JP7634836B2 - Light emitting device and projector - Google Patents

Description

The present invention relates to a light-emitting device and a projector.

Semiconductor lasers are expected to be the next generation of high-brightness light sources. In particular, semiconductor lasers that incorporate nanocolumns are expected to be able to achieve high-output light emission with a narrow radiation angle due to the photonic crystal effect of the nanocolumns.

For example, Patent Document 1 describes a semiconductor light-emitting device in which an n-type GaN nanocolumn layer and a light-emitting layer are formed on a silicon substrate, a p-type GaN contact layer is epitaxially grown while expanding the nanocolumn diameter, and a semi-transparent p-type electrode is formed on top of the layer.

JP 2007-49062 A

However, in Patent Document 1, the p-type GaN layer is one continuous layer spanning multiple nanocolumns, which increases the average refractive index in the in-plane direction of the layer. This makes it difficult to confine light in the light-emitting layer, and light generated in the light-emitting layer leaks to the electrode side. When light leaks to the electrode side, it is absorbed by the electrode, resulting in loss.

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;
an electrode provided on the opposite side of the stack to the substrate, the electrode injecting a current into the stack;
having
The columnar portion is
A first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type different from the first conductivity type;
a light emitting layer provided between the first semiconductor layer and the second semiconductor layer;
having
the first semiconductor layer is provided between the substrate and the light emitting layer,
the stacked body includes an AlN layer provided between the second semiconductor layers of the adjacent columnar portions,
The refractive index of the AlN layer is lower than the refractive index of the second semiconductor layer.

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

FIG. 1 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a light emitting device according to a reference example. 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. FIG. 1 is a diagram illustrating a projector according to an embodiment of the present invention.

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. Light-emitting device First, the light-emitting device according to the present embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view that shows a schematic diagram of a light-emitting device 100 according to the present embodiment.

As shown in FIG. 1, the light-emitting device 100 has, for example, a substrate 10, a laminate 20, a first electrode 70, and a second electrode 72. The light-emitting device 100 is a semiconductor laser.

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

The laminate 20 is provided on the substrate 10. In the illustrated example, the laminate 20 is provided on the substrate 10. The laminate 20 has, for example, a buffer layer 22, a columnar section 30, an insulating layer 40, an AlN layer 50, and a third semiconductor layer 60.

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." The direction perpendicular to the stacking direction is also referred to as the "in-plane direction." The "stacking direction of the laminate 20" refers to the stacking direction of the first semiconductor layer 32 and the light emitting layer 34 of the columnar section 30.

The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is, for example, an n-type GaN layer doped with Si.

The columnar section 30 is provided on the buffer layer 22. The columnar section 30 has a columnar shape that protrudes upward from the buffer layer 22. In other words, the columnar section 30 protrudes upward from the substrate 10 via the buffer layer 22. The columnar section 30 is also called, for example, a nanocolumn, a nanowire, a nanorod, or a nanopillar. The planar shape of the columnar section 30 is, for example, a polygon such as a hexagon, or a circle.

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 high-quality crystalline light-emitting layer 34 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 "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 smallest circle that contains the polygon inside, and when the planar shape of the columnar portion 30 is an ellipse, the diameter of the smallest circle that contains the ellipse inside.

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 as viewed from the stacking direction. The plurality of columnar sections 30 are arranged, for example, in a triangular lattice or square lattice pattern. The plurality of columnar sections 30 can exhibit the effect of a photonic crystal.

The "pitch of the columnar portions" refers to 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 a semiconductor layer of a first conductivity type. The first semiconductor layer 32 is, for example, an n-type GaN layer doped with Si.

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, for example, a well layer and a barrier layer. The well layer and the barrier layer are i-type semiconductor layers that are not intentionally doped with impurities. The well layer is, for example, an InGaN layer. The barrier layer is, for example, a GaN layer. The light-emitting layer 34 has an MQW (Multiple Quantum Well) structure composed of the well layer and the barrier layer.

The number of well layers and barrier layers constituting the light-emitting layer 34 is not particularly limited. For example, only one well layer may be provided, in which case the light-emitting layer 34 has a SQW (single quantum well) structure.

The second semiconductor layer 36 is provided on the light emitting layer 34. The second semiconductor layer 36 is a semiconductor layer of a second conductivity type different from the first conductivity type. The second semiconductor layer 36 is, for example, a p-type GaN 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.

Although not shown, an OCL (Optical Confinement Layer) made of an i-type InGaN layer and a GaN layer may be provided at least one between the first semiconductor layer 32 and the light emitting layer 34 and between the light emitting layer 34 and the second semiconductor layer 36. The second semiconductor layer 36 may also have an EBL (Electron Blocking Layer) made of a p-type AlGaN layer.

In the light-emitting device 100, a pin diode is formed by a p-type second semiconductor layer 36, an i-type light-emitting layer 34 that is not intentionally doped with impurities, and an 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 70 and the second electrode 72, 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 the in-plane direction, 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. The light-emitting device 100 then emits the +1st order diffracted light and the -1st order diffracted light as laser light in the stacking direction.

Although not shown, a reflective layer may be provided between the substrate 10 and the buffer layer 22 or under the substrate 10. The reflective layer is, for example, a DBR (Distributed Bragg Reflector) layer. The reflective layer can reflect light generated in the light-emitting layer 34, and the light-emitting device 100 can emit light only from the second electrode 72 side.

The insulating layer 40 is provided between the light emitting layers 34 of the adjacent columnar sections 30. In the illustrated example, the insulating layer 40 covers the side surfaces of the light emitting layers 34. When viewed from the stacking direction, the insulating layer 40 surrounds the light emitting layers 34. In the illustrated example, the insulating layer 40 has a shape in which a recess 42 is provided on the lower surface. A part of the insulating layer 40 is provided, for example, between the first semiconductor layers 32 of the adjacent columnar sections 30. The refractive index of the insulating layer 40 is lower than the refractive index of the light emitting layers 34. The refractive index of the insulating layer 40 is lower than the refractive index of the AlN layer 50, for example. The insulating layer 40 is, for example, an Al ₂ O ₃ layer.

The AlN layer 50 is provided on the insulating layer 40. The AlN layer 50 is provided between the second semiconductor layers 36 of adjacent columnar sections 30. The insulating layer 40 surrounds the second semiconductor layer 36 when viewed from the stacking direction. The refractive index of the AlN layer 50 is lower than the refractive index of the second semiconductor layer 36. The AlN layer 50 is insulating. The AlN layer 50 is a layer made of aluminum nitride.

The AlN layer 50 has a first end 52 on the substrate 10 side. In the illustrated example, the first end 52 is formed on the lower surface of the AlN layer 50. The light-emitting layer 34 has a second end 35 on the opposite side to the substrate 10. The second end 35 is the end on the second electrode 72 side. In the illustrated example, the second end 35 is formed on the upper surface of the light-emitting layer 34. The distance D1 between the first end 52 and the substrate 10 is equal to or greater than the distance D2 between the second end 35 and the substrate 10. In the illustrated example, the distance D1 is equal to the distance D2. Although not illustrated, the distance D1 may be greater than the distance D2. The position of the first end 52 can be adjusted by the position of the insulating layer 40 in the stacking direction. The AlN layer 50 is spaced apart from the light-emitting layer 34. The AlN layer 50 is not provided between the light-emitting layers 34 of adjacent columnar sections 30.

The top surface of the AlN layer 50 and the top surface of the second semiconductor layer 36 are, for example, flush with each other. This allows the flatness of the third semiconductor layer 60 to be increased, and the flatness of the second electrode 72 to be increased. This allows current to be injected uniformly into the multiple columnar sections 30.

The third semiconductor layer 60 is provided between the second semiconductor layer 36 and the second electrode 72. The third semiconductor layer 60 is further provided between the AlN layer 50 and the second electrode 72. The third semiconductor layer 60 is provided across the AlN layer 50 and the multiple columnar sections 30. The third semiconductor layer 60 is a semiconductor layer of the second conductivity type. The second semiconductor layer 36 is, for example, a p-type GaN layer doped with Mg. The impurity concentration of the third semiconductor layer 60 is higher than the impurity concentration of the second semiconductor layer 36. It can be confirmed, for example, by atom probe analysis that the impurity concentration of the third semiconductor layer 60 is higher than the impurity concentration of the second semiconductor layer 36.

The first electrode 70 is provided on the buffer layer 22. The buffer layer 22 may be in ohmic contact with the first electrode 70. The first electrode 70 is electrically connected to the first semiconductor layer 32. In the illustrated example, the first electrode 70 is electrically connected to the first semiconductor layer 32 via the buffer layer 22. The first electrode 70 is one of the electrodes for injecting a current into the light-emitting layer 34. As the first electrode 70, 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 72 is provided on the third semiconductor layer 60. The second electrode 72 is provided on the side of the stacked body 20 opposite to the substrate 10. The third semiconductor layer 60 may be in ohmic contact with the second electrode 72. The second electrode 72 is electrically connected to the second semiconductor layer 36. In the illustrated example, the second electrode 72 is electrically connected to the second semiconductor layer 36 via the third semiconductor layer 60. The second electrode 72 is the other electrode for injecting a current into the light-emitting layer 34. For example, ITO (indium tin oxide) or the like is used as the second electrode 72.

In the above, an example in which a gap is provided between the first semiconductor layers 32 of adjacent columnar sections 30 has been described, but an AlN layer may be provided between the first semiconductor layers 32 of adjacent columnar sections 30.

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

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

In the light emitting device 100, the stack 20 has an AlN layer 50 provided between the second semiconductor layers 36 of adjacent columnar sections 30, and the refractive index of the AlN layer 50 is lower than the refractive index of the second semiconductor layer 36. Therefore, in the light emitting device 100, the average refractive index in the in-plane direction of the AlN layer 50 (the average refractive index in the in-plane direction of the portion of the stack 20 where the AlN layer 50 is provided) can be lowered compared to when the second semiconductor layer is a single continuous layer across multiple columnar sections. This allows the peak of the light intensity in the stacking direction to be aligned with the position of the light emitting layer 34, as shown in FIG. 1.

For example, as shown in FIG. 2, when the second semiconductor layer 1036 grows while expanding in diameter, and the second semiconductor layer 1036 has a continuous portion 1038 that is a single layer that is continuous across multiple columnar portions 1030, the average refractive index in the in-plane direction in the continuous portion 1038 becomes high. Therefore, as shown in FIG. 2, the peak of the light intensity in the stacking direction shifts toward the second electrode 1072. FIG. 2 is a cross-sectional view that shows a schematic diagram of a light emitting device 1000 according to a reference example. The light emitting device 1000 has a substrate 1010, a buffer layer 1022, a columnar portion 1030, a first electrode 1070, and a second electrode 1072. The columnar portion 1030 has a first semiconductor layer 1032, a light emitting layer 1034, and a second semiconductor layer 1036.

As described above, in the light-emitting device 100, light can be confined in the light-emitting layer 34, compared to the light-emitting device 1000. As a result, in the light-emitting device 100, the amount of light leaking to the second electrode 72 side can be reduced, and the amount of light absorbed by the second electrode 72 can be reduced.

In the light emitting device 100, the AlN layer 50 has a first end 52 on the substrate 10 side, the light emitting layer 34 has a second end 35 on the opposite side to the substrate 10, and the distance D1 between the first end 52 and the substrate 10 is equal to or greater than the distance D2 between the second end 35 and the substrate 10. Therefore, in the light emitting device 100, the refractive index difference between the light emitting layer 34 and the portion between the light emitting layers 34 of the adjacent columnar sections 30 can be made larger than when the distance D1 is smaller than the distance D2. This makes it possible to more reliably realize the effect of the photonic crystal. For example, if the distance D1 is smaller than the distance D2 and an AlN layer is present between the light emitting layers of the adjacent columnar sections, the refractive index difference between the light emitting layer and the portion between the light emitting layers of the adjacent columnar sections becomes smaller.

In the light emitting device 100, the stacked body 20 has a third semiconductor layer 60 of the second conductivity type provided between the second semiconductor layer 36 and the second electrode 72, and the impurity concentration of the third semiconductor layer 60 is higher than the impurity concentration of the second semiconductor layer 36. Therefore, in the light emitting device 100, the contact resistance between the stacked body 20 and the second electrode 72 can be reduced compared to a case in which the third semiconductor layer is not provided. This can increase the current injection efficiency.

In the light emitting device 100, the third semiconductor layer 60 is provided between the AlN layer 50 and the second electrode 72. Therefore, in the light emitting device 100, the flatness of the second electrode 72 can be improved compared to a case where the third semiconductor layer is not provided between the AlN layer and the second electrode. This allows current to be injected uniformly into the multiple columnar sections 30.

2. Method for Manufacturing the Light-Emitting Device Next, a method for manufacturing the light-emitting device 100 according to this embodiment will be described with reference to the drawings. Figures 3 to 5 are cross-sectional views that typically show the manufacturing process of the light-emitting device 100 according to this embodiment.

As shown in FIG. 3, the buffer layer 22 is epitaxially grown on the substrate 10. Examples of the epitaxial growth method include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

Next, a mask layer (not shown) is formed on the buffer layer 22. The mask layer is formed, for example, by deposition using an electron beam deposition method or a sputtering method, and patterning. The patterning is performed, for example, by photolithography and etching. The mask layer is, for example, a silicon oxide layer, a titanium layer, a titanium oxide layer, an aluminum oxide layer, etc.

Next, the first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 are epitaxially grown in this order on the buffer layer 22 using the mask layer as a mask. An example of a method for epitaxial growth is the MBE method. The MBE method is easier to form a columnar shape than the MOCVD method. This process makes it possible to form multiple columnar sections 30.

As shown in FIG. 4, an insulating layer 40 is formed between the light-emitting layers 34 of adjacent columnar sections 30. The insulating layer 40 is formed, for example, by an ALD (Atomic Layer Deposition) method. For example, the insulating layer 40 does not reach the buffer layer 22, and has a recess 42 on the lower surface. A gap is formed between the insulating layer 40 and the buffer layer 22.

Next, the AlN layer 50 is epitaxially grown on the second semiconductor layer 36 and on the sides of the second semiconductor layer 36. For example, the MOCVD method can be used as a method for epitaxial growth. The MOCVD method is easier to grow laterally than the MBE method, and the space surrounded by the adjacent columnar sections 30 and insulating layers 40 can be filled with the AlN layer 50. Furthermore, since the AlN layer 50 is epitaxially grown, a highly uniform layer can be formed.

As shown in FIG. 5, the AlN layer 50 and the second semiconductor layer 36 are etched back. The etch back is performed, for example, using an ICP (Inductively Coupled Plasma) type etching device. Since the second semiconductor layer 36 and the AlN layer 50 are both III-IV compound semiconductors, the difference in etching rate is small. Therefore, for example, the top surface of the second semiconductor layer 36 and the top surface of the AlN layer 50 can be made flush with each other.

As shown in FIG. 1, the third semiconductor layer 60 is epitaxially grown on the second semiconductor layer 36 and the AlN layer 50. The epitaxial growth method may be, for example, the MOCVD method.

Next, a first electrode 70 is formed on the buffer layer 22, and a second electrode 7 is formed on the third semiconductor layer 60.
The first electrode 70 and the second electrode 72 are formed by, for example, a vacuum deposition method. The order in which the first electrode 70 and the second electrode 72 are formed is not particularly limited.

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

The second electrode 72 may be, for example, a high-concentration n-type GaN layer doped with Si. The impurity concentration of the high-concentration GaN layer is higher than the impurity concentration of the first semiconductor layer 32. The high-concentration GaN layer is tunnel-junctioned with the third semiconductor layer 60. The high-concentration GaN layer is epitaxially grown by, for example, the MBE method.

3. Projector Next, a projector according to this embodiment will be described with reference to the drawings. Fig. 6 is a diagram illustrating a schematic diagram of a projector 900 according to this 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. 6.

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. 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 green light source 100G 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 a third optical modulation device 904B.
The third light modulation device 904B modulates the incident light in accordance with image information, and the projection device 908 enlarges the image formed by the third light modulation device 904B and projects it onto a 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 was 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, displays, laser printers, scanners, car lights, sensing devices that use light, and communication devices.

The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example configurations with the same functions, methods and results, or configurations with 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 achieve the same effects as the configurations described in the embodiments, or configurations 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.

The following can be derived from the above-described embodiment and variant examples:

One aspect of the light emitting device is
A substrate;
a laminate provided on the substrate and having a plurality of columnar portions;
an electrode provided on the opposite side of the stack to the substrate, the electrode injecting a current into the stack;
having
The columnar portion is
A first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type different from the first conductivity type;
a light emitting layer provided between the first semiconductor layer and the second semiconductor layer;
having
the first semiconductor layer is provided between the substrate and the light emitting layer,
the stacked body includes an AlN layer provided between the second semiconductor layers of the adjacent columnar portions,
The refractive index of the AlN layer is lower than the refractive index of the second semiconductor layer.

This light-emitting device can reduce light leaking to the electrode side and light absorbed by the electrode.

In one embodiment of the light emitting device,
the AlN layer has a first end facing the substrate;
the light emitting layer has a second end opposite the substrate;
The distance between the first end and the substrate may be greater than or equal to the distance between the second end and the substrate.

This light-emitting device can increase the refractive index difference between the light-emitting layer and the area between the light-emitting layers of adjacent columnar sections.

In one embodiment of the light emitting device,
the stacked body includes a third semiconductor layer of the second conductivity type provided between the second semiconductor layer and the electrode,
The third semiconductor layer may have an impurity concentration higher than an impurity concentration of the second semiconductor layer.

This light-emitting device can reduce the contact resistance between the laminate and the electrodes.

In one embodiment of the light emitting device,
The third semiconductor layer may be provided between the AlN layer and the electrode.

This light-emitting device allows the electrodes to be highly flat.

One aspect of the projector is
The present invention has one aspect of the light emitting device.

10...substrate, 20...laminated body, 22...buffer layer, 30...columnar portion, 32...first semiconductor layer, 34...light-emitting layer, 35...second end, 36...second semiconductor layer, 40...insulating layer, 42...recess, 50...AlN layer, 52...first end, 60...third semiconductor layer, 70...first electrode, 72...second electrode, 100...light-emitting device, 100R...red light source, 100G...green light source, 100B...blue light source, 900...projector, 902R...first optical element, 902G...second optical element child, 902B...third optical element, 904R...first optical modulation device, 904G...second optical modulation device, 904B...third optical modulation device, 906...cross dichroic prism, 908...projection device, 910...screen, 1000...light emitting device, 1010...substrate, 1022...buffer layer, 1030...columnar portion, 1032...first semiconductor layer, 1034...light emitting layer, 1036...second semiconductor layer, 1038...continuous portion, 1070...first electrode, 1072...second electrode

Claims (4)

A substrate;
a laminate provided on the substrate and having a plurality of columnar portions;
an electrode provided on the opposite side of the stack to the substrate, the electrode injecting a current into the stack;
having
The columnar portion is
A first semiconductor layer of a first conductivity type;
a second semiconductor layer of a second conductivity type different from the first conductivity type;
a light emitting layer provided between the first semiconductor layer and the second semiconductor layer;
having
the first semiconductor layer is provided between the substrate and the light emitting layer,
the stacked body includes an AlN layer provided between the second semiconductor layers of the adjacent columnar portions,
The refractive index of the AlN layer is lower than the refractive index of the second semiconductor layer,
the AlN layer has a first end facing the substrate;
the light emitting layer has a second end opposite the substrate;
A light emitting device , wherein a distance between the first end and the substrate is greater than or equal to a distance between the second end and the substrate . In claim 1 ,
the stacked body includes a third semiconductor layer of the second conductivity type provided between the second semiconductor layer and the electrode,
A light emitting device, wherein the third semiconductor layer has an impurity concentration higher than an impurity concentration of the second semiconductor layer. In claim 2 ,
The third semiconductor layer is provided between the AlN layer and the electrode. A projector comprising the light emitting device according to claim 1 .

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