JP7462902B2 - Light emitting device, projector, and method for manufacturing light emitting device - Google Patents

Description

The present invention relates to a light-emitting device, a projector, and a method for manufacturing a light-emitting device.

Semiconductor lasers are expected to be the next generation of high-brightness light sources. In particular, semiconductor lasers with nanostructures such as nanocolumns, nanowires, nanorods, and nanopillars are expected to realize light-emitting devices that can emit high-output light at a narrow radiation angle due to the effect of photonic crystals.

For example, Patent Document 1 discloses a light emitting device having a columnar portion including a first semiconductor layer, a second semiconductor layer having a different conductivity type from the first semiconductor layer, and an active layer provided between the first and second semiconductor layers, and a low refractive index portion having a lower refractive index than the second semiconductor layer is provided in a recess provided in the second semiconductor layer. In the light emitting device of Patent Document 1, the average refractive index in the in-plane direction is lowered by providing a recess in the second semiconductor layer, thereby reducing leakage of light generated in the active layer to the electrode side.

JP 2019-083232 A

However, in the light-emitting device of Patent Document 1, the recesses are arranged randomly, which causes variation in the amount of current injected into each columnar portion. For example, the amount of current injected into a columnar portion where the recesses are arranged densely is less than the amount of current injected into a columnar portion where the recesses are arranged sparsely.

One aspect of the light emitting device according to the present invention is
A substrate;
a laminate provided on the substrate and having a plurality of columnar portions;
having
The laminate comprises:
A first semiconductor layer;
A second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
a light emitting layer provided between the first semiconductor layer and the second semiconductor layer;
having
the first semiconductor layer and the light emitting layer constitute the columnar portion,
the first semiconductor layer is provided between the substrate and the light emitting layer,
The second semiconductor layer is provided with a recess.
a low refractive index portion having a refractive index lower than that of the second semiconductor layer is provided in the recess;
The recesses and the columnar portions are provided in one-to-one correspondence.

In one embodiment of the light emitting device,
In a plan view, a center of the recess and a center of the columnar portion may overlap.

In one embodiment of the light emitting device,
The second semiconductor layer may be a single layer provided across a plurality of the columnar portions.

In one embodiment of the light emitting device,
The second semiconductor layer may form the columnar portion.

In one embodiment of the light emitting device,
The low refractive index portion may be a void.

One aspect of the projector according to the present invention is
The light emitting device includes the light emitting device.

One aspect of the method for producing a light emitting device according to the present invention includes:
forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing AlGaN on the light emitting layer to form a second semiconductor layer having a first portion and a second portion surrounding the first portion in a plan view and having a higher Al composition ratio than the first portion, the second semiconductor layer having a different conductivity type from the first semiconductor layer;
etching the first portion of the second semiconductor layer to form a recess in the second semiconductor layer;
has.

One aspect of the method for producing a light emitting device according to the present invention includes:
forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing GaN on the light emitting layer to form a columnar GaN layer;
epitaxially growing AlGaN on the GaN layer to form a second semiconductor layer having an AlGaN layer covering the GaN layer and a conductivity type different from that of the first semiconductor layer;
etching the AlGaN layer to expose the GaN layer, and etching the exposed GaN layer to form a recess in the second semiconductor layer;
has.

One aspect of the method for producing a light emitting device according to the present invention includes:
forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing GaN on the light emitting layer to form a second semiconductor layer having a first portion and a second portion surrounding the first portion in a plan view and having better crystallinity than the first portion, the second semiconductor layer having a different conductivity type from the first semiconductor layer;
etching the first portion of the second semiconductor layer to form a recess in the second semiconductor layer;
has.

One aspect of the method for producing a light emitting device according to the present invention includes:
forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing GaN on the light emitting layer to form a second semiconductor layer having a first portion with N polarity and a second portion with Ga polarity surrounding the first portion in a plan view, the second semiconductor layer having a different conductivity type from the first semiconductor layer;
etching the first portion of the second semiconductor layer to form a recess in the second semiconductor layer;
has.

1 is a cross-sectional view illustrating a schematic configuration of a light emitting device according to a first embodiment. FIG. 1 is a plan view illustrating a light emitting device according to a first embodiment. 4 is a flowchart showing an example of a method for manufacturing the light emitting device according to the first embodiment. 3A to 3C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the first embodiment. 3A to 3C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the first embodiment. 3A to 3C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the first embodiment. FIG. 11 is a cross-sectional view illustrating a light emitting device according to a modified example of the first embodiment. FIG. 11 is a plan view illustrating a light emitting device according to a modified example of the first embodiment. 7A to 7C are cross-sectional views each showing a schematic process for manufacturing a light emitting device according to a modified example of the first embodiment. FIG. 11 is a cross-sectional view illustrating a light emitting device according to a second embodiment. 10 is a flowchart showing an example of a method for manufacturing a light emitting device according to a second embodiment. 10A to 10C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the second embodiment. 10A to 10C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the second embodiment. 10A to 10C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the second embodiment. FIG. 11 is a cross-sectional view illustrating a light emitting device according to a third embodiment. 13 is a flowchart showing an example of a method for manufacturing a light emitting device according to the third embodiment. 11A to 11C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the third embodiment. 11A to 11C are cross-sectional views each showing a schematic manufacturing process of the light emitting device according to the third embodiment. FIG. 13 is a cross-sectional view illustrating a light emitting device according to a fourth embodiment. 13 is a flowchart showing an example of a method for manufacturing a light emitting device according to a fourth embodiment. 10A to 10C are cross-sectional views each showing a schematic manufacturing process of a light emitting device according to a fourth embodiment. 10A to 10C are cross-sectional views each showing a schematic manufacturing process of a light emitting device according to a fourth embodiment. FIG. 13 is a diagram illustrating a projector according to a fifth embodiment.

Below, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

1. First embodiment 1.1. Light emitting device First, the light emitting device according to the first embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view that shows a schematic of the light emitting device 100 according to the first embodiment. Fig. 2 is a plan view that shows a schematic of the light emitting device 100 according to the first embodiment. For convenience, Fig. 2 shows only the second semiconductor layer 36. Fig. 1 is a cross-sectional view taken along line II in Fig. 2.

As shown in FIG. 1, the light-emitting device 100 has a substrate 10, a laminate 20, a first electrode 50, and a second electrode 52.

The substrate 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, etc.

The laminate 20 is provided on the substrate 10. The laminate 20 has a buffer layer 22, a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36.

The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is, for example, S
The buffer layer 22 is an n-type GaN layer doped with i. A mask layer 60 for forming the columnar section 30 is provided on the buffer layer 22. The mask layer 60 is, for example, a titanium layer, a titanium oxide layer, a silicon oxide layer, an aluminum oxide layer, or the like.

In this specification, in the stacking direction of the laminate 20 (hereinafter also simply referred to as the "stacking direction"), when the light emitting layer 34 is used as a reference, the direction from the light emitting layer 34 toward the second semiconductor layer 36 is described as "up" and the direction from the light emitting layer 34 toward the first semiconductor layer 32 is described as "down." In addition, the "stacking direction of the laminate" refers to the stacking direction of the first semiconductor layer 32 and the light emitting layer 34.

The first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 constitute a columnar section 30. The laminate 20 has a plurality of columnar sections 30. The columnar sections 30 are provided on the buffer layer 22. The columnar sections 30 have a columnar shape that protrudes upward from the buffer layer 22. The columnar sections 30 are also called, for example, nanocolumns, nanowires, nanorods, and nanopillars. The planar shape of the columnar sections 30 is, for example, a polygon, a circle, or the like. In the example shown in FIG. 2, the planar shape of the columnar sections 30 is a hexagon.

The diameter of the columnar section 30 is, for example, 50 nm or more and 500 nm or less. By making the diameter of the columnar section 30 500 nm or less, a light-emitting layer 34 of high quality crystals can be obtained, and the distortion inherent in the light-emitting layer 34 can be reduced. This allows the light generated in the light-emitting layer 34 to be amplified with high efficiency. The diameters of the multiple columnar sections 30 are, for example, equal to each other.

The "diameter of the columnar portion" refers to the diameter when the planar shape of the columnar portion 30 is a circle, and refers to the diameter of the smallest inclusive circle when the planar shape of the columnar portion 30 is not a circle. For example, when the planar shape of the columnar portion 30 is a polygon, the diameter of the columnar portion 30 refers to the diameter of the smallest circle that contains the polygon, and when the planar shape of the columnar portion 30 is an ellipse, the diameter of the smallest circle that contains the ellipse.

A plurality of columnar sections 30 are provided. The interval between adjacent columnar sections 30 is, for example, 1 nm or more and 500 nm or less. The plurality of columnar sections 30 are arranged at a predetermined pitch in a predetermined direction in a plan view seen from the stacking direction (hereinafter also simply referred to as "in a plan view"). The plurality of columnar sections 30 are arranged in a triangular lattice pattern. The arrangement of the plurality of columnar sections 30 is not particularly limited, and may be arranged in a square lattice pattern. The plurality of columnar sections 30 can exhibit the effect of a photonic crystal.

The "pitch of the columnar portion" is the distance between the centers of adjacent columnar portions 30 along a specified direction. The "center of the columnar portion" refers to the center of the circle when the planar shape of the columnar portion 30 is a circle, and to the center of the smallest inclusive circle when the planar shape of the columnar portion 30 is not a circle. For example, when the planar shape of the columnar portion 30 is a polygon, the center of the smallest circle that contains the polygon within itself, and when the planar shape of the columnar portion 30 is an ellipse, the center of the smallest circle that contains the ellipse within itself.

The columnar section 30 has a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36.

The first semiconductor layer 32 is provided on the buffer layer 22. The first semiconductor layer 32 is provided between the substrate 10 and the light emitting layer 34. The first semiconductor layer 32 is an n-type semiconductor layer. The first semiconductor layer 32 is, for example, an n-type GaN layer doped with Si.

The light emitting layer 34 is provided on the first semiconductor layer 32. The light emitting layer 34 is provided between the first semiconductor layer 32 and the second semiconductor layer 36. The light emitting layer 34 generates light when a current is injected into it. The light emitting layer 34 has a multiple quantum well structure in which a quantum well structure made of an i-type GaN layer not doped with impurities and an i-type InGaN layer are stacked, for example.

The second semiconductor layer 36 is provided on the light emitting layer 34. The second semiconductor layer 36 is a layer of a different conductivity type from the first semiconductor layer 32. The second semiconductor layer 36 is a p-type semiconductor layer. The second semiconductor layer 36 is, for example, a p-type AlGaN layer doped with Mg. The first semiconductor layer 32 and the second semiconductor layer 36 are cladding layers that have the function of confining light in the light emitting layer 34.

The second semiconductor layer 36 has a recess 40. The recess 40 is a space defined by the surface of the second semiconductor layer 36. The recess 40 has an opening in the upper surface of the second semiconductor layer 36. The upper surface of the second semiconductor layer 36 is the surface of the second semiconductor layer 36 opposite the substrate 10 side. In the illustrated example, the upper surface of the second semiconductor layer 36 is in contact with the second electrode 52.

As shown in Figures 1 and 2, the recesses 40 and the columnar portions 30 are provided in a one-to-one correspondence. That is, one recess 40 is provided for one columnar portion 30. The columnar portions 30 are arranged at a predetermined pitch in a predetermined direction, and the recesses 40, like the columnar portions 30, are also arranged at a predetermined pitch in a predetermined direction. In the illustrated example, the columnar portions 30 are arranged in a triangular lattice pattern, and the recesses 40 are also arranged in a triangular lattice pattern.

As shown in FIG. 2, in a plan view, the center of the recess 40 and the columnar portion 30 overlap. That is, in a plan view, the center of the recess 40 is located inside the outer edge of the columnar portion 30. In the example shown in FIG. 2, the center of the recess 40 and the center of the columnar portion 30 overlap. That is, in a plan view, the position of the center of the recess 40 and the position of the center of the columnar portion 30 coincide with each other.

Note that the "center of the recess" refers to the center of a circle when the planar shape of the recess 40 is a circle, and refers to the center of the smallest inclusive circle when the planar shape of the recess 40 is not a circle. For example, when the planar shape of the recess 40 is a polygon, the center of the smallest circle that contains the polygon within itself, and when the planar shape of the recess 40 is an ellipse, the center of the smallest circle that contains the ellipse within itself.

The depth of the recess 40, i.e., the size of the recess 40 in the stacking direction, is smaller than the thickness of the second semiconductor layer 36. Therefore, the upper surface of the light-emitting layer 34 is covered by the second semiconductor layer 36 and is not exposed by the recess 40.

The planar shape of the recess 40 is a circle, as shown in FIG. 2. That is, the shape of the opening of the recess 40 is a circle. The planar shape of the recess 40 is not particularly limited, and may be a polygon, an ellipse, or the like. The planar shape of the recess 40 is the shape of the recess 40 when viewed from the stacking direction. The diameter of the opening of the recess 40 is smaller than the diameter of the columnar portion 30.

The recess 40 is provided with a low-refractive index portion 42 having a lower refractive index than the second semiconductor layer 36. The low-refractive index portion 42 is, for example, a void, i.e., air. The low-refractive index portion 42 is not limited to a void, and may be made of any low-refractive material having a lower refractive index than the second semiconductor layer 36. The material of the low-refractive index portion 42 is, for example, AlGaN, AlN, InAlN, silicon oxide, silicon nitride, polyimide, etc.

In the light emitting device 100, the recesses 40 and the columnar portions 30 are provided in a one-to-one relationship, and therefore the low refractive index portions 42 and the columnar portions 30 are provided in a one-to-one relationship. In addition, in a plan view, the center of the recesses 40 and the columnar portions 30 overlap, and therefore the center of the low refractive index portions 42 and the columnar portions 30 overlap.

The average refractive index in the in-plane direction of the portion of the second semiconductor layer 36 where the low refractive index portion 42 is provided is lower than the average refractive index in the in-plane direction of the portion of the second semiconductor layer 36 where the low refractive index portion 42 is not provided. Since the low refractive index portion 42 is provided near the second electrode 52 of the second semiconductor layer 36, the average refractive index in the in-plane direction near the second electrode 52 of the second semiconductor layer 36 can be reduced.

The space between adjacent columnar sections 30 is, for example, a gap. A light propagation layer may be provided between adjacent columnar sections 30. The light propagation layer is, for example, a silicon oxide layer, an aluminum oxide layer, a titanium oxide layer, or the like. The light generated in the light-emitting layer 34 can propagate through the multiple columnar sections 30 in a direction perpendicular to the stacking direction through the gap or the light propagation layer.

The first electrode 50 is provided on the buffer layer 22. The buffer layer 22 may be in ohmic contact with the first electrode 50. The first electrode 50 is electrically connected to the first semiconductor layer 32. In the illustrated example, the first electrode 50 is electrically connected to the first semiconductor layer 32 via the buffer layer 22. The first electrode 50 is one of the electrodes for injecting a current into the light-emitting layer 34. As the first electrode 50, for example, a layer formed by laminating a Cr layer, a Ni layer, and an Au layer in this order from the buffer layer 22 side is used.

The second electrode 52 is provided on the side of the laminate 20 opposite the substrate 10 side. In the illustrated example, the second electrode 52 is provided on the second semiconductor layer 36 and on the recess 40. The second electrode 52 is not provided in the recess 40. The second electrode 52 is not provided on the surface of the second semiconductor layer 36 that defines the recess 40.

The second electrode 52 is electrically connected to the second semiconductor layer 36. The second electrode 52 is the other electrode for injecting a current into the light-emitting layer 34. For example, ITO (indium tin oxide) is used as the second electrode 52. The film thickness of the second electrode 52 is, for example, 100 nm or more and 300 nm or less.

Although not shown, a contact layer may be provided between the second semiconductor layer 36 and the second electrode 52. The contact layer is, for example, a p-type GaN layer. The contact layer may be provided for each columnar section 30 to form the columnar section 30, or may be a single layer provided across multiple columnar sections 30.

In the light-emitting device 100, a pin diode is formed by the p-type second semiconductor layer 36, the light-emitting layer 34, and the n-type first semiconductor layer 32. In the light-emitting device 100, when a forward bias voltage of the pin diode is applied between the first electrode 50 and the second electrode 52, a current is injected into the light-emitting layer 34, and electrons and holes recombine in the light-emitting layer 34. This recombination causes light emission. The light generated in the light-emitting layer 34 propagates in a direction perpendicular to the stacking direction by the first semiconductor layer 32 and the second semiconductor layer 36, forms a standing wave due to the effect of the photonic crystal of the multiple columnar parts 30, and receives gain in the light-emitting layer 34 to oscillate as a laser. Then, the light-emitting device 100 emits the +1st order diffracted light and the -1st order diffracted light as laser light in the stacking direction.

In the light emitting device 100, the low refractive index portion 42 is provided in the second semiconductor layer 36, thereby making it possible to lower the average refractive index in the in-plane direction of the second semiconductor layer 36 near the second electrode 52. Therefore, in the light emitting device 100, the effect of confining light near the light emitting layer 34 can be enhanced, and the leakage of light generated in the light emitting layer 34 to the second electrode 52 side can be reduced. Therefore, in the light emitting device 100, the absorption of light by the second electrode 52 can be reduced, and the loss of light by the second electrode 52 can be reduced.

Although the above describes an InGaN-based light emitting layer 34, various materials capable of emitting light when a current is injected depending on the wavelength of the emitted light can be used as the light emitting layer 34. For example, semiconductor materials such as AlGaN-based, AlGaAs-based, InGaAs-based, InGaAsP-based, InP-based, GaP-based, and AlGaP-based materials can be used.

The light emitting device 100 can achieve the following effects, for example:

In the light-emitting device 100, the recesses 40 and the columnar portions 30 are provided in one-to-one correspondence, and in a plan view, the center of the recesses 40 and the columnar portions 30 overlap. Therefore, in the light-emitting device 100, the variation in the amount of current injected into each columnar portion 30 can be reduced compared to when the recesses 40 are provided randomly.

In the light-emitting device 100, the center of the recess 40 and the center of the columnar portion 30 overlap in a plan view. Therefore, in the light-emitting device 100, the variation in the amount of current injected into each columnar portion 30 can be reduced compared to when the center of the recess 40 and the center of the columnar portion 30 are misaligned.

In the light emitting device 100, the recess 40 is provided with a low refractive index portion 42, which is a void. Therefore, in the light emitting device 100, the average refractive index in the in-plane direction near the second electrode 52 of the second semiconductor layer 36 can be reduced compared to when the low refractive index portion 42 is not a void. Therefore, the absorption of light by the second electrode 52 can be further reduced.

1.2. Manufacturing Method of the Light-Emitting Device Next, a manufacturing method of the light-emitting device 100 according to the first embodiment will be described with reference to the drawings. Fig. 3 is a flow chart showing an example of a manufacturing method of the light-emitting device 100 according to the first embodiment. Figs. 4 to 6 are cross-sectional views that typically show the manufacturing process of the light-emitting device 100 according to the first embodiment.

1.2.1. Formation of columnar crystals (S100)
As shown in FIG. 4, a first semiconductor layer 32 and a light emitting layer 34 are formed in a columnar shape on a substrate 10 to form a plurality of columnar crystals 3 .

Specifically, first, the buffer layer 22 is epitaxially grown on the substrate 10. Examples of methods for epitaxial growth include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

Next, a mask layer 60 is formed on the buffer layer 22. The mask layer 60 can be formed, for example, by forming openings periodically in a film formed on the buffer layer 22 by a sputtering method or the like.

Next, the first semiconductor layer 32 and the light emitting layer 34 are epitaxially grown on the buffer layer 22 using the mask layer 60 as a mask. Examples of the epitaxial growth method include MOCVD and MBE. As a result, the first semiconductor layer 32 and the light emitting layer 34 grow in a columnar shape, and a plurality of columnar crystals 3 are formed.

1.2.2. Formation of second semiconductor layer (S102)
As shown in Fig. 5, AlGaN is epitaxially grown on the light emitting layer 34 to form a second semiconductor layer 36 having a first portion 36a and a second portion 36b. The first portion 36a is formed in the center of the columnar section 30 in a plan view. The second portion 36b surrounds the first portion 36a in a plan view. The second portion 36b constitutes a sidewall portion of the columnar section 30. The Al composition ratio of the second portion 36b is higher than the Al composition ratio of the first portion 36a. For example, the second portion 36b may be AlGaN, and the first portion 36a may be GaN.

In this process, first, AlGaN is epitaxially grown on the light-emitting layer 34. Examples of methods for epitaxial growth include MOCVD and MBE. By controlling the conditions for epitaxially growing AlGaN, Al segregates to the sidewall of the columnar section 30, and the Al composition ratio of the sidewall of the columnar section 30 becomes higher than the Al composition ratio of the center of the columnar section 30. As a result, a second semiconductor layer 36 having a first portion 36a and a second portion 36b is formed.

This process forms a columnar section 30 having a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36.

1.2.3. Formation of recesses (S104)
As shown in FIG. 6, the first portion 36a of the second semiconductor layer 36 is etched to form a recess 40 in the second semiconductor layer 36.

Generally, the higher the Al composition ratio of AlGaN, the lower the etching rate. Therefore, the etching rate of the second portion 36b is lower than the etching rate of the first portion 36a. In this process, the recess 40 is formed by selectively etching the first portion 36a by utilizing the difference in etching rate between the first portion 36a and the second portion 36b.

The second semiconductor layer 36 is etched from above by anisotropic etching using, for example, an ICP (Inductively Coupled Plasma) device. This allows the first portion 36a to be selectively etched while preventing the first semiconductor layer 32 and the light-emitting layer 34 from being etched.

In this process, the recess 40 is formed by etching the first portion 36a of the second semiconductor layer 36, so that the recess 40 and the columnar portion 30 can be in one-to-one correspondence. Furthermore, the center position of the recess 40 can be made to coincide with the center position of the columnar portion 30 in a plan view.

1.2.4. Formation of electrodes (S106)
As shown in FIG. 1, a first electrode 50 is formed on the buffer layer 22, and a second electrode 52 is formed on the second semiconductor layer 36. The first electrode 50 and the second electrode 52 are formed by, for example, a vacuum deposition method, a sputtering method, or the like. For example, when the second electrode 52 is formed by a vacuum deposition method, deposition is performed from an oblique direction with respect to the stacking direction. This can prevent the electrode material from entering the recess 40. Also, for example, when the second electrode 52 is formed by a sputtering method, sputtering deposition is performed from an oblique direction with respect to the stacking direction, so that the electrode material can be prevented from entering the recess 40.

The above steps allow the light emitting device 100 to be manufactured.

In the above, the case where the low refractive index portion 42 is a gap (air) has been described. However, if the material of the low refractive index portion 42 is AlGaN, AlN, InAlN, silicon oxide, silicon nitride, polyimide, or the like, the low refractive index portion 42 is provided in the recess 40 after step S104 of forming the recess 40. The low refractive index portion 42 can be formed by embedding the material constituting the low refractive index portion 42 in the recess 40 by, for example, the MOCVD method, the MBE method, the CVD method, or the like. After the low refractive index portion 42 is formed in the recess 40, the second electrode 52 is formed. This makes it possible to prevent the electrode material from entering the recess 40.

The manufacturing method for the light emitting device 100 can achieve, for example, the following effects:

The manufacturing method of the light emitting device 100 includes a step S100 of forming a first semiconductor layer 32 and a light emitting layer 34 in a columnar shape on the substrate 10 to form a plurality of columnar crystals 3; a step S102 of epitaxially growing AlGaN on the light emitting layer 34 to form a second semiconductor layer 36 having a first portion 36a and a second portion 36b that surrounds the first portion 36a in a plan view and has a higher Al composition ratio than the first portion 36a; and a step of etching the first portion 36a of the second semiconductor layer 36 to form a recess 40 in the second semiconductor layer 36.

In this manufacturing method for the light emitting device 100, by utilizing the difference in etching rate due to the difference in the Al composition ratio in AlGaN, it is possible to easily manufacture a light emitting device in which the recesses 40 and the columnar sections 30 correspond one-to-one. In other words, it is possible to easily manufacture a light emitting device that can reduce the variation in the amount of current injected into each columnar section 30.

For example, when forming the first semiconductor layer 32, the light-emitting layer 34, and the second semiconductor layer 36 into a columnar shape and then forming a recess 40 in the second semiconductor layer 36 by a patterning technique such as electron beam lithography or photolithography, in order to achieve a one-to-one correspondence between the columnar portion 30 and the recess 40, it is necessary to align the positional relationship between the columnar portion 30 and the recess 40 with high precision. In contrast, the manufacturing method for the light-emitting device 100 does not require such alignment, and the recess 40 can be easily formed with high precision.

1.3. Modifications 1.3.1. Light-emitting device Next, a light-emitting device according to a modification of the first embodiment will be described with reference to the drawings. Fig. 7 is a cross-sectional view that shows a light-emitting device 110 according to a modification of the first embodiment. Fig. 8 is a plan view that shows a light-emitting device 110 according to a modification of the first embodiment. For convenience, Fig. 8 shows only the second semiconductor layer 36. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 8.

In the following description of the light-emitting device 110 according to a modified example of the first embodiment, components having the same functions as the components of the light-emitting device 100 according to the first embodiment described above are given the same reference numerals, and detailed descriptions thereof will be omitted.

In the light emitting device 100 described above, as shown in Figs. 1 and 2, the second semiconductor layer 36 constitutes the columnar section 30. In contrast, in the light emitting device 110, as shown in Figs. 7 and 8, the second semiconductor layer 36 is a single layer provided across multiple columnar sections 30.

In the example shown in FIG. 7, the lower portion 360 of the second semiconductor layer 36 constitutes a columnar portion 30, and the upper portion 362 of the second semiconductor layer 36 does not constitute a columnar portion 30. The upper portion 362 of the second semiconductor layer 36 is not columnar, but constitutes a single layer that is provided across multiple columnar portions 30.

The upper portion 362 of the second semiconductor layer 36 is the portion of the second semiconductor layer 36 on the second electrode 52 side, and in the illustrated example, is in contact with the second electrode 52. The lower portion 360 of the second semiconductor layer 36 is the portion of the second semiconductor layer 36 on the light emitting layer 34 side, and in the illustrated example, is in contact with the light emitting layer 34.

In the light emitting device 110, like the light emitting device 100, the recesses 40 and the columnar portions 30 are provided in a one-to-one correspondence. That is, one recess 40 is provided for one columnar portion 30. Also, in the light emitting device 110, like the light emitting device 100, the center of the recess 40 and the columnar portion 30 overlap in a plan view. In the example shown in FIG. 8, the center of the recess 40 and the center of the columnar portion 30 overlap.

In the above, the recess 40 is provided in the upper portion 362 and the lower portion 360 of the second semiconductor layer 36, but the recess 40 may be provided only in the upper portion 362 of the second semiconductor layer 36. In other words, the recess 40 is provided in a portion of the second semiconductor layer 36 that spans multiple columnar portions 30, and does not have to be provided in the columnar portions 30. Even in this case, the recess 40 and the columnar portions 30 are provided in a one-to-one correspondence, and the center of the recess 40 overlaps with the columnar portion 30 in a planar view.

The light emitting device 110 can achieve the same effect as the light emitting device 100 described above. In addition, in the light emitting device 110, the second semiconductor layer 36 is a single layer provided across multiple columnar sections 30, so the contact area between the second electrode 52 and the second semiconductor layer 36 can be increased and the electrical resistance can be reduced compared to when the second semiconductor layer 36 does not span multiple columnar sections 30.

1.3.2 Manufacturing Method of Light-Emitting Device The manufacturing method of the light-emitting device 110 differs from the manufacturing method of the light-emitting device 100 in that in step S102 of forming the second semiconductor layer 36 described above, the second semiconductor layer 36 is formed as one layer provided across a plurality of columnar sections 30. Below, the points that differ from the manufacturing method of the light-emitting device 100 described above will be described, and a description of the similar points will be omitted.

Figure 9 is a cross-sectional view that shows a schematic diagram of the manufacturing process of the light-emitting device 110.

Step S100 for forming the columnar crystals 3 is performed in the same manner as in the manufacturing method of the light emitting device 100 described above.

In step S102 of forming the second semiconductor layer 36, AlGaN is epitaxially grown on the light emitting layer 34 to form the second semiconductor layer 36 having a first portion 36a and a second portion 36b. At this time, as shown in FIG. 9, the epitaxial growth is performed under conditions in which the AlGaN grows not only in the stacking direction but also in the in-plane direction. For example, during epitaxial growth, the AlGaN can be grown in the in-plane direction by controlling the gas supply amount, growth temperature, etc. As a result, the distance between adjacent columnar portions 30 decreases as the AlGaN grows, and the adjacent columnar portions 30 are eventually connected.

As a result, the upper portion 362 of the second semiconductor layer 36 can be formed as a single layer spanning multiple columnar sections 30.

In this process, a second semiconductor layer 36 can be formed that has a first portion 36a and a second portion 36b and is formed as a single layer spanning multiple columnar sections 30.

The process S104 of etching the second semiconductor layer 36 and the process S106 of forming the first electrode 50 and the second electrode 52 are performed in the same manner as in the manufacturing method of the light emitting device 100 described above.

The above steps allow the light emitting device 110 to be manufactured.

The manufacturing method of the light emitting device 110 includes a step S102 of epitaxially growing AlGaN on the light emitting layer 34 to form a second semiconductor layer 36 having a first portion 36a and a second portion 36b that surrounds the first portion 36a in a plan view and has a higher Al composition ratio than the first portion 36a, and a step of etching the first portion 36a of the second semiconductor layer 36 to form a recess 40 in the second semiconductor layer 36. In addition, in the step S102 of forming the second semiconductor layer 36, the second semiconductor layer 36 is formed as a single layer spanning multiple columnar portions 30.

In this manufacturing method for the light emitting device 110, even if the second semiconductor layer 36 is a single layer spanning multiple columnar sections 30, a light emitting device in which the recesses 40 and the columnar sections 30 correspond one-to-one can be easily manufactured by utilizing the difference in etching rate due to the difference in the Al composition ratio in AlGaN.

2. Second embodiment 2.1. Light-emitting device Next, a light-emitting device according to a second embodiment will be described with reference to the drawings. Fig. 10 is a cross-sectional view showing a light-emitting device 200 according to the second embodiment. Hereinafter, in the light-emitting device 200 according to the second embodiment, components having the same functions as those of the light-emitting device 100 according to the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 10, in the light emitting device 200, like the light emitting device 100, the recesses 40 and the columnar portions 30 are provided in one-to-one correspondence, and the center of the recesses 40 and the columnar portions 30 overlap in a plan view.

In the light emitting device 200, the diameter of the second semiconductor layer 36 constituting the columnar section 30 is, for example, larger than the diameter of the first semiconductor layer 32 constituting the columnar section 30.

The light emitting device 200 can achieve the same effects as the light emitting device 100.

2.2. Manufacturing Method of the Light-Emitting Device Next, a manufacturing method of the light-emitting device 200 according to the second embodiment will be described with reference to the drawings. Fig. 11 is a flow chart showing an example of a manufacturing method of the light-emitting device 200 according to the second embodiment. Figs. 12 to 14 are cross-sectional views that typically show the manufacturing process of the light-emitting device 200 according to the second embodiment. Below, differences from the manufacturing method of the light-emitting device 100 described above will be described, and similarities will not be described.

2.2.1. Formation of columnar crystals (S200)
4, the first semiconductor layer 32 and the light emitting layer 34 are formed in a columnar shape on the substrate 10 to form a plurality of columnar crystals 3. Step S200 for forming the columnar crystals 3 is performed in the same manner as step S100 for forming the columnar crystals 3 described above.

2.2.2. Formation of GaN layer (S202)
12, a columnar GaN layer 4a is formed by epitaxially growing GaN on the light emitting layer 34. Examples of the method for epitaxial growth include MOCVD and MBE.

2.2.3. Formation of second semiconductor layer (S204)
13, AlGaN is epitaxially grown on the GaN layer 4a to form an AlGaN layer 4b covering the GaN layer 4a. This allows the second semiconductor layer 36 to be formed, which includes the GaN layer 4a and the AlGaN layer 4b. The epitaxial growth of AlGaN is performed under conditions that allow the AlGaN layer 4b to grow so as to cover the GaN layer 4a. For example, by controlling the amount of gas supplied, the growth temperature, and the like, the AlGaN layer 4b can be epitaxially grown so as to cover the GaN layer 4a.

This process forms a columnar section 30 consisting of a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36.

2.2.4. Formation of recesses (S206)
As shown in FIG. 14, the AlGaN layer 4b is etched to expose the GaN layer 4a, and the exposed GaN layer 4a is then etched to form a recess 40 in the second semiconductor layer .

Specifically, first, the AlGaN layer 4b is etched to expose the GaN layer 4a. The AlGaN layer 4b is etched by anisotropic etching from above using, for example, an ICP device. This allows the AlGaN layer 4b to be etched while preventing the first semiconductor layer 32 and the light emitting layer 34 from being etched. Here, the central portion of the AlGaN layer 4b has a lower Al composition ratio than the sidewall portion of the AlGaN layer 4b, so the etching rate of the central portion of the AlGaN layer 4b is higher than that of the sidewall portion of the AlGaN layer 4b. Therefore, when the AlGaN layer 4b is etched, the central portion of the AlGaN layer 4b is selectively etched.

When the etching of the AlGaN layer 4b progresses and the GaN layer 4a is exposed, the GaN layer 4a is selectively etched. This is because, as described above, the higher the Al composition ratio, the lower the etching rate. As a result, as shown in FIG. 14, a recess 40 is formed in the second semiconductor layer 36. The etching of the GaN layer 4a is performed by anisotropic etching from above using an ICP device or the like, similar to the etching of the AlGaN layer 4b described above.

The etching of the GaN layer 4a is stopped when part of the GaN layer 4a remains so as not to expose the light-emitting layer 34.

In this process, the GaN layer 4a is etched to form the recess 40, so that the recess 40 and the columnar section 30 can be placed in one-to-one correspondence. Furthermore, the center position of the recess 40 can be made to coincide with the center position of the columnar section 30 in a plan view.

2.2.5. Formation of electrodes (S208)
10 , a first electrode 50 is formed on the buffer layer 22, and a second electrode 52 is formed on the second semiconductor layer 36. Step S208 of forming the first electrode 50 and the second electrode 52 is performed in the same manner as step S106 of forming the first electrode 50 and the second electrode 52 described above.

The above steps allow the light emitting device 200 to be manufactured.

The manufacturing method for the light emitting device 200, like the manufacturing method for the light emitting device 100 described above, utilizes the difference in etching rate due to differences in the Al composition ratio in AlGaN, making it possible to easily manufacture a light emitting device in which the recesses 40 and the columnar sections 30 correspond one-to-one. In other words, it is possible to easily manufacture a light emitting device that can reduce the variation in the amount of current injected into each columnar section 30.

7 described above, the second semiconductor layer 36 may be a single layer provided across multiple columnar sections 30. In this case, in step S204 of forming the AlGaN layer 4b covering the GaN layer 4a, the AlGaN layer 4b may be formed thick. This allows adjacent AlGaN layers 4b to come into contact with each other and form a single layer across multiple columnar sections 30.

3. Third embodiment 3.1. Light-emitting device Next, a light-emitting device according to a third embodiment will be described with reference to the drawings. Fig. 15 is a cross-sectional view showing a light-emitting device 300 according to the third embodiment. Hereinafter, in the light-emitting device 300 according to the third embodiment, components having the same functions as those of the light-emitting device 100 according to the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 15, in the light emitting device 300, like the light emitting device 100, the recesses 40 and the columnar portions 30 are provided in one-to-one correspondence, and in a plan view, the center of the recesses 40 and the columnar portions 30 overlap.

In the light emitting device 300, the second semiconductor layer 36 is, for example, a p-type GaN layer.

The light emitting device 300 can achieve the same effects as the light emitting device 100.

3.2. Manufacturing Method of the Light-Emitting Device Next, a manufacturing method of the light-emitting device 300 according to the third embodiment will be described with reference to the drawings. Fig. 16 is a flow chart showing an example of a manufacturing method of the light-emitting device 300 according to the third embodiment. Figs. 17 to 18 are cross-sectional views that typically show the manufacturing process of the light-emitting device 300 according to the third embodiment. Below, differences from the manufacturing method of the light-emitting device 100 described above will be described, and similarities will not be described.

3.2.1. Formation of columnar crystals (S300)
4, a first semiconductor layer 32 and a light emitting layer 34 are formed in a columnar shape on the substrate 10 to form a plurality of columnar crystals 3. Step S300 for forming the columnar crystals 3 is performed in the same manner as step S100 for forming the columnar crystals 3 described above.

3.2.2. Formation of second semiconductor layer (S302)
17, GaN is epitaxially grown on the light emitting layer 34 to form a second semiconductor layer 36 having a first portion 6a and a second portion 6b. The first portion 6a is formed in the center of the columnar portion 30 in a plan view. The second portion 6b surrounds the first portion 6a in a plan view. The second portion 6b forms a sidewall portion of the columnar portion 30. The second portion 6b has better crystallinity than the first portion 6a.

In this process, GaN is epitaxially grown on the light-emitting layer 34. Examples of methods for epitaxial growth include MOCVD and MBE. When GaN is epitaxially grown, a portion with a high proportion of Ga is formed in the center of the columnar section 30. For example, when epitaxial growth is performed, Ga is aggregated in the center of the columnar section 30 by supplying an excess of Ga. As a result, the crystallinity of the center of the columnar section 30 deteriorates, and a first portion 6a with poor crystallinity and a second portion 6b with good crystallinity are formed.

This process forms a columnar section 30 consisting of a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36.

3.2.3. Formation of recesses (S304)
As shown in FIG. 18, the first portion 6 a of the second semiconductor layer 36 is etched to form a recess 40 in the second semiconductor layer 36 .

Generally, even for the same material, the worse the crystallinity, the higher the etching rate. Therefore, the etching rate of the first portion 6a is higher than the etching rate of the second portion 6b. Therefore, in this process, the recess 40 is formed by selectively etching the first portion 6a by utilizing the difference in etching rate between the first portion 6a and the second portion 6b.

The etching of the second semiconductor layer 36 is not particularly limited as long as it is a technique that can achieve a high selectivity between the first portion 6 a and the second portion 6 b, and may be anisotropic etching or isotropic etching. For example, the first portion 6 a can be selectively etched by etching using hydrogen fluoride.

In this process, the recess 40 is formed by etching the first portion 6a of the second semiconductor layer 36, so that the recess 40 and the columnar portion 30 can be placed in one-to-one correspondence. Furthermore, the center position of the recess 40 can be made to coincide with the center position of the columnar portion 30 in a plan view.

3.2.4. Formation of electrodes (S306)
15 , a first electrode 50 is formed on the buffer layer 22, and a second electrode 52 is formed on the second semiconductor layer 36. Step S306 of forming the first electrode 50 and the second electrode 52 is performed in the same manner as step S106 of forming the first electrode 50 and the second electrode 52 described above.

The above steps allow the light emitting device 300 to be manufactured.

As described above, the method for manufacturing the light-emitting device 300 makes it easy to manufacture a light-emitting device in which the recesses 40 and the columnar sections 30 correspond one-to-one by utilizing the difference in etching rate due to differences in crystallinity. In other words, it is easy to manufacture a light-emitting device that can reduce the variation in the amount of current injected into each columnar section 30.

7 described above, the second semiconductor layer 36 may be a single layer provided across multiple columnar sections 30. For example, in step S302 of forming the second semiconductor layer 36 described above, the second semiconductor layer 36 can be formed as a single layer provided across multiple columnar sections 30 by epitaxially growing GaN under conditions in which GaN grows not only in the stacking direction but also in the in-plane direction.

4. Fourth embodiment 4.1. Light-emitting device Next, a light-emitting device according to a fourth embodiment will be described with reference to the drawings. Fig. 19 is a cross-sectional view showing a light-emitting device 400 according to the fourth embodiment. Hereinafter, in the light-emitting device 400 according to the fourth embodiment, components having the same functions as those of the light-emitting device 100 according to the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 19, in the light emitting device 400, like the light emitting device 100, the recesses 40 and the columnar portions 30 are provided in one-to-one correspondence, and the center of the recesses 40 and the columnar portions 30 overlap in a plan view.

In the light-emitting device 400, the second semiconductor layer 36 is, for example, a p-type GaN layer. The recess 40 has a tapered shape in which the diameter of the opening of the recess 40 is larger than the diameter of the bottom of the recess 40. The shape of the recess 40 is, for example, a cone shape.

The light emitting device 400 can achieve the same effects as the light emitting device 100.

4.2. Manufacturing Method of the Light-Emitting Device Next, a manufacturing method of the light-emitting device 400 according to the fourth embodiment will be described with reference to the drawings. Fig. 20 is a flow chart showing an example of a manufacturing method of the light-emitting device 400 according to the fourth embodiment. Figs. 21 and 22 are cross-sectional views showing a schematic diagram of a manufacturing process of the light-emitting device 400 according to the fourth embodiment. Below, differences from the manufacturing method of the light-emitting device 100 described above will be described, and similarities will not be described.

4.2.1. Formation of columnar crystals (S400)
4, a first semiconductor layer 32 and a light emitting layer 34 are formed in a columnar shape on a substrate 10 to form a plurality of columnar crystals 3. Step S400 for forming the columnar crystals 3 is performed in the same manner as step S100 for forming the columnar crystals 3 described above.

4.2.2. Formation of second semiconductor layer (S402)
21, GaN is epitaxially grown on the light emitting layer 34 to form a second semiconductor layer 36 having a first portion 8a and a second portion 8b. The first portion 8a has a portion formed in the center of the columnar portion 30 in a plan view. In the example shown, the first portion 8a is formed in the upper portion of the columnar portion 30. The first portion 8a has a tapered portion 9 whose diameter decreases as it approaches the light emitting layer 34. The tapered portion 9 is formed in the center of the columnar portion 30 in a plan view. The first portion 8a is N-polar GaN.

The second portion 8b has a portion that surrounds the first portion 8a in a planar view. In the illustrated example, the second portion 8b surrounds the tapered portion 9 in a planar view. The second portion 8b is provided between the first portion 8a and the light-emitting layer 34 in the stacking direction. The second portion 8b is GaN with Ga polarity.

In this process, GaN is epitaxially grown on the light-emitting layer 34. Examples of methods for epitaxial growth include MOCVD and MBE. Here, for example, by supplying an excess of Mg during epitaxial growth, N-polarity GaN can be formed in the center of the columnar section 30. This allows the formation of a second semiconductor layer 36 having an N-polarity first portion 8a and a Ga-polarity second portion 8b.

This process forms a columnar section 30 consisting of a first semiconductor layer 32, a light emitting layer 34, and a second semiconductor layer 36.

4.2.3. Formation of recesses (S404)
As shown in FIG. 22, the first portion 8 a of the second semiconductor layer 36 is etched to form a recess 40 in the second semiconductor layer 36 .

The etching of the second semiconductor layer 36 is not particularly limited as long as it is a method that can achieve a high selectivity between the first portion 8a and the second portion 8b, and may be anisotropic etching or isotropic etching.

Here, the etching rate of N-polarity GaN with potassium hydroxide is higher than the etching rate of Ga-polarity GaN. Therefore, by etching the second semiconductor layer 36 with potassium hydroxide, the first portion 8a can be selectively etched.

In this manner, in this process, the recess 40 is formed by selectively etching the first portion 8a by utilizing the difference in etching rate between the first portion 8a and the second portion 8b.

In this process, the recess 40 is formed by etching the first portion 8a of the second semiconductor layer 36, so that the recess 40 and the columnar portion 30 can be in one-to-one correspondence. Furthermore, the position of the center of the recess 40 can be made to coincide with the position of the center of the columnar portion 30 in a plan view.

4.2.4. Formation of electrodes (S406)
19 , a first electrode 50 is formed on the buffer layer 22, and a second electrode 52 is formed on the second semiconductor layer 36. Step S306 of forming the first electrode 50 and the second electrode 52 is performed in the same manner as step S106 of forming the first electrode 50 and the second electrode 52 described above.

The above steps allow the light emitting device 400 to be manufactured.

As described above, the method for manufacturing the light-emitting device 400 makes it easy to manufacture a light-emitting device in which the recesses 40 and the columnar sections 30 correspond one-to-one by utilizing the difference in etching rate due to the difference in the polarity of the crystal. In other words, it is easy to manufacture a light-emitting device that can reduce the variation in the amount of current injected into each columnar section 30.

7 described above, the second semiconductor layer 36 may be a single layer provided across multiple columnar sections 30. For example, in step S402 of forming the second semiconductor layer 36 described above, the second semiconductor layer 36 can be a single layer provided across multiple columnar sections 30 by epitaxially growing GaN under conditions in which GaN grows not only in the stacking direction but also in the in-plane direction.

5. Fifth embodiment Next, a projector according to a fifth embodiment will be described with reference to the drawings. Fig. 23 is a diagram illustrating a projector 900 according to the fifth embodiment.

The projector 900 has, for example, a light-emitting device 100 as a light source.

Projector 900 has a housing (not shown) and red light source 100R, green light source 100G, and blue light source 100B that are provided in the housing and emit red light, green light, and blue light, respectively. For convenience, red light source 100R, green light source 100G, and blue light source 100B are simplified in FIG. 23.

The projector 900 further includes a first optical element 902R, a second optical element 902G, a third optical element 902B, a first light modulation device 904R, a second light modulation device 904G, a third light modulation device 904B, and a projection device 908, which are provided within the housing. The first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B are, for example, transmissive liquid crystal light valves. The projection device 908 is, for example, a projection lens.

Light emitted from red light source 100R is incident on first optical element 902R. The light emitted from red light source 100R is collected by first optical element 902R. Note that first optical element 902R may have a function other than collecting light. The same applies to second optical element 902G and third optical element 902B described below.

The light collected by the first optical element 902R is incident on the first light modulation device 904R. The first light modulation device 904R modulates the incident light according to image information. The projection device 908 then enlarges the image formed by the first light modulation device 904R and projects it onto the screen 910.

The light emitted from the green light source 100G is incident on the second optical element 902G.
The light emitted from the second optical element 900G is collected by the second optical element 902G.

The light collected by the second optical element 902G is incident on the second light modulation device 904G. The second light modulation device 904G modulates the incident light according to image information. The projection device 908 then enlarges the image formed by the second light modulation device 904G and projects it onto the screen 910.

The light emitted from the blue light source 100B is incident on the third optical element 902B. The light emitted from the blue light source 100B is collected by the third optical element 902B.

The light collected by the third optical element 902B is incident on the third light modulation device 904B. The third light modulation device 904B modulates the incident light according to image information. The projection device 908 then enlarges the image formed by the third light modulation device 904B and projects it onto the screen 910.

The projector 900 may also have a cross dichroic prism 906 that combines the light emitted from the first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B and directs the light to the projection device 908.

The three color lights modulated by the first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B are incident on the cross dichroic prism 906. The cross dichroic prism 906 is formed by bonding together four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged on its inner surface. The three color lights are combined by these dielectric multilayer films to form light that represents a color image. The combined light is then projected by the projection device 908 onto the screen 910, and an enlarged image is displayed.

The red light source 100R, the green light source 100G, and the blue light source 100B may directly form an image without using the first light modulation device 904R, the second light modulation device 904G, and the third light modulation device 904B, by controlling the light emitting device 100 as a pixel of the image according to image information. The projection device 908 may then enlarge and project the image formed by the red light source 100R, the green light source 100G, and the blue light source 100B onto the screen 910.

In the above example, a transmissive liquid crystal light valve is used as the light modulation device, but a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such light valves include a reflective liquid crystal light valve and a digital micro mirror device. The configuration of the projection device may be changed as appropriate depending on the type of light valve used.

The light source can also be applied to a light source device of a scanning type image display device having a scanning means, which is an image forming device that displays an image of a desired size on a display surface by scanning light from the light source on a screen.

The light-emitting device according to the above-described embodiment can be used for purposes other than projectors. Examples of uses other than projectors include light sources for indoor and outdoor lighting, display backlights, laser printers, scanners, car lights, sensing devices that use light, communication devices, etc.

In the present invention, some configurations may be omitted or each embodiment or modified example may be combined within the scope of the features and effects described in this application.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments. Substantially the same configurations are, for example, configurations that have the same functions, methods, and results, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that have the same effects as the configurations described in the embodiments, or that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

3...columnar crystal, 4a...GaN layer, 4b...AlGaN layer, 6a...first portion, 6b...second portion, 8a...first portion, 8b...second portion, 9...tapered portion, 10...substrate, 20...laminated body, 22...buffer layer, 30...columnar portion, 32...first semiconductor layer, 34...light-emitting layer, 36...second semiconductor layer, 36a...first portion, 36b...second portion, 40...recess, 42...low refractive index portion, 50...first electrode, 52...second electrode, 60...mask layer, 100...light-emitting device, 100R...red light source, 100G...green light source, 100B...blue light source, 110...light emitting device, 200...light emitting device, 300...light emitting device, 360...lower part, 362...upper part, 400...light emitting device, 900...projector, 902R...first optical element, 902G...second optical element, 902B...third optical element, 904R...first light modulation device, 904G...second light modulation device, 904B...third light modulation device, 906...cross dichroic prism, 908...projection device, 910...screen

Claims (10)

A substrate;
a laminate provided on the substrate and having a plurality of columnar portions;
having
The laminate comprises:
A first semiconductor layer;
A second semiconductor layer having a conductivity type different from that of the first semiconductor layer;
a light emitting layer provided between the first semiconductor layer and the second semiconductor layer;
having
the first semiconductor layer and the light emitting layer constitute the columnar portion,
the first semiconductor layer is provided between the substrate and the light emitting layer,
The second semiconductor layer is provided with a recess.
a low refractive index portion having a refractive index lower than that of the second semiconductor layer is provided in the recess;
The light emitting device, wherein the recesses and the columnar portions are provided in one-to-one correspondence. In claim 1,
The light emitting device, wherein a center of the recess and a center of the columnar portion overlap in a plan view. In claim 1 or 2,
the second semiconductor layer is a single layer provided across a plurality of the columnar portions. In claim 1 or 2,
The second semiconductor layer constitutes the columnar portion. In any one of claims 1 to 4,
The light emitting device, wherein the low refractive index portion is a gap. A projector having a light-emitting device according to any one of claims 1 to 5. forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing AlGaN on the light emitting layer to form a second semiconductor layer having a first portion and a second portion surrounding the first portion in a plan view and having a higher Al composition ratio than the first portion, the second semiconductor layer having a different conductivity type from the first semiconductor layer;
etching the first portion of the second semiconductor layer to form a recess in the second semiconductor layer;
The method for manufacturing a light emitting device comprising the steps of: forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing GaN on the light emitting layer to form a columnar GaN layer;
epitaxially growing AlGaN on the GaN layer to form a second semiconductor layer having an AlGaN layer covering the GaN layer and a conductivity type different from that of the first semiconductor layer;
etching the AlGaN layer to expose the GaN layer, and etching the exposed GaN layer to form a recess in the second semiconductor layer;
The method for manufacturing a light emitting device comprising the steps of: forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing GaN on the light emitting layer to form a second semiconductor layer having a first portion and a second portion surrounding the first portion in a plan view and having better crystallinity than the first portion, the second semiconductor layer having a different conductivity type from the first semiconductor layer;
etching the first portion of the second semiconductor layer to form a recess in the second semiconductor layer;
The method for manufacturing a light emitting device comprising the steps of: forming a first semiconductor layer and a light emitting layer in a columnar shape on a substrate to form a plurality of columnar crystals;
epitaxially growing GaN on the light emitting layer to form a second semiconductor layer having a first portion with N polarity and a second portion with Ga polarity surrounding the first portion in a plan view, the second semiconductor layer having a different conductivity type from the first semiconductor layer;
etching the first portion of the second semiconductor layer to form a recess in the second semiconductor layer;
The method for manufacturing a light emitting device comprising the steps of:

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