Light emitting device and projector

Abstract

To provide a light emitting device that can reduce light absorbed by an electrode.SOLUTION: A light emitting device has: a substrate; a laminate that is provided on the substrate and has a plurality of columnar parts; and an electrode that is provided on a side of the laminate opposite to the substrate and injects current to the laminate. The columnar parts each have a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type different from the first conductivity type, and a luminous layer provided between the first semiconductor layer and the second semiconductor layer. The first semiconductor layer is provided between the substrate and the luminous layer. The laminate has an AlN layer provided between the second semiconductor layers of the adjacent columnar parts. The refractive index of the AlN layer is lower than the refractive index of the second semiconductor layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light emitting device and a projector. [Background technology]

[0002] Semiconductor lasers are expected to become 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.

[0003] For example, Patent Document 1 describes a semiconductor light-emitting element 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 semitransparent p-type electrode is formed on top of the n-type GaN nanocolumn layer and light-emitting layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-49062 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, the p-type GaN layer is one continuous layer spanning multiple nanocolumns, so the average refractive index in the in-plane direction in the layer is high. This makes it difficult to confine light in the light-emitting layer, and the 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. [Means for solving the problem]

[0006] 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.

[0007] One aspect of the projector according to the present invention is The present invention has one aspect of the light emitting device. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a cross-sectional view illustrating a light emitting device according to a reference example. [Diagram 3] 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. [Figure 4] 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. [Diagram 5] 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. [Figure 6] FIG. 1 is a diagram illustrating a projector according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are necessarily essential components of the present invention.

[0010] 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.

[0011] 1, the light emitting device 100 includes, 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.

[0012] The substrate 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, a SiC substrate, or the like.

[0013] The laminate 20 is provided on a substrate 10. In the illustrated example, the laminate 20 is provided on the substrate 10. The laminate 20 includes, for example, a buffer layer 22, a columnar section 30, an insulating layer 40, an AlN layer 50, and a third semiconductor layer 60.

[0014] 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 "upper", and the direction from the light emitting layer 34 toward the first semiconductor layer 32 is described as "lower". A direction perpendicular to the stacking direction is also referred to as an "in-plane direction". Moreover, 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.

[0015] 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.

[0016] The columnar section 30 is provided on the buffer layer 22. The columnar section 30 has a columnar shape protruding 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.

[0017] 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, it is possible to obtain a light-emitting layer 34 of high quality crystals and reduce distortion inherent in the light-emitting layer 34. This allows the light generated in the light-emitting layer 34 to be amplified with high efficiency.

[0018] 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 includes the polygon, and when the planar shape of the columnar portion 30 is an ellipse, the diameter of the smallest circle that includes the ellipse.

[0019] A plurality of columnar sections 30 are provided. The interval between adjacent columnar sections 30 is, for example, 1 nm or less. The thickness is 500 nm or less. The multiple columnar sections 30 are arranged in a predetermined direction at a predetermined pitch when viewed from the stacking direction. The multiple columnar sections 30 are arranged in, for example, a triangular lattice or square lattice pattern. The multiple columnar sections 30 can exhibit the effect of a photonic crystal.

[0020] The "pitch of the columnar portion" is the distance between the centers of adjacent columnar portions 30 along a predetermined direction. When the planar shape of the columnar portion 30 is a circle, the "center of the columnar portion" is the center of the circle, and when the planar shape of the columnar portion 30 is a shape other than a circle, the center of the smallest inclusive circle. For example, when the planar shape of the columnar portion 30 is a polygon, the center of the columnar portion 30 is the center of the smallest circle that includes the polygon inside, and when the planar shape of the columnar portion 30 is an ellipse, the center of the smallest circle that includes the ellipse inside.

[0021] The columnar section 30 has a first semiconductor layer 32, a light emitting layer , and a second semiconductor layer .

[0022] 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.

[0023] 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.

[0024] There is no particular limitation on the number of well layers and barrier layers constituting the light-emitting layer 34. For example, only one well layer may be provided, in which case the light-emitting layer 34 has a SQW (Single Quantum Well) structure.

[0025] 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 having the function of confining light in the light emitting layer 34.

[0026] 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 have an EBL (Electron Blocking Layer) made of a p-type AlGaN layer.

[0027] In the light emitting device 100, a pin diode is formed by the p-type second semiconductor layer 36, the i-type light emitting layer 34 that is not intentionally doped with impurities, 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 70 and the second electrode 72, a current is injected into the light emitting layer 34, and recombination of electrons and holes occurs 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, receives gain in the light emitting layer 34, and oscillates 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.

[0028] Although not shown in the figure, a thin film is formed between the substrate 10 and the buffer layer 22 or below the substrate 10. A reflective layer may be provided on the light-emitting layer 34. The reflective layer may be, for example, a DBR (Distributed Bragg Reflector) layer. The reflective layer can reflect the light generated in the light-emitting layer 34, and the light-emitting device 100 can emit light only from the second electrode 72 side.

[0029] 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 layer 34. The insulating layer 40 surrounds the light emitting layer 34 when viewed from the stacking direction. 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 layer 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 Al2O3 layer.

[0030] The AlN layer 50 is provided on the insulating layer 40. The AlN layer 50 is provided between the second semiconductor layers 36 of the 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.

[0031] The AlN layer 50 has a first end 52 on the substrate 10 side. In the illustrated example, the first end 52 is formed by 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 by 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 separated from the light emitting layer 34. The AlN layer 50 is not provided between the light emitting layers 34 of the adjacent columnar sections 30.

[0032] The upper surface of the AlN layer 50 and the upper surface of the second semiconductor layer 36 are, for example, flush with each other. This makes it possible to increase the flatness of the third semiconductor layer 60, and therefore the flatness of the second electrode 72. This makes it possible to inject current into the multiple columnar sections 30 with good uniformity.

[0033] 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 a 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 that the impurity concentration of the third semiconductor layer 60 is higher than the impurity concentration of the second semiconductor layer 36 by, for example, atom probe analysis.

[0034] 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.

[0035] The second electrode 72 is provided on the third semiconductor layer 60. The second electrode 72 is provided on the side of the laminate 20 opposite to the substrate 10. The third semiconductor layer 60 is in ohmic contact with the second electrode 72. The second electrode 72 may be in contact with 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. The second electrode 72 is made of, for example, ITO (indium tin oxide).

[0036] In the above, an example has been described in which a gap is provided between the first semiconductor layers 32 of adjacent columnar sections 30, but an AlN layer may also be provided between the first semiconductor layers 32 of adjacent columnar sections 30.

[0037] Although the above describes the InGaN-based light emitting layer 34, various material systems capable of emitting light when a current is injected depending on the wavelength of the emitted light can be used for 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.

[0038] The light emitting device 100 has, for example, the following advantages.

[0039] In the light emitting device 100, the stacked body 20 has an AlN layer 50 provided between the second semiconductor layers 36 of the 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 stacked body 20 where the AlN layer 50 is provided) can be made lower than when the second semiconductor layer is one 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.

[0040] For example, as shown in FIG. 2, when the second semiconductor layer 1036 grows while expanding its 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 typically shows 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.

[0041] As described above, in the light emitting device 100, light can be confined in the light emitting layer 34 more effectively than in the light emitting device 1000. As a result, in the light emitting device 100, the amount of light leaking toward the second electrode 72 can be reduced, and the amount of light absorbed by the second electrode 72 can be reduced.

[0042] 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, when 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 is reduced.

[0043] In the light emitting device 100, the laminate 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 laminate 20 and the second electrode 72 can be reduced compared to a case where the third semiconductor layer is not provided. This makes it possible to increase the efficiency of current injection.

[0044] 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 into the multiple columnar sections 30 with good uniformity.

[0045] 2. Manufacturing method of 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 for the light emitting device 100 according to this embodiment.

[0046] 3, the buffer layer 22 is epitaxially grown on the substrate 10. Examples of the epitaxial growth method include a metal organic chemical vapor deposition (MOCVD) method and a molecular beam epitaxy (MBE) method.

[0047] Next, a mask layer (not shown) is formed on the buffer layer 22. The mask layer is formed by, for example, deposition using an electron beam deposition method or a sputtering method, and patterning. The patterning is performed by, for example, photolithography and etching. The mask layer is, for example, a silicon oxide layer, a titanium layer, a titanium oxide layer, an aluminum oxide layer, or the like.

[0048] 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. As a method for epitaxial growth, for example, the MBE method can be mentioned. The MBE method is easier to form a columnar shape than the MOCVD method. By this process, a plurality of columnar portions 30 can be formed.

[0049] 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.

[0050] Next, the AlN layer 50 is epitaxially grown on the second semiconductor layer 36 and on the sides of the second semiconductor layer 36. An example of a method for epitaxial growth is the MOCVD method. The MOCVD method is easier to grow in the lateral direction than the MBE method, and the AlN layer 50 can fill the space surrounded by the adjacent columnar sections 30 and insulating layer 40. Furthermore, since the AlN layer 50 is epitaxially grown, a highly uniform layer can be formed.

[0051] 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 etching device of the ICP (Inductively Coupled Plasma) type. Since the second semiconductor layer 36 and the AlN layer 50 are both III-IV group compound semiconductors, the difference in etching rate is small. Therefore, for example, the upper surface of the second semiconductor layer 36 and the upper surface of the AlN layer 50 can be made flush with each other.

[0052] 1, the third semiconductor layer 60 is epitaxially grown on the second semiconductor layer 36 and the AlN layer 50. As a method for epitaxial growth, for example, the MOCVD method can be mentioned.

[0053] 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.

[0054] Through the above steps, the light emitting device 100 can be manufactured.

[0055] Alternatively, for example, a high-concentration n-type GaN layer doped with Si may be used as the second electrode 72. 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.

[0056] 3. Projector Next, a projector according to this embodiment will be described with reference to the drawings. Fig. 6 is a diagram illustrating a projector 900 according to this embodiment.

[0057] The projector 900 includes, for example, a light emitting device 100 as a light source.

[0058] 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.

[0059] 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 in 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.

[0060] The 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 later.

[0061] 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 in accordance with 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.

[0062] The light emitted from green light source 100G is incident on second optical element 902G. The light emitted from green light source 100G is collected by second optical element 902G.

[0063] 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 in accordance with 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.

[0064] The light emitted from blue light source 100B is incident on third optical element 902B. The light emitted from blue light source 100B is collected by third optical element 902B.

[0065] The light collected by the third optical element 902B is incident on the third optical modulation device 904B. The third light modulation device 904B modulates the incident light in accordance with image information. The projection device 908 then projects the image formed by the third light modulation device 904B onto a screen 910 in an enlarged scale.

[0066] 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 guides the combined light to the projection device 908.

[0067] 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 enter a cross dichroic prism 906. The cross dichroic prism 906 is formed by bonding four right-angle prisms together, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are disposed on its inner surface. The three color lights are synthesized by these dielectric multilayer films to form light that represents a color image. The synthesized light is then projected by a projection device 908 onto a screen 910, and an enlarged image is displayed.

[0068] Note that red light source 100R, green light source 100G, and blue light source 100B may directly form an image without using first light modulation device 904R, second light modulation device 904G, and third light modulation device 904B, by controlling light emitting device 100 as pixels of an image according to image information. Then, projection device 908 may enlarge and project the image formed by red light source 100R, green light source 100G, and blue light source 100B onto screen 910.

[0069] 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 is changed as appropriate depending on the type of light valve used.

[0070] 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.

[0071] The light emitting devices according to the above-described embodiments can be used in applications other than projectors, such as indoor and outdoor lighting, displays, laser printers, scanners, car lights, sensing devices that use light, and light sources for communication devices.

[0072] 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 effects. 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.

[0073] The following can be derived from the above-described embodiment and modifications.

[0074] 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.

[0075] According to this light emitting device, it is possible to reduce light leaking to the electrode side, and to reduce light absorbed by the electrode.

[0076] 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.

[0077] According to this light emitting device, it is possible to increase the difference in refractive index between the light emitting layer and the portion between the light emitting layers of the adjacent columnar portions.

[0078] 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 a higher impurity concentration than the second semiconductor layer.

[0079] According to this light emitting device, the contact resistance between the laminate and the electrodes can be reduced.

[0080] In one embodiment of the light emitting device, The third semiconductor layer may be provided between the AlN layer and the electrode.

[0081] According to this light emitting device, the flatness of the electrodes can be improved.

[0082] One aspect of the projector is The present invention has one aspect of the light emitting device. [Explanation of symbols]

[0083] 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, 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, 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... connected Continued part, 1070...first electrode, 1072...second electrode

Claims

1. 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.

2. 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.

3. In claim 2, The third semiconductor layer is provided between the AlN layer and the electrode.

4. A projector comprising the light emitting device according to claim 1 .

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