is a source of generating cross-hatch irregularities related to lattice irregularity, is characterized by being InP. Is used, the effect of alleviating the lattice irregularity and the effect of flattening the surface are also provided, so that the total thickness of the grown layer can be reduced. Thereby, high temperature, high output and stable operation 63
A red semiconductor laser having a wavelength of 5 nm or 650 nm or the like, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode having high luminous efficiency, and the like can be provided.

According to a nineteenth aspect of the present invention, in the semiconductor light emitting device according to any one of the first to eighteenth aspects, the heterojunction is formed by metal organic chemical vapor deposition.
(MOCVD) or molecular beam epitaxy (MBE). AlG
The aInP (As) -based material has a large segregation coefficient of Al from a solution to a solid phase, and it is difficult to grow a liquid layer from the viewpoint of composition control. In addition, vapor phase epitaxy (VPE) by halogen transport method
However, there is a problem that the raw material AlCl corrodes the quartz reaction tube, which is difficult. On the other hand, metal organic chemical vapor deposition (MOCV
D) or molecular beam epitaxy (MBE) is a highly non-equilibrium growth method, and the growth is governed by the group III raw material supply rule, so that these materials are extremely effective and can be easily grown. . Accordingly, it is possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably at a high temperature, a high output, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

According to a twentieth aspect of the present invention, in the semiconductor light emitting device according to the nineteenth aspect, the relaxation buffer layer is grown by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). Because
Growth can be carried out continuously with the same device as the crystal growth device at the heterojunction, and only one device is required, which is easy and has a cost advantage. As a result, high temperature, high output,
It is possible to provide a red semiconductor laser in the 635 nm, 650 nm band or the like that operates stably, a visible semiconductor laser oscillating at a wavelength shorter than 600 nm at room temperature, a visible light emitting diode with high luminous efficiency, and the like.

[Brief description of the drawings]

FIG. 1 is a diagram showing a relationship between a lattice constant and band gap energy.

FIG. 2 is a diagram showing a configuration example of a semiconductor light emitting device according to the present invention.

FIG. 3 is a diagram showing a configuration example of a semiconductor light emitting device according to the present invention.

FIG. 4 is a diagram showing a configuration example of a semiconductor light emitting device according to the present invention.

FIG. 5 is a diagram showing a basic configuration of a semiconductor light emitting device according to Examples 1 to 7 of the present invention.

FIG. 6 is a diagram showing a superlattice buffer layer of Example 4.

FIG. 7 is a view showing an active layer of Examples 6 and 7;

FIG. 8 is a diagram showing a configuration of a semiconductor light emitting device according to Example 8 of the present invention.

FIG. 9 is a diagram showing a configuration of a semiconductor light emitting device according to a ninth embodiment of the present invention.

FIG. 10 is a diagram showing a configuration of a semiconductor light emitting device according to Example 10 of the present invention.

FIG. 11 shows 2 ° off from the (100) plane in the [110] direction.
And AlI on GaP _0.4 As _0.6 epi substrate
It is a figure which shows the surface Nomarski (surface morphology) photograph of nPAs.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Active layer 3 Cladding layer 4 Heterojunction 5 Optical guide layer 6 Relaxation buffer layer 11 Semiconductor substrate 12 Graded buffer layer, super lattice buffer
Layer, low-temperature buffer layer 13 uniform composition layer 14, 18 clad layer 15, 17 light guide layer 16 active layer 19 cap layer 20 contact layer 21 SiO₂  22 p-side electrode 23 n-side electrode 11 semiconductor substrate 12 graded buffer layer, super lattice buffer
Layer, low-temperature buffer layer 13 uniform composition layer 14, 18 clad layer 15, 17 light guide layer 16 active layer 19 cap layer 20 contact layer 21 SiO₂  22 p-side electrode 23 n-side electrode 11 semiconductor substrate 12 graded buffer layer, super lattice buffer
Layer, low-temperature buffer layer 13 uniform composition layer 14, 18 clad layer 15, 17 light guide layer 16 active layer 19 cap layer 20 contact layer 21 SiO₂  22 p-side electrode 23 n-side electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Naoto Shakuya 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. 5F073 AA45 AA55 AA73 AA74 CA13 CA20 CB02 CB07 CB08 CB09 EA06 EA07 EA22 EA23 EA24 EA28

Claims (20)

[Claims] In a semiconductor light emitting device in which a heterojunction having an active layer for generating light and a cladding layer for confining light is formed on a semiconductor substrate, the active layer is (Al _x
Ga _1−x ) _α In _{1−α Pt} As _1−t (0 ≦ x <1,
0 <consists α ≦ 1,0 ≦ t ≦ 1) , the cladding layer containing Al having a lattice constant between the band gap than the active layer is largely GaP and _{GaAs (Al y Ga 1-y} ) β
In _{1 −β Pv} As _1−v (0 <y ≦ 1, 0.5 <β <
1, 0 <v ≦ 1). 2. An active layer for generating light on a semiconductor substrate.
Heterojunction with cladding layer to confine light is formed
In the semiconductor light emitting device described, the active layer is (Al_x
Ga_1-x)_αIn_1-αP_tAs_1-t(0 ≦ x <1,
0 <α ≦ 1, 0 ≦ t ≦ 1)
The pad layer has a larger band gap than the active layer,
Including Al having a lattice constant between GaAs (Al
_yGa _1-y)_βIn_1-βP_vAs_1-v(0 <y ≦
1, 0.5 <β <1, 0 <v ≦ 1), and the active layer
Band gap larger than the active layer between the cladding layer
Smaller than the cladding layer (Al_zGa_1-z)_γIn
_1-γP_uAs_1-u(0 ≦ z <1, 0.5 <γ <1,
0 <u ≦ 1).
Semiconductor light emitting device. 3. An active layer for generating light on a semiconductor substrate.
Heterojunction with cladding layer to confine light is formed
In the semiconductor light emitting device described above, the active layer and the well layer
It has a quantum well structure composed of a barrier layer and a well layer.
(Al_x1Ga _1-x1)_α1In_1-α1P_t1As
_1-t1(0 ≦ x1 <1, 0 <α1 ≦ 1, 0 ≦ t1 ≦ 1)
And the barrier layer is made of (Al_x2Ga_1-x2)_α2In
_1-α2P _t2As_1-t2(0 ≦ x2 <1, 0.5 <
α2 <1, 0 ≦ t2 ≦ 1), and the cladding layer is active
Layer has a larger bandgap than GaP and GaAs.
Containing Al having a lattice constant between (Al_yGa_1-y)
_βIn_1-βP_vAs_1-v(0 <y ≦ 1, 0.5 <β <
1, 0 <v ≦ 1), between the active layer and the cladding layer.
In addition, the band gap is larger than the active layer and
Small (Al_zGa_{1- z})_γIn_1-γP_uAs_1-u
(0 ≦ z <1, 0.5 <γ <1, 0 <u ≦ 1)
Semiconductor light emitting device having a guide layer
Child. 4. The semiconductor light emitting device according to claim 1, wherein the active layer contains As. (Al _x Ga _1−x ) _α In _{1−α Pt} As
_1-t (0 ≦ x <1, 0 <α1 ≦ 1, 0 ≦ t ≦ 1). 5. The semiconductor light-emitting device according to claim 2, wherein the light guide layer is formed of a Ga _γ In _{1-γ Pu} As _1-u (0.5 <) containing no Al. γ <
1, 0 <u ≦ 1). 6. The method according to any one of claims 1 to 5, wherein
In the above described semiconductor light emitting device, the cladding layer contains As.
(Al_yGa_1-y)_βIn_1-βP _vAs
_1-v(0 <y ≦ 1, 0.5 <β <1, 0 <v <1)
A semiconductor light emitting device, comprising: 7. The semiconductor light emitting device according to claim 2, wherein a lattice constant of the well layer is:
A semiconductor light-emitting device having a compression strain larger than a cladding layer. 8. The semiconductor light emitting device according to claim 1, wherein the semiconductor substrate is GaPA.
and a heterojunction crystal grown on the semiconductor substrate. 9. The semiconductor light emitting device according to claim 1, wherein the semiconductor substrate is GaAs.
A semiconductor light emitting device comprising GaP, wherein a heterojunction is crystal-grown between a semiconductor substrate and a cladding layer via a buffer layer for relaxing lattice mismatch between the two. 10. The semiconductor light emitting device according to claim 9, wherein the relaxation buffer layer comprises a graded layer whose lattice constant gradually changes from the lattice constant of the semiconductor substrate in the growth direction and approaches the lattice constant of the cladding layer. A semiconductor light emitting device characterized by the above-mentioned. 11. The semiconductor light emitting device according to claim 9, wherein the relaxation buffer layer has a strained superlattice structure in which at least two kinds of materials having different lattice constants are alternately stacked. 12. The semiconductor light-emitting device according to claim 9, wherein the buffer layer comprises a low-temperature buffer layer grown at a temperature lower than the growth temperature of the clad layer. 13. The semiconductor light emitting device according to claim 9, wherein the relaxation buffer layer is made of GaInP or GaPAs. 14. The semiconductor light emitting device according to claim 8, wherein the plane orientation of the semiconductor substrate is a plane inclined from 0 ° to 54.7 ° in the [011] direction from the (100) plane. Alternatively, a semiconductor light emitting device characterized by a surface inclined from 10 ° to 54.7 ° in the [0-11] direction from the (100) plane, or a plane equivalent thereto. 15. The semiconductor light emitting device according to claim 8, wherein the surface of the GaPAs substrate is flattened by mechanical polishing before the crystal growth of the heterojunction, or after the growth of the relaxation buffer layer. A semiconductor light emitting device, wherein the surface before the crystal growth of the heterojunction is planarized by mechanical polishing. 16. The semiconductor light emitting device according to claim 8, further comprising a layer between the semiconductor substrate and the heterojunction, the upper surface of the interface of the layer being flatter than the lower surface (substrate side). A semiconductor light emitting device characterized by the above-mentioned. 17. The semiconductor light emitting device according to claim 16, wherein the upper surface of the interface of the layer is flatter than the lower surface (substrate side), and Ga doped with Se to 5 × 10 ¹⁸ cm ⁻³ or more.
A semiconductor light emitting device, which is InP. 18. The semiconductor light emitting device according to claim 9, wherein the relaxation buffer layer is GaInP doped with Se to 5 × 10 ¹⁸ cm ⁻³ or more. 19. The semiconductor light emitting device according to claim 1, wherein the heterojunction is grown by metal organic chemical vapor deposition or molecular beam epitaxy. Semiconductor light emitting device. 20. The semiconductor light emitting device according to claim 19, wherein the relaxation buffer layer is grown by a metal organic chemical vapor deposition method or a molecular beam epitaxy method.