Light-emitting device and projector

Abstract

To provide a light-emitting device that can be reduced in size.SOLUTION: A light-emitting device has: a substrate; a laminate that is provided on the substrate; and a conductive layer that is provided on the laminate and injects current to the laminate. The laminate has a first semiconductor layer of a first conductivity type that is provided between the substrate and the conductive layer, a second semiconductor layer of a second conductivity type different from the first conductivity type, and a luminous layer that is provided between the first semiconductor layer and the second semiconductor layer. The conductive layer has a plurality of wire parts extending in a direction orthogonal to a lamination direction of the laminate, and deflects light generated in the luminous layer. The luminous layer is injected with current through the plurality of wire parts.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Since a liquid crystal projector requires polarized light to display an image, it is desirable for the light source for the liquid crystal projector to emit light with a high degree of polarization.

[0003] For example, Patent Document 1 describes a polarized light source that includes a light emitting element flip-chip connected to a lead portion and a polarizing plate attached to the side of the lead portion facing the light emitting element at the position of a window. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-72990 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the polarized light source described in Patent Document 1, the light emitting element and the polarizing plate are provided at a distance from each other, which results in an increase in size. [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; a conductive layer provided on the stacked body and configured to inject a current into the stacked body; and the laminate is provided between the substrate and the conductive layer, 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; and the conductive layer has a plurality of wire portions extending in a direction perpendicular to the stacking direction of the laminate, and polarizes the light generated in the light-emitting layer; A current is injected into the light-emitting layer via the plurality of wire portions.

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

[0008] [Figure 1] FIG. 1 is a cross-sectional view schematically showing a light emitting device according to a first embodiment. [Figure 2] FIG. 1 is a plan view schematically showing a light emitting device according to a first embodiment. [Figure 3] 3A to 3C are cross-sectional views schematically showing the manufacturing process of the light emitting device according to the first embodiment. [Figure 4] FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a second embodiment. [Figure 5] FIG. 10 is a plan view schematically showing a light emitting device according to a second embodiment. [Figure 6] 5A to 5C are cross-sectional views schematically showing the manufacturing process of the light emitting device according to the second embodiment. [Figure 7] FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a third embodiment. [Figure 8] FIG. 10 is a cross-sectional view schematically showing a light emitting device according to a fourth embodiment. [Figure 9] FIG. 10 is a diagram schematically showing a projector according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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 content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0010] 1. First embodiment 1.1. Light-emitting device First, a light emitting device according to a first embodiment will be described with reference to the drawings. Fig. 1 is a cross-sectional view schematically showing a light emitting device 100 according to the first embodiment. Fig. 2 is a plan view schematically showing the light emitting device 100 according to the first embodiment. Fig. 1 is a cross-sectional view taken along line II in Fig. 2. Figs. 1 and 2 show an X-axis, a Y-axis, and a Z-axis as three mutually orthogonal axes.

[0011] 1 and 2, the light emitting device 100 includes, for example, a substrate 10, a laminate 20, an insulating layer 40, an n-type electrode 50, a first p-type electrode 60, a wire-grid polarizer 70, wiring 80, and a pad 90. The light emitting device 100 is an LED (Light Emitting Diode).

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

[0013] The laminate 20 is provided on a substrate 10. In the example shown in Fig. 1, the laminate 20 is provided on the substrate 10. The laminate 20 is provided between the substrate 10 and a wire-grid polarizer 70. The laminate 20 includes, for example, a buffer layer 22, a first semiconductor layer 32, a light-emitting layer 34, and a second semiconductor layer 36.

[0014] In this specification, in the stacking direction of the stacked body 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." A direction perpendicular to the stacking direction is also referred to as an "in-plane direction." The "stacking direction of the stacked body 20" refers to the stacking direction of the first semiconductor layer 32 and the light emitting layer 34. In the illustrated example, the stacking direction is the Z-axis direction.

[0015] The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is provided between the substrate 10 and the first semiconductor layer 32. The buffer layer 22 is a semiconductor layer of a first conductivity type. The buffer layer 22 is, for example, an n-type GaN layer doped with Si.

[0016] 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.

[0017] 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, 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.

[0018] There is no particular limitation on the number of well layers and barrier layers that make up the light-emitting layer 34. For example, only one well layer may be provided, in which case the light-emitting layer 34 has an SQW (Single Quantum Well) structure.

[0019] 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.

[0020] 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.

[0021] In the light-emitting device 100, a p-type second semiconductor layer 36, an i-type light-emitting layer 34, and an n-type first semiconductor layer 32 form a p-i-n diode. In the light-emitting device 100, when a forward bias voltage of the p-i-n diode is applied between the n-type electrode 50 and the first p-type electrode 60, a current is injected into the light-emitting layer 34, causing recombination of electrons and holes in the light-emitting layer 34. This recombination generates light. The light generated in the light-emitting layer 34 passes through the first p-type electrode 60 and the wire-grid polarizer 70 and is emitted.

[0022] Although not shown, a reflective layer may be provided between the substrate 10 and the buffer layer 22 or below 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 first p-type electrode 60 side.

[0023] The insulating layer 40 is provided on the buffer layer 22. When viewed from the stacking direction, the insulating layer 40 surrounds the semiconductor layers 32 and 36 and the light-emitting layer 34. In the illustrated example, the upper surface of the insulating layer 40 is located in the +Z-axis direction further than the upper surface of the first p-type electrode 60, but the position of the upper surface of the insulating layer 40 is not particularly limited. The insulating layer 40 is, for example, a silicon oxide layer or a polyimide layer.

[0024] The n-type electrode 50 is provided on the buffer layer 22. The n-type electrode 50 may be in ohmic contact with the buffer layer 22. The n-type electrode 50 is electrically connected to the first semiconductor layer 32. In the illustrated example, the n-type electrode 50 is electrically connected to the first semiconductor layer 32 via the buffer layer 22. The n-type electrode 50 is one of the electrodes for injecting current into the light-emitting layer 34. The n-type electrode 50 may be, for example, an electrode formed by laminating a Cr layer, a Ni layer, and an Au layer in this order from the buffer layer 22 side. Although not illustrated, the insulating layer 40 has a contact hole for electrical connection with the n-type electrode 50.

[0025] The first p-type electrode 60 is provided on the second semiconductor layer 36. The first p-type electrode 60 is provided between the stacked body 20 and the wire-grid polarizer 70. The first p-type electrode 60 may be in ohmic contact with the second semiconductor layer 36.

[0026] The thickness of the first p-type electrode 60 is, for example, several tens of nanometers or less. If the thickness of the first p-type electrode 60 is several tens of nanometers or less, it is possible to reduce the loss of light generated in the light-emitting layer 34 when it passes through the first p-type electrode 60. The first p-type electrode 60 is the other electrode for injecting current into the light-emitting layer 34. As the first p-type electrode 60, for example, a Pd layer, a Pt layer, and an Au layer stacked in this order from the second semiconductor layer 36 side can be used.

[0027] The wire grid polarizer 70 is provided on the laminate 20. In the illustrated example, the wire grid polarizer 70 is provided on the laminate 20 via the first p-type electrode 60. The wire grid polarizer 70 is provided on the first p-type electrode 60. The wire grid polarizer 70 is in contact with the first p-type electrode 60. The wire grid polarizer 70 has a plurality of wire portions 72. The plurality of wire portions 72 extend in a direction perpendicular to the stacking direction. In the example illustrated in FIG. 2, the plurality of wire portions 72 extend in the Y-axis direction. The pitch of the plurality of wire portions 72 is, for example, half or less of the wavelength of light generated in the light-emitting layer 34. Specifically, the pitch of the plurality of wire portions 72 is 400 nm or less, preferably approximately 100 nm. The width of the wire portions 72 is, for example, 300 nm or less, preferably approximately 60 nm. In the illustrated example, the width of the wire portions 72 is the size of the wire portions 72 in the X-axis direction. The thickness of the wire portion 72 is greater than the thickness of the first p-type electrode 60. In the illustrated example, the thickness of the wire portion 72 is the size of the wire portion 72 in the Z-axis direction. The thickness of the wire portion 72 is, for example, more than twice the thickness of the first p-type electrode 60.

[0028] The wire grid polarizer 70 polarizes light generated in the light-emitting layer 34 by using the multiple wire portions 72. The wire grid polarizer 70 transmits, by using the multiple wire portions 72, light generated in the light-emitting layer 34 whose electric field oscillates in a direction perpendicular to the extension direction of the wire portions 72 (the X-axis direction in the illustrated example), and reflects other light (for example, light whose electric field oscillates in the Y-axis direction) toward the laminate 20. This allows the wire grid polarizer 70 to polarize the light generated in the light-emitting layer 34. The wire grid polarizer 70 allows the light-emitting device 100 to emit, for example, linearly polarized light whose electric field oscillates in the X-axis direction. The degree of polarization of the light emitted from the light-emitting device 100 can be controlled by adjusting the width, thickness, and pitch of the wire portions 72.

[0029] The wire grid polarizer 70 may be, for example, a reflective wire grid polarizer that reflects light whose electric field oscillates in the Y-axis direction toward the laminate 20, or an absorptive wire grid polarizer that absorbs light whose electric field oscillates in the Y-axis direction.

[0030] The wire portions 72 of the wire-grid polarizer 70 are conductive. The wire portions 72 contain metal. As shown in FIG. 1 , the wire portions 72 have, for example, a first layer 72a and a second layer 72b. The wire-grid polarizer 70 corresponds to the "conductive layer" referred to in the claims. The wire-grid polarizer 70 injects a current into the laminate 20.

[0031] The material of the first layer 72a of the wire portion 72 is, for example, Al, Ag, or an alloy thereof. If the first layer 72a is made of such a material, it can constitute a reflective wire-grid polarizer 70. The first layer 72a may be made of a material that contains Al and at least one of amorphous Si, amorphous Ge, and SiN. If the first layer 72a is made of such a material, it can constitute an absorptive wire-grid polarizer 70.

[0032] The second layer 72b of the wire portion 72 is provided between the first layer 72a and the first p-type electrode 60. The melting point of the second layer 72b is higher than the melting point of the first layer 72a. The material of the second layer 72b is, for example, Mo, Ti, TiN x , Ta, or an alloy of these with Al. The thickness of the second layer 72b is smaller than the thickness of the first layer 72a. The thickness of the second layer 72b is, for example, smaller than half the thickness of the first layer 72a.

[0033] As shown in FIG. 2 , the wire grid polarizer 70 has connection portions 74 that connect adjacent wire portions 72 among the plurality of wire portions 72. In the illustrated example, the connection portions 74 connect the ends of adjacent wire portions 72 in the +Y-axis direction. Furthermore, the connection portions 74 connect the ends of adjacent wire portions 72 in the −Y-axis direction. The connection portions 74 extend in the X-axis direction from one of the adjacent wire portions 72 to the other wire portion 72. The wire grid polarizer 70 has a shape in which slits extending in the Y-axis direction are formed in a plate-like member. In the illustrated example, when viewed from the stacking direction, the connection portions 74 do not overlap the first p-type electrode 60 but overlap the insulating layer 40. The material of the connection portions 74 is, for example, the same as that of the wire portions 72.

[0034] The wiring 80 connects the wire-grid polarizer 70 and the pad 90. In the illustrated example, the pad 90 is provided in the +Y-axis direction of the wire-grid polarizer 70. The wiring 80 extends from the pad 90 in the −Y-axis direction and is connected to the wire-grid polarizer 70. The size of the pad 90 in the X-axis direction is larger than the size of the wiring 80 in the X-axis direction. For example, a wire bond (not shown) is connected to the pad 90. A current flowing through the wire bond is injected into the light-emitting layer 34 via the pad 90, the wiring 80, the wire-grid polarizer 70, and the first p-type electrode 60. In this way, a current is injected into the light-emitting layer 34 via the multiple wire portions 72 and the first p-type electrode 60. The multiple wire portions 72 also function as electrodes for injecting a current into the light-emitting layer 34. The wiring 80 and the pad 90 are made of the same material as the wire portion 72, for example.

[0035] Although the above description has been given of an InGaN-based light emitting layer 34, various material systems that can emit 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.

[0036] The light emitting device 100 has the following advantages, for example.

[0037] The light emitting device 100 has a wire grid polarizer 70 provided on the laminate 20. Therefore, the light emitting device 100 can be made smaller than when the wire grid polarizer is not provided on the laminate.

[0038] Furthermore, in the light-emitting device 100, the wire-grid polarizer 70 has a plurality of wire portions 72 extending in a direction perpendicular to the stacking direction, and polarizes the light generated in the light-emitting layer 34. Therefore, the light-emitting device 100 can emit, for example, linearly polarized light.

[0039] Furthermore, in the light-emitting device 100, current is injected into the light-emitting layer 34 via the multiple wire portions 72. Therefore, in the light-emitting device 100, current also flows through the wire portions 72, compared to when no current flows through the wire portions, thereby achieving lower resistance. This allows current to be injected uniformly into the light-emitting layer 34. For example, the first p-type electrode 60 has a lower resistivity than the second p-type electrode 62, but is thinner. Therefore, if the wire portions 72 are not provided, it may be difficult to inject current uniformly into the light-emitting layer. Furthermore, light whose electric field oscillates in a direction perpendicular to the extension direction of the wire portions 72 is hardly absorbed by the multiple wire portions 72, and therefore, by increasing the thickness of the wire portions 72, further lower resistance can be achieved.

[0040] The light-emitting device 100 has a first p-type electrode 60 provided between the laminate 20 and the wire-grid polarizer 70, and the wire-grid polarizer 70 is in contact with the first p-type electrode 60. Light generated in the light-emitting layer 34 passes through the first p-type electrode 60 and is emitted, and a current is injected into the light-emitting layer 34 via the first p-type electrode 60. Therefore, the light-emitting device 100 can inject a current into the light-emitting layer 34 more uniformly than a device that does not have the first p-type electrode. Furthermore, the device can be made smaller than a device in which the wire-grid polarizer and the first p-type electrode are spaced apart.

[0041] In the light-emitting device 100, the wire-grid polarizer 70 has connection portions 74 that connect adjacent wire portions 72 among the plurality of wire portions 72. Therefore, in the light-emitting device 100, current can be passed through the plurality of wire portions 72 with better uniformity than in a case where the connection portions 74 are not provided.

[0042] In the light-emitting device 100, each of the multiple wire portions 72 has a first layer 72a and a second layer 72b that is provided between the first layer 72a and the laminate 20 and has a higher melting point than the first layer 72a. Therefore, in the light-emitting device 100, even if heat is generated when light generated in the light-emitting layer 34 passes through the wire-grid polarizer 70, the second layer 72b can prevent atoms contained in the first layer 72a from diffusing to the first p-type electrode 60 due to the heat. In particular, since Al atoms are easily diffused, it is preferable to provide the second layer 72b when the first layer 72a contains Al atoms.

[0043] 1.2. Light-emitting device manufacturing method Next, a method for manufacturing the light emitting device 100 according to the first embodiment will be described with reference to the drawings. Figure 3 is a cross-sectional view schematically showing the manufacturing process of the light emitting device 100 according to the first embodiment.

[0044] 3, a buffer layer 22 is epitaxially grown on a substrate 10. Examples of methods for epitaxial growth include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

[0045] 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 evaporation 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.

[0046] Next, using the mask layer as a mask, 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. Examples of the epitaxial growth method include MOCVD and MBE. Through this process, the stacked body 20 can be formed.

[0047] 1, an n-type electrode 50 is formed on the buffer layer 22. The n-type electrode 50 is formed by, for example, sputtering or vacuum deposition.

[0048] Next, the insulating layer 40 is formed on the buffer layer 22 and the n-type electrode 50. The insulating layer 40 is formed by, for example, a chemical vapor deposition (CVD) method, a spin coating method, or the like.

[0049] Next, the first p-type electrode 60 is formed on the second semiconductor layer 36. The first p-type electrode 60 is formed by, for example, sputtering, vacuum deposition, or the like.

[0050] Next, a conductive layer is formed on the first p-type electrode 60. The conductive layer is formed by, for example, sputtering or vacuum deposition. Next, a resist layer is formed on the conductive layer, and the resist layer is exposed and developed. After that, the conductive layer is dry-etched using the resist layer as a mask. The resist layer is then peeled off. The exposure is performed by, for example, two-beam interference exposure. The dry etching is performed using, for example, Cl2 gas, BCl3 gas, Cl4 gas, or a mixture of these gases. This process can form a wire grid polarizer 70 having wire portions 72 and connection portions 74. Furthermore, this process forms wiring 80 and pads 90.

[0051] Through the above steps, the light emitting device 100 can be manufactured.

[0052] 2. Second embodiment 2.1. Light-emitting device Next, a light emitting device 200 according to a second embodiment will be described with reference to the drawings. Fig. 4 is a cross-sectional view schematically showing the light emitting device 200 according to the second embodiment. Fig. 5 is a plan view schematically showing the light emitting device 200 according to the second embodiment. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 5.

[0053] Hereinafter, in the light emitting device 200 according to the second embodiment, components having the same functions as the components of the light emitting device 100 according to the first embodiment described above will be given the same reference numerals, and detailed description thereof will be omitted.

[0054] As shown in FIGS. 4 and 5, the light emitting device 200 differs from the above-described light emitting device 100 in that it has a second p-type electrode 62 and a third p-type electrode 64.

[0055] As shown in FIG. 4 , the second p-type electrode 62 is provided on the opposite side of the wire grid polarizer 70 from the first p-type electrode 60. The second p-type electrode 62 is provided on the plurality of wire portions 72. The second p-type electrode 62 is connected to the plurality of wire portions 72. The second p-type electrode 62 is provided across the plurality of wire portions 72. The second p-type electrode 62 is provided between the wire grid polarizer 70 and the third p-type electrode 64. The thickness of the second p-type electrode 62 is, for example, smaller than the thickness of the wire portions 72 and larger than the thickness of the first p-type electrode 60. The resistivity of the wire portions 72 and the resistivity of the first p-type electrode 60 are lower than the resistivity of the second p-type electrode 62. The second p-type electrode 62 is a transparent electrode that is transparent to the light generated in the light-emitting layer 34. The second p-type electrode 62 is, for example, an ITO (Indium Tin Oxide) layer, a ZnO layer, or the like.

[0056] The third p-type electrode 64 is provided on the second p-type electrode 62. Furthermore, the third p-type electrode 64 is provided on the insulating layer 40 and on a side surface of the insulating layer 40 that defines an opening 42 provided in the insulating layer 40. The thickness of the third p-type electrode 64 is, for example, smaller than the thickness of the wire portion 72 and larger than the thickness of the first p-type electrode 60. The material of the third p-type electrode 64 is, for example, the same as that of the second p-type electrode 62. In the example shown in FIG. 5, the shape of the third p-type electrode 64 is circular.

[0057] Although not shown, the wire portion 72 may have a third layer between the first layer 72a and the second p-type electrode 62, the third layer having a melting point higher than that of the first layer 72a. This prevents the Al contained in the first layer 72a from undergoing a battery reaction with the second p-type electrode 62, which is an ITO layer, and thus prevents the Al contained in the first layer 72a from melting. The material of the third layer is, for example, the same as that of the second layer 72b.

[0058] In the light emitting device 100 described above, as shown in FIG. 2, the wiring 80 connects the wire grid polarizer 70 and the pad 90. As shown in FIG.

[0059] 5 , in the light-emitting device 200, the wiring 80 connects the third p-type electrode 64 and the pad 90. The material of the wiring 80 and the material of the pad 90 are, for example, the same as those of the third p-type electrode 64. A current flowing through a bonding wire (not shown) connected to the pad 90 is injected into the light-emitting layer 34 via the pad 90, the wiring 80, the third p-type electrode 64, the second p-type electrode 62, the wire-grid polarizer 70, and the first p-type electrode 60.

[0060] The light emitting device 200 has the following advantages, for example.

[0061] The light emitting device 200 has a second p-type electrode 62 that is provided on the opposite side of the wire grid polarizer 70 from the first p-type electrode 60 and is connected to a plurality of wire portions 72. Therefore, in the light emitting device 200, the wire portions 72 can be protected by the second p-type electrode 62. Because the wire portions 72 are narrow, if the wire portions 72 are exposed, there is a possibility that the wire portions 72 will collapse due to contact with moisture or external components, for example, when forming the insulating layer 40 or when using the product. In the light emitting device 200, the wire portions 72 can be protected by the second p-type electrode 62, so the possibility of the wire portions 72 collapsing can be reduced.

[0062] In the light-emitting device 200, the second p-type electrode 62 is a transparent electrode that is transparent to the light generated in the light-emitting layer 34, and the resistivity of each of the multiple wire portions 72 is lower than the resistivity of the second p-type electrode 62. Therefore, in the light-emitting device 200, the current that has flowed through the second p-type electrode 62 can flow preferentially through the wire portion 72, which has a lower resistivity, in the portion that overlaps with the wire portion 72, and therefore, the current can be injected into the light-emitting layer 34 with better uniformity than in the case where the wire portion 72 is not provided.

[0063] 2.2. Light-emitting device manufacturing method Next, a method for manufacturing the light emitting device 200 according to the second embodiment will be described with reference to the drawings. Figure 6 is a cross-sectional view schematically showing the manufacturing process of the light emitting device 200 according to the second embodiment.

[0064] In the manufacturing method of the light emitting device 200, similarly to the manufacturing method of the light emitting device 100 described above, after forming the laminate 20, the first p-type electrode 60, and the wire grid polarizer 70, the second p-type electrode 62 is formed on the plurality of wire portions 72 as shown in Fig. 6. The second p-type electrode 62 is formed by, for example, a sputtering method or a vacuum deposition method. The second p-type electrode 62, the plurality of wire portions 72, and the first p-type electrode 60 may be etched all at once to form the second p-type electrode 62, the plurality of wire portions 72, and the first p-type electrode 60 in a predetermined shape.

[0065] 4, an n-type electrode 50 is formed on the buffer layer 22. The n-type electrode 50 is formed by, for example, sputtering or vacuum deposition.

[0066] Next, the insulating layer 40 is formed on the buffer layer 22 and the n-type electrode 50. The insulating layer 40 is formed by, for example, spin coating or CVD. Next, the insulating layer 40 is etched to form an opening 42.

[0067] Next, a third p-type electrode 64 is formed on the second p-type electrode 62, on the insulating layer 40, and on the side surfaces of the insulating layer 40 that define the opening 42. The third p-type electrode 64 is formed by, for example, sputtering or vacuum deposition. Furthermore, wiring 80 and pads 90 are formed by this process.

[0068] Through the above steps, the light emitting device 200 can be manufactured.

[0069] 3. Third embodiment 3.1. Light-emitting device Next, a light emitting device 300 according to a third embodiment will be described with reference to the drawings. Fig. 7 is a cross-sectional view schematically showing the light emitting device 300 according to the third embodiment.

[0070] Hereinafter, in the light emitting device 300 according to the third embodiment, components having the same functions as the components of the light emitting device 100 according to the first embodiment described above will be given the same reference numerals, and detailed description thereof will be omitted.

[0071] 7, the light emitting device 300 differs from the above-described light emitting device 100 in that the stacked body 20 has a photonic crystal structure 38. In the illustrated example, the second semiconductor layer 36 has the photonic crystal structure 38.

[0072] The second semiconductor layer 36 constitutes a photonic crystal structure 38. The photonic crystal structure 38 exhibits a photonic crystal effect, and confines the light generated in the light emitting layer 34 in the in-plane direction and emits it in the stacking direction.

[0073] In the illustrated example, a plurality of holes 37 are provided in the second semiconductor layer 36, and the holes 37 and portions 36a of the second semiconductor layer 36 located in the in-plane direction of the holes 37 form a photonic crystal structure 38. The difference in refractive index between the portions 36a of the second semiconductor layer 36 and the holes 37 produces a photonic crystal effect. Although not illustrated, the holes 37 may be filled with a silicon oxide layer or the like. The diameter of the holes 37 is, for example, 50 nm or more and 500 nm or less.

[0074] Note that the "diameter of the hole" refers to the diameter when the planar shape of the hole 37 is circular, and refers to the diameter of the smallest encompassing circle when the planar shape of the hole 37 is not circular. For example, when the planar shape of the hole 37 is polygonal, the diameter of the smallest circle that includes the polygon inside, and when the planar shape of the hole 37 is elliptical, the diameter of the smallest circle that includes the ellipse inside. The same applies to the "diameter of the columnar portion" described below.

[0075] The holes 37 are arranged in a predetermined direction at a predetermined pitch when viewed from the stacking direction. The holes 37 are arranged, for example, in a triangular lattice pattern. The arrangement of the holes 37 is not particularly limited, and they may be arranged in a square lattice pattern.

[0076] The "hole pitch" refers to the distance between the centers of adjacent holes 37 along a predetermined direction. If the planar shape of the holes 37 is a circle, the "hole center" refers to the center of the circle. If the planar shape of the holes 37 is not a circle, the "hole center" refers to the center of the smallest encompassing circle. For example, if the planar shape of the holes 37 is a polygon, the center of the hole 37 is the center of the smallest circle that contains the polygon. If the planar shape of the holes 37 is an ellipse, the center of the smallest circle that contains the ellipse. The same applies to the "diameter of the columnar portion" described below.

[0077] In the light-emitting device 300, light generated in the light-emitting layer 34 propagates in the in-plane direction, forms standing waves due to the photonic crystal effect of the multiple holes 37, and receives gain in the light-emitting layer 34 to produce laser oscillation. The light-emitting device 300 then emits the +1st-order diffracted light and the -1st-order diffracted light as laser light in the stacking direction. The light-emitting device 300 is a semiconductor laser that emits laser light.

[0078] Of the light emitted from the photonic crystal structure 38 in the stacking direction, the proportion of light whose electric field oscillates in a direction perpendicular to the extension direction of the wire portions 72 is greater than the proportion of light whose electric field oscillates in the extension direction of the wire portions 72. The oscillation direction of the electric field of the light emitted from the photonic crystal structure 38 in the stacking direction can be controlled by the pitch, shape, and size of the holes 37.

[0079] The light emitting device 300 has the following features, for example.

[0080] In the light-emitting device 300, the stack 20 has a photonic crystal structure 38 that confines light generated in the light-emitting layer 34 in the in-plane direction of the substrate 10 and emits it in the stacking direction. Therefore, the light-emitting device 300 can emit laser light in the stacking direction.

[0081] In the light emitting device 300, of the light emitted from the photonic crystal structure 38 in the stacking direction, the proportion of light whose electric field oscillates in a direction perpendicular to the extension direction of each of the plurality of wire portions 72 is greater than the proportion of light whose electric field oscillates in the extension direction of each of the plurality of wire portions 72. The wire grid polarizer 70 transmits light whose electric field oscillates in a direction perpendicular to the extension direction of the wire portions 72. Therefore, the light utilization efficiency can be improved compared to when the proportion of light whose electric field oscillates in a direction perpendicular to the extension direction of the wire portions is smaller than the proportion of light whose electric field oscillates in the extension direction of the wire portions.

[0082] In the light emitting device 300, the second semiconductor layer 36 constitutes a photonic crystal structure 38. In the light emitting device 300, the photonic crystal structure 38 can be constituted by, for example, forming a plurality of holes 37 in the second semiconductor layer 36.

[0083] Although not shown, the second semiconductor layer 36 may have a base provided on the light emitting layer 34 and a plurality of columnar portions protruding upward from the base, and the plurality of columnar portions may constitute the photonic crystal structure 38. The plurality of columnar portions may be formed, for example, by a method similar to that used for the plurality of columnar portions of the light emitting device according to the fourth embodiment described below.

[0084] 3.2. Light-emitting device manufacturing method Next, a method for manufacturing the light emitting device 300 according to the third embodiment will be described with reference to the drawings.

[0085] The method for manufacturing the light emitting device 300 is basically the same as the method for manufacturing the light emitting device 100 described above, except that a plurality of holes 37 are formed in the second semiconductor layer 36 by, for example, electron beam lithography and dry etching, as shown in Fig. 7. Therefore, detailed description thereof will be omitted.

[0086] 4. Fourth embodiment 4.1. Light-emitting device Next, a light emitting device 400 according to a fourth embodiment will be described with reference to the drawings. Fig. 8 is a cross-sectional view schematically showing the light emitting device 400 according to the fourth embodiment.

[0087] 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, the light emitting device 200 according to the second embodiment, and the light emitting device 300 according to the third embodiment described above will be given the same reference numerals, and detailed descriptions thereof will be omitted.

[0088] In the light emitting device 300 described above, the second semiconductor layer 36 constitutes the photonic crystal structure 38, as shown in FIG.

[0089] In contrast, in the light emitting device 400, the plurality of columns 30 form a photonic crystal structure 38, as shown in FIG.

[0090] The stacked body 20 has a plurality of columnar sections 30. The first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 constitute the plurality of columnar sections 30. A mask layer (not shown) for forming the columnar sections 30 is provided on the buffer layer 22. The mask layer is, for example, a titanium layer, a titanium oxide layer, a silicon layer, or a silicon oxide layer.

[0091] The columnar portion 30 is provided on the buffer layer 22. The columnar portion 30 has a columnar shape that protrudes upward from the buffer layer 22. In other words, the columnar portion 30 protrudes from the substrate 10 via the buffer layer 22. The columnar portion 30 is also called, for example, a nanocolumn, a nanowire, a nanorod, or a nanopillar. The planar shape of the columnar portion 30 is, for example, a polygon such as a regular hexagon, or a circle.

[0092] The diameter of the columnar section 30 is, for example, 50 nm or more and 500 nm or less. By setting the diameter of the columnar section 30 to 500 nm or less, it is possible to obtain a light-emitting layer 34 with high-quality crystals and reduce strain inherent in the light-emitting layer 34. This allows the light generated in the light-emitting layer 34 to be amplified with high efficiency.

[0093] 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 in a predetermined direction at a predetermined pitch when viewed from the stacking direction. The plurality of columnar sections 30 are arranged, for example, in a triangular lattice pattern. The arrangement of the plurality of columnar sections 30 is not particularly limited, and they may also be arranged in a square lattice pattern.

[0094] The multiple columnar portions 30 can exhibit the effect of a photonic crystal. Light generated in the light-emitting layer 34 propagates in the in-plane direction, forms standing waves due to the photonic crystal effect of the multiple columnar portions 30, receives gain in the light-emitting layer 34, and undergoes laser oscillation. The light-emitting device 300 then emits the +1st-order diffracted light and the -1st-order diffracted light as laser light in the stacking direction. The light-emitting device 400 is a semiconductor laser that emits laser light. The pitch of the multiple columnar portions 30 may be larger or smaller than the pitch of the multiple wire portions 72.

[0095] When viewed from the stacking direction, each of the multiple columnar portions 30 overlaps with one or more of the multiple wire portions 72. When viewed from the stacking direction, each of the multiple columnar portions 30 may overlap with only one wire portion 72, or may overlap with two or more wire portions 72. When viewed from the stacking direction, there is no columnar portion 30 among the multiple columnar portions 30 that does not overlap with a wire portion 72.

[0096] Similar to the above-described light-emitting device 200, the light-emitting device 400 has a second p-type electrode 62 and a third p-type electrode 64. Although not shown in Fig. 8, a wiring 80 connects the third p-type electrode 64 and a pad 90, similar to the above-described light-emitting device 200.

[0097] In the above example, a gap is provided between the adjacent columnar sections 30, but a light propagation layer that propagates light generated in the light-emitting layer 34 may be provided between the adjacent columnar sections 30. The light propagation layer may be a silicon oxide layer.

[0098] Furthermore, the light emitting device 400 may be an LED instead of a semiconductor laser.

[0099] The light emitting device 400 has the following advantages, for example.

[0100] In the light emitting device 400, the stacked body 20 has a plurality of columnar sections 30, and the first semiconductor layer 32, the second semiconductor layer 36, and the light emitting layer 34 form the plurality of columnar sections 30, which form a photonic crystal structure 38. Therefore, in the light emitting device 400, a light emitting layer 34 of high quality crystal can be obtained, and strain inherent in the light emitting layer 34 can be reduced.

[0101] In the light emitting device 400, when viewed from the stacking direction, each of the multiple columnar portions 30 overlaps with one or more of the multiple wire portions 72. Therefore, in the light emitting device 400, current can be injected into the columnar portions 30 with good uniformity compared to when there are columnar portions that do not overlap with wire portions when viewed from the stacking direction.

[0102] 4.2. Light-emitting device manufacturing method Next, a method for manufacturing the light emitting device 400 according to the fourth embodiment will be described with reference to the drawings.

[0103] In the manufacturing method of the light emitting device 400, similar to the manufacturing method of the light emitting device 100 described above, after forming the buffer layer 22, a mask layer (not shown) is formed on the buffer layer 22. The mask layer is formed by film formation using, for example, an electron beam evaporation method or a plasma CVD method, and patterning. The patterning is performed by electron beam lithography and dry etching.

[0104] 8, 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. Examples of methods for epitaxial growth include MOCVD and MBE. This process allows the formation of multiple columnar sections 30.

[0105] Thereafter, in the manufacturing method of the light emitting device 400, a first p-type electrode 60, a wire grid polarizer 70, a second p-type electrode 62, an n-type electrode 50, an insulating layer 40, and a third p-type electrode 64 are formed, similar to the manufacturing method of the light emitting device 200 described above.

[0106] Through the above steps, the light emitting device 400 can be manufactured.

[0107] 5. Fifth embodiment Next, a projector according to a fifth embodiment will be described with reference to the drawings. Fig. 9 is a diagram schematically showing a projector 800 according to the fifth embodiment.

[0108] The projector 800 includes, for example, a light emitting device 100 as a light source.

[0109] Projector 800 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. 9.

[0110] The projector 800 further includes, within the housing, a first optical element 802R, a second optical element 802G, a third optical element 802B, a first light modulation device 804R, a second light modulation device 804G, a third light modulation device 804B, and a projection device 808. The first light modulation device 804R, the second light modulation device 804G, and the third light modulation device 804B are, for example, transmissive liquid crystal light valves. The projection device 808 is, for example, a projection lens.

[0111] Light emitted from red light source 100R is incident on first optical element 802R. The light emitted from red light source 100R is collected by first optical element 802R. Note that first optical element 802R may have a function other than collecting light. The same applies to second optical element 802G and third optical element 802B, which will be described later.

[0112] The light collected by the first optical element 802R is incident on the first light modulation device 804R. The first light modulation device 804R modulates the incident light in accordance with image information. The projection device 808 then enlarges the image formed by the first light modulation device 804R and projects it onto a screen 810.

[0113] The light emitted from green light source 100G is incident on second optical element 802G. The light emitted from green light source 100G is collected by second optical element 802G.

[0114] The light collected by the second optical element 802G is incident on the second light modulation device 804G. The second light modulation device 804G modulates the incident light in accordance with image information. The projection device 808 then enlarges the image formed by the second light modulation device 804G and projects it onto the screen 810.

[0115] The light emitted from blue light source 100B is incident on third optical element 802B. The light emitted from blue light source 100B is collected by third optical element 802B.

[0116] The light collected by the third optical element 802B enters the third light modulation device 804B. The third light modulation device 804B modulates the incident light in accordance with image information. The projection device 808 then enlarges the image formed by the third light modulation device 804B and projects it onto the screen 810.

[0117] The projector 800 may also have a cross dichroic prism 806 that combines the light emitted from the first light modulation device 804R, the second light modulation device 804G, and the third light modulation device 804B and guides the combined light to the projection device 808.

[0118] The three colored lights modulated by the first light modulation device 804R, the second light modulation device 804G, and the third light modulation device 804B enter the cross dichroic prism 806. The cross dichroic prism 806 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. These dielectric multilayer films combine the three colored lights to form light that represents a color image. The combined light is then projected onto a screen 810 by a projection device 808, and an enlarged image is displayed.

[0119] 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 804R, second light modulation device 804G, and third light modulation device 804B, by controlling light emitting device 100 as pixels of the image in accordance with image information. Then, projection device 808 may enlarge and project the image formed by red light source 100R, green light source 100G, and blue light source 100B onto screen 810.

[0120] In the above example, a transmissive liquid crystal light valve is used as the light modulation device, but a light valve other than a liquid crystal light valve or a reflective light valve may also be used. Examples of such light valves include a reflective liquid crystal light valve and a digital micromirror device. The configuration of the projection device can be changed as appropriate depending on the type of light valve used.

[0121] 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.

[0122] The above-described embodiment and modifications are merely examples, and the present invention is not limited to these. For example, the embodiments and modifications can be combined as appropriate.

[0123] 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 that replace non-essential parts of the configurations described in the embodiments. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations that add publicly known technology to the configurations described in the embodiments.

[0124] The following can be derived from the above-described embodiment and modifications.

[0125] One aspect of the light emitting device is A substrate; a laminate provided on the substrate; a conductive layer provided on the stacked body and configured to inject a current into the stacked body; and the laminate is provided between the substrate and the conductive layer, 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; and the conductive layer has a plurality of wire portions extending in a direction perpendicular to the stacking direction of the laminate, and polarizes the light generated in the light-emitting layer; A current is injected into the light-emitting layer via the plurality of wire portions.

[0126] This light emitting device can be made smaller.

[0127] In one embodiment of the light emitting device, a first electrode provided between the laminate and the conductive layer; the conductive layer is in contact with the first electrode, The light generated in the light-emitting layer is transmitted through the first electrode and emitted. A current may be injected into the light-emitting layer via the first electrode.

[0128] According to this light emitting device, a current can be injected into the light emitting layer with good uniformity.

[0129] In one embodiment of the light emitting device, The conductive layer may have a second electrode provided on the opposite side to the first electrode and connected to the plurality of wire portions.

[0130] According to this light emitting device, the wire portion can be protected by the second electrode.

[0131] In one embodiment of the light emitting device, the second electrode is a transparent electrode that is transparent to the light generated in the light-emitting layer, The resistivity of each of the plurality of wire portions may be lower than the resistivity of the second electrode.

[0132] According to this light emitting device, a current can be injected into the light emitting layer with good uniformity.

[0133] In one embodiment of the light emitting device, The stack may have a photonic crystal structure that confines light generated in the light-emitting layer in a direction perpendicular to the stacking direction and emits the light in the stacking direction.

[0134] This light emitting device can emit laser light in the stacking direction, for example.

[0135] In one embodiment of the light emitting device, Of the light emitted from the photonic crystal structure in the stacking direction, the proportion of light whose electric field oscillates in a direction perpendicular to the extension direction of each of the plurality of wire portions may be greater than the proportion of light whose electric field oscillates in the extension direction of each of the plurality of wire portions.

[0136] This light emitting device can improve the light utilization efficiency.

[0137] In one embodiment of the light emitting device, The second semiconductor layer may constitute the photonic crystal structure.

[0138] According to this light emitting device, for example, a photonic crystal structure can be configured by forming a plurality of holes in the second semiconductor layer.

[0139] In one embodiment of the light emitting device, The laminate has a plurality of columnar portions, the first semiconductor layer, the second semiconductor layer, and the light emitting layer constitute the plurality of columnar portions; The plurality of columns may constitute the photonic crystal structure.

[0140] According to this light emitting device, a light emitting layer of high quality crystal can be obtained, and strain inherent in the light emitting layer can be reduced.

[0141] In one embodiment of the light emitting device, When viewed from the stacking direction, the plurality of columnar portions may overlap one or more of the plurality of wire portions.

[0142] According to this light emitting device, current can be injected into the columnar portion with good uniformity.

[0143] In one embodiment of the light emitting device, The conductive layer may have a connection portion that connects adjacent wire portions of the plurality of wire portions.

[0144] According to this light emitting device, current can be passed through the plurality of wire portions with good uniformity.

[0145] In one embodiment of the light emitting device, Each of the plurality of wire portions is The first layer and a second layer provided between the first layer and the laminate and having a melting point higher than that of the first layer; may have

[0146] According to this light emitting device, the second layer can prevent atoms contained in the first layer from diffusing into the first electrode.

[0147] One aspect of the projector is The light emitting device has one aspect. [Explanation of symbols]

[0148] 10...substrate, 20...laminated body, 22...buffer layer, 30...columnar portion, 32...first semiconductor layer, 34...light-emitting layer, 36...second semiconductor layer, 36a...portion, 37...hole, 38...photonic crystal structure, 40...insulating layer, 42...opening, 50...n-type electrode, 60...first p-type electrode, 62...second p-type electrode, 64...third p-type electrode, 70...wire grid polarizer, 72...wire portion, 72a...first layer, 7 2b...second layer, 74...connection portion, 80...wiring, 90...pad, 100, 200, 300, 400...light-emitting device, 800...projector, 802R...first optical element, 802G...second optical element, 802B...third optical element, 804R...first light modulation device, 804G...second light modulation device, 804B...third light modulation device, 806...cross dichroic prism, 808...projection device, 810...screen

Claims

1. A substrate; a laminate; a conductive layer for injecting a current into the laminate; a first electrode provided between the laminate and the conductive layer and in contact with the conductive layer; and the laminate is provided between the substrate and the conductive layer, 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; and the conductive layer has a plurality of wire portions extending in a direction perpendicular to the stacking direction of the laminate and a connection portion connecting ends of adjacent wire portions among the plurality of wire portions, and polarizes light generated in the light-emitting layer; a current is injected into the light-emitting layer via the plurality of wire portions and the first electrode; The light generated in the light-emitting layer is transmitted through the first electrode and emitted. the connection portion is provided in a region other than a region in which the first electrode is provided in a plan view; Light-emitting device.

2. In claim 1, a second electrode provided on the conductive layer on the opposite side to the first electrode and connected to the plurality of wire portions;

3. In claim 2, the second electrode is a transparent electrode that is transparent to light generated in the light-emitting layer, A light emitting device, wherein the resistivity of each of the plurality of wire portions is lower than the resistivity of the second electrode.

4. In any one of claims 1 to 3, the laminate confines light generated in the light-emitting layer in a direction perpendicular to the lamination direction, A light-emitting device having a photonic crystal structure that emits light in the stacking direction.

5. In claim 4, A light-emitting device, wherein, of the light emitted from the photonic crystal structure in the stacking direction, the proportion of light whose electric field oscillates in a direction perpendicular to the extension direction of each of the plurality of wire portions is greater than the proportion of light whose electric field oscillates in the extension direction of each of the plurality of wire portions.

6. In claim 4 or 5, The second semiconductor layer constitutes the photonic crystal structure.

7. In claim 4 or 5, The laminate has a plurality of columnar portions, the first semiconductor layer, the second semiconductor layer, and the light emitting layer constitute the plurality of columnar portions, The plurality of pillars constitute the photonic crystal structure.

8. In claim 7, When viewed from the stacking direction, the plurality of columnar portions overlap one or more of the plurality of wire portions.

9. In any one of claims 1 to 8, Each of the plurality of wire portions is The first layer, a second layer provided between the first layer and the laminate and having a melting point higher than that of the first layer; A light emitting device comprising:

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

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