Light emission device, three-dimensional molding apparatus, and head-mounted display

Abstract

To provide an optical device that can inject electric current uniformly into a light-emitting layer.SOLUTION: A light emission device includes: a first multilayer film mirror consisting of multiple semiconductor layers that has a first conductive type; a second multilayer film mirror; a light-emitting layer provided between the first multilayer film mirror and the second multilayer film mirror; a GaN-based semiconductor layer which is provided between the light-emitting layer and the second multilayer film mirror and has a second conductive type that is different from the first conductive type; a semiconductor layer which has a first portion provided between the GaN-based semiconductor layer and the second multilayer film mirror and a second portion that does not overlap the second multilayer film mirror when viewed from the lamination direction of the first multilayer film mirror and the light-emitting layer and which has the second conductive type; and an electrode which is provided in the second portion. The material constituting the semiconductor layer that has the second conductive type is larger than a band gap of the material constituting the light-emitting layer and smaller than the band gap of the material constituting the GaN-based semiconductor layer.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light-emitting device, a three-dimensional modeling device, and a head-mounted display. [Background technology]

[0002] Vertical cavity surface emitting lasers (VCSELs) that emit light in a direction perpendicular to a substrate surface are known.

[0003] For example, Patent Document 1 describes a VCSEL that includes a lower DBR layer, an upper DBR, an active layer provided between the lower DBR layer and the upper DBR, a p-type semiconductor layer provided between the active layer and the upper DBR layer, and an electrode provided on the p-type semiconductor layer. In Patent Document 1, the upper DBR is provided in the center of the p-type semiconductor layer, and the electrode is provided at an end of the p-type semiconductor layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-72118 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned VCSEL, when emitting blue or green laser light, a GaN-based semiconductor material is used. However, since the p-type semiconductor layer made of a GaN-based semiconductor material has a high resistivity, it is difficult for the current injected from the electrode to be injected into the center of the active layer. [Means for solving the problem]

[0006] One aspect of the light emitting device according to the present invention is a first multilayer mirror including a plurality of semiconductor layers having a first conductivity type; A second multilayer mirror; and a light emitting layer provided between the first multilayer mirror and the second multilayer mirror; a GaN-based semiconductor layer having a second conductivity type different from the first conductivity type, the GaN-based semiconductor layer being provided between the light emitting layer and the second multilayer mirror; a semiconductor layer having the second conductivity type, the semiconductor layer including a first portion provided between the GaN-based semiconductor layer and the second multilayer mirror, and a second portion not overlapping with the second multilayer mirror as viewed in a stacking direction of the first multilayer mirror and the light emitting layer; An electrode provided in the second portion; having The material constituting the semiconductor layer having the second conductivity type has a band gap larger than that of the material constituting the light emitting layer and smaller than that of the material constituting the GaN-based semiconductor layer.

[0007] One aspect of the three-dimensional printing apparatus according to the present invention is to The present invention has one aspect of the light emitting device.

[0008] One aspect of the head mounted display according to the present invention is The present invention has one aspect of the light emitting device. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view illustrating a light emitting device according to an embodiment of the present invention. [Diagram 2] 5A to 5C are cross-sectional views each showing a schematic process for manufacturing the light emitting device according to the embodiment. [Diagram 3] FIG. 4 is a cross-sectional view illustrating a light emitting device according to a first modified example of the embodiment. [Figure 4] FIG. 11 is a cross-sectional view illustrating a light emitting device according to a second modified example of the embodiment. [Diagram 5] FIG. 1 is a diagram illustrating a three-dimensional printing apparatus according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram illustrating a light source of the three-dimensional printing apparatus according to the embodiment. [Figure 7] FIG. 11 is a diagram illustrating a three-dimensional modeling apparatus according to a modified example of the embodiment. [Figure 8] FIG. 1 is a perspective view showing a schematic diagram of a head mounted display according to an embodiment of the present invention. [Figure 9] FIG. 2 is a diagram for explaining an optical system of the head mounted display according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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.

[0011] 1. Light-emitting device Configuration 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.

[0012] 1, the light emitting device 100 includes, for example, a substrate 10, a first multilayer mirror 20, a light emitting layer 30, a GaN-based semiconductor layer 40, an insulating layer 50, a semiconductor layer 60, a second multilayer mirror 70, a first electrode 80, and a second electrode 82. The light emitting device 100 is, for example, a VCSEL that emits blue light and green light.

[0013] The substrate 10 has, for example, a first conductivity type. The first conductivity type is, for example, an n-type. The substrate 10 is, for example, an n-type GaN substrate doped with Si.

[0014] The first multilayer mirror 20 is provided on the substrate 10. The first multilayer mirror 20 is provided between the substrate 10 and the light emitting layer 30. The first multilayer mirror 20 is made of a plurality of semiconductor layers 22. The plurality of semiconductor layers 22 have, for example, n-type. The plurality of semiconductor layers 22 are composed of a high refractive index layer and a low refractive index layer having a lower refractive index than the high refractive index layer. The first multilayer mirror 20 is a DBR (Distributed Bragg Reflector) in which high refractive index layers and low refractive index layers are alternately stacked. The high refractive index layer is, for example, an n-type GaN layer doped with Si. The low refractive index layer is, for example, an n-type InAlN layer doped with Si (for example, In 0.18 Al 0.82 The number of the semiconductor layers 22 is not particularly limited.

[0015] In this specification, in the stacking direction (hereinafter simply referred to as the "stacking direction") between the first multilayer mirror 20 and the light emitting layer 30, when the light emitting layer 30 is used as a reference, the direction from the light emitting layer 30 toward the second multilayer mirror 70 is referred to as "upper", and the direction from the light emitting layer 30 toward the first multilayer mirror 20 is referred to as "lower". The direction perpendicular to the stacking direction is also referred to as the "in-plane direction".

[0016] The light emitting layer 30 is provided on the first multilayer mirror 20. The light emitting layer 30 is provided between the first multilayer mirror 20 and the second multilayer mirror 70. In the illustrated example, the light emitting layer 30 is provided between the first multilayer mirror 20 and the GaN-based semiconductor layer 40. The light emitting layer 30 generates light when a current is injected into it. The light emitting layer 30 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 30 has an MQW (Multiple Quantum Well) structure composed of a well layer and a barrier layer.

[0017] There is no particular limitation on the number of well layers and barrier layers constituting the light emitting layer 30. For example, only one well layer may be provided, in which case the light emitting layer 30 has a single quantum well (SQW) structure.

[0018] The GaN-based semiconductor layer 40 is provided on the light emitting layer 30. The GaN-based semiconductor layer 40 is provided between the light emitting layer 30 and the second multilayer mirror 70. In the illustrated example, the GaN-based semiconductor layer 40 is provided between the light emitting layer 30 and the semiconductor layer 60. The GaN-based semiconductor layer 40 has a second conductivity type different from the first conductivity type. The second conductivity type is, for example, p-type. The GaN-based semiconductor layer 40 is a semiconductor layer containing Ga and N. The GaN-based semiconductor layer 40 is a p-type GaN layer doped with Mg. The GaN-based semiconductor layer 40 may be an InGaN layer or an AlGaN layer.

[0019] The insulating layer 50 is provided on the GaN-based semiconductor layer 40. The insulating layer 50 is provided between the GaN-based semiconductor layer 40 and the semiconductor layer 60. The insulating layer 50 is, for example, a silicon oxide layer (SiO2 layer). An opening 52 is formed in the insulating layer 50. The opening 52 overlaps with the second multilayer mirror 70 when viewed from the stacking direction. The insulating layer 50 does not overlap with the second multilayer mirror 70 when viewed from the stacking direction, for example. The current injected into the light-emitting layer 30 by the first electrode 80 and the second electrode 82 flows through the opening 52. The insulating layer 50 is a current confinement layer.

[0020] The semiconductor layer 60 is provided on the GaN-based semiconductor layer 40 and the insulating layer 50. The semiconductor layer 60 has a first portion 62 and a second portion 64.

[0021] The first portion 62 of the semiconductor layer 60 is provided between the GaN-based semiconductor layer 40 and the second multilayer mirror 70. The opening 52 is filled with the first portion 62. The refractive index of the semiconductor layer 60 is higher than the refractive index of the insulating layer 50. Therefore, the light generated in the light emitting layer 30 can be confined in the first portion 62 that overlaps with the second multilayer mirror 70 when viewed from the stacking direction. In the illustrated example, the thickness of the first portion 62 is greater than the thickness of the GaN-based semiconductor layer 40.

[0022] When the second multilayer mirror 70 is larger than the opening 52 as viewed in the stacking direction, the opening of the second electrode 82 becomes larger accordingly, which may make it difficult to inject a current to the inside of the light-emitting layer (resistance increases). However, the second multilayer mirror can also function as a reflective film for light that is confined in the first portion 62 and seeps into the insulating layer 50. That is, due to a trade-off between resistance and light confinement, it is possible to select, for example, a second multilayer mirror 70 that is slightly larger (smaller) than the insulating layer 50 (up to about 2 um).

[0023] The second portion 64 of the semiconductor layer 60 is continuous with the first portion 62. The second portion 64 is provided at a position not overlapping with the second multilayer mirror 70 when viewed from the stacking direction. The second portion 64 is provided between the insulating layer 50 and the second electrode 82. In the illustrated example, the thickness of the second portion 64 is smaller than the thickness of the first portion 62.

[0024] The semiconductor layer 60 has a p-type conductivity. The semiconductor layer 60 is, for example, a SiC layer. The semiconductor layer 60 has a thermal energy activation value of, for example, 1×10 18 cm -3The semiconductor layer 60 has an impurity concentration of at least 1000 . The semiconductor layer 60 can have a higher impurity concentration than the GaN-based semiconductor layer 40. The resistivity of the semiconductor layer 60 is lower than the resistivity of the GaN-based semiconductor layer 40. The semiconductor layer 60 is larger than the band gap of the material constituting the light emitting layer 30 and smaller than the band gap of the material constituting the GaN-based semiconductor layer 40. The difference between the band gap of the material constituting the light emitting layer 30 and the band gap of the semiconductor layer 60 may be larger than the difference between the band gap of the semiconductor layer 60 and the band gap of the material constituting the GaN-based semiconductor layer 40.

[0025] The semiconductor layer 60 is made of, for example, 4H-SiC. The semiconductor layer 60 may contain 4H-SiC at a content of 90 mass% or more, preferably 95 mass% or more, and more preferably 99 mass% or more, with SiC of another crystal structure making up the remaining content. Examples of SiC with another crystal structure include 6H-SiC and 3C-SiC. The crystal structure of the semiconductor layer 60 is identified by, for example, X-ray diffraction.

[0026] The second multilayer mirror 70 is provided on the first portion 62 of the semiconductor layer 60. The second multilayer mirror 70 is made of, for example, a plurality of dielectric layers 72. The plurality of dielectric layers 72 are composed of high refractive index layers and low refractive index layers having a refractive index lower than that of the high refractive index layers. The second multilayer mirror 70 is a DBR in which high refractive index layers and low refractive index layers are alternately stacked. The high refractive index layers are, for example, Nb2O5 layers. The low refractive index layers are, for example, SiO2 layers. The number of the plurality of dielectric layers 72 is not particularly limited.

[0027] The first electrode 80 is provided under the substrate 10. The substrate 10 is provided between the first electrode 80 and the first multilayer mirror 20. The substrate 10 may be in ohmic contact with the first electrode 80. The first electrode 80 is electrically connected to the first multilayer mirror 20 via the substrate 10. As the first electrode 80, for example, a layer formed by laminating a Ti layer, an Au layer, a Pt layer, and an Au layer in this order from the substrate 10 side is used. The first electrode 80 is one of the electrodes for injecting a current into the light-emitting layer 30.

[0028] The second electrode 82 is provided on the second portion 64 of the semiconductor layer 60. The second portion 64 may be in ohmic contact with the second electrode 82. In the illustrated example, the second electrode 82 is separated from the second multilayer mirror 70. The second electrode 82 surrounds, for example, the second multilayer mirror 70 when viewed from the stacking direction. The second electrode 82 is electrically connected to the GaN-based semiconductor layer 40 via the semiconductor layer 60. For example, the second electrode 82 is formed by stacking a Ti layer, an Al layer, and an Au layer in this order from the semiconductor layer 60 side. The second electrode 82 is the other electrode for injecting a current into the light-emitting layer 30.

[0029] 1.2. Operation In the light emitting device 100, a pin diode is formed by the p-type GaN-based semiconductor layer 40, the i-type light emitting layer 30, and the n-type first multilayer mirror 20. In the light emitting device 100, when a forward bias voltage of the pin diode is applied between the first electrode 80 and the second electrode 82, a current is injected into the light emitting layer 30, and recombination of electrons and holes occurs in the light emitting layer 30. This recombination causes light emission. The light generated in the light emitting layer 30 is multiple-reflected between the first multilayer mirror 20 and the second multilayer mirror 70 to form a standing wave, and receives gain in the light emitting layer 30 to oscillate as a laser. Then, the light emitting device 100 emits laser light in the stacking direction from the second multilayer mirror 70 side.

[0030] 1.3. Effects The light emitting device 100 includes a first multilayer mirror 20 including a plurality of semiconductor layers 22 having a first conductivity type, a second multilayer mirror 70, a light emitting layer 30 provided between the first multilayer mirror 20 and the second multilayer mirror 70, and a GaN-based semiconductor layer 40 having a second conductivity type different from the first conductivity type and provided between the light emitting layer 30 and the second multilayer mirror 70. The light emitting device 100 further includes a first portion 62 provided between the GaN-based semiconductor layer 40 and the second multilayer mirror 70, and a second portion 64 not overlapping with the second multilayer mirror 70 as viewed from the stacking direction, and includes a semiconductor layer 60 having the second conductivity type and a second electrode 82 provided on the second portion 64, and the semiconductor layer 60 having the second conductivity type is larger than the band gap of the material constituting the light emitting layer 30 and smaller than the band gap of the material constituting the GaN-based semiconductor layer 40.

[0031] Therefore, in the light emitting device 100, a current from the second electrode 82 flows in the in-plane direction through the semiconductor layer 60, reaches the GaN-based semiconductor layer 40, and is injected into the light emitting layer 30. The resistivity of the semiconductor layer 60 is lower than the resistivity of the GaN-based semiconductor layer 40. This makes it easier for a current to be injected into the center of the light emitting layer 30 compared to a case where a semiconductor layer such as a SiC layer is not provided. Therefore, in the light emitting device 100, a current can be injected into the light emitting layer 30 with good uniformity. Therefore, light can be generated in the light emitting layer 30 with good uniformity.

[0032] Furthermore, the difference between the band gap of the material constituting the light emitting layer 30 and the band gap of the semiconductor layer 60 may be larger than the difference between the band gap of the semiconductor layer 60 and the band gap of the material constituting the GaN-based semiconductor layer 40. This can reduce the energy barrier between the semiconductor layer 60 and the GaN-based semiconductor layer 40, and can reduce the contact resistance between the semiconductor layer 60 and the GaN-based semiconductor layer 40.

[0033] In the light emitting device 100, the semiconductor layer 60 having the second conductivity type is made of 4H-SiC, and the GaN-based semiconductor layer 40 is a GaN layer. The lattice constant of 4H-SiC is close to that of GaN. Therefore, in the light emitting device 100, the semiconductor layer 60 is easily lattice matched to the GaN-based semiconductor layer 40, and has few crystal defects. This can reduce the absorption loss of light generated in the light emitting layer 30 by the semiconductor layer 60.

[0034] In the light emitting device 100, the second multilayer mirror 70 is made up of a plurality of dielectric layers 72. Therefore, in the light emitting device 100, the refractive index difference between the high refractive index layer and the low refractive index layer constituting the DBR can be made larger and the reflection band can be made wider than in the case where the second multilayer mirror is made up of a plurality of GaN-based semiconductor layers, for example.

[0035] In the light emitting device 100, the first conductivity type is n-type and the second conductivity type is p-type. The p-type GaN-based semiconductor layer 40 has a higher resistivity than the n-type GaN-based semiconductor layer, but since the light emitting device 100 includes the semiconductor layer 60, a current can be injected into the light emitting layer 30 with good uniformity.

[0036] 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. Fig. 2 is a cross-sectional view that typically illustrates the manufacturing process of the light emitting device 100 according to this embodiment.

[0037] 2, a plurality of semiconductor layers 22 are formed on a substrate 10 to form a first multilayer mirror 20. The semiconductor layers 22 are formed by epitaxial growth using, for example, a metal organic chemical vapor deposition (MOCVD) method or a molecular beam epitaxy (MBE) method.

[0038] Next, the light emitting layer 30 is formed on the first multilayer mirror 20. The light emitting layer 30 is formed by epitaxial growth using, for example, the MOCVD method, the MBE method or the like.

[0039] Next, the GaN-based semiconductor layer 40 is formed on the light emitting layer 30. The GaN-based semiconductor layer 40 is formed by epitaxial growth using, for example, an MOCVD method, an MBE method, or the like.

[0040] Next, the insulating layer 50 is formed on the light emitting layer 30. The insulating layer 50 is formed by, for example, a chemical vapor deposition (CVD) method, a sputtering method, or the like.

[0041] Next, the insulating layer 50 is patterned to form the opening 52. The patterning is performed by, for example, photolithography and etching.

[0042] Next, the semiconductor layer 60 is formed on the GaN-based semiconductor layer 40 and the insulating layer 50. The semiconductor layer 60 is formed by epitaxial growth using, for example, an MOCVD method, an MBE method, or the like. The semiconductor layer 60 can be epitaxially grown also on the insulating layer 50 by lateral growth from the opening 52. By adjusting the growth temperature, for example, a semiconductor layer 60 having a high content of 4H—SiC, preferably a semiconductor layer 60 made of 4H—SiC, can be formed.

[0043] The semiconductor layer 60 may be formed by, for example, a sputtering method, a vacuum deposition method, etc., instead of epitaxial growth. However, in consideration of reducing crystal defects, the semiconductor layer 60 is preferably formed by epitaxial growth.

[0044] Next, a plurality of dielectric layers 72 are formed on the semiconductor layer 60 to form the second multilayer mirror 70. The dielectric layers 72 are formed by, for example, a CVD method, a sputtering method or the like.

[0045] 1, a first electrode 80 is formed under the substrate 10. Next, a second electrode 82 is formed on the semiconductor layer 60. The first electrode 80 and the second electrode 82 are formed by, for example, a vacuum deposition method or a sputtering method. The order in which the first electrode 80 and the second electrode 82 are formed is not particularly limited.

[0046] Through the above steps, the light emitting device 100 can be manufactured.

[0047] 3. Modifications of the Light Emitting Device 3.1. First variant Next, a light emitting device according to a first modified example of this embodiment will be described with reference to the drawings. Fig. 3 is a cross-sectional view showing a light emitting device 200 according to a first modified example of this embodiment. Hereinafter, in the light emitting device 200 according to the first modified example of this embodiment, members having the same functions as those of the light emitting device 100 according to this embodiment described above are given the same reference numerals, and detailed description thereof will be omitted.

[0048] The light emitting device 200 differs from the above-described light emitting device 100 in that the semiconductor layer 60 has a first layer 66 and a second layer 68, as shown in FIG.

[0049] The first layer 66 is provided on the GaN-based semiconductor layer 40 and on the insulating layer 50. The first layer 66 is provided between the GaN-based semiconductor layer 40 and the second multilayer mirror 70, and between the insulating layer 50 and the second layer 68. The first portion 62 of the semiconductor layer 60 is constituted by the first layer 66.

[0050] The second layer 68 is provided on the first layer 66. The second layer 68 is provided between the first layer 66 and the second electrode 82. The second portion 64 of the semiconductor layer 60 is composed of the first layer 66 and the second layer 68. The second layer 68 surrounds, for example, the second multilayer mirror 70 when viewed from the stacking direction.

[0051] The impurity concentration of the second layer 68 is higher than the impurity concentration of the first layer 66. The fact that the impurity concentration of the second layer 68 is higher than the impurity concentration of the first layer 66 can be confirmed by, for example, atom probe analysis.

[0052] In the light emitting device 200, the semiconductor layer 60 has a first layer 66 and a second layer 68 having a higher impurity concentration than the first layer 66, and the second layer 68 is provided between the first layer 66 and the second electrode 82. Therefore, in the light emitting device 200, the second layer 68 having a high impurity concentration can reduce the contact resistance between the semiconductor layer 60 and the second electrode 82. Furthermore, the first layer 66 having a low impurity concentration can reduce the absorption loss of light generated in the light emitting layer 30 by the semiconductor layer 60.

[0053] 3.2. Second variant Next, a light emitting device according to a second modified example of this embodiment will be described with reference to the drawings. Fig. 4 is a cross-sectional view showing a light emitting device 300 according to the second modified example of this embodiment. Hereinafter, in the light emitting device 300 according to the second modified example of this embodiment, the same reference numerals are used for components having the same functions as the components of the light emitting device 100 according to this embodiment and the light emitting device 200 according to the first modified example of this embodiment, and detailed description thereof will be omitted.

[0054] 4, the light emitting device 300 differs from the above-described light emitting device 100 in that it has a submount 90. In the illustrated example, the semiconductor layer 60 of the light emitting device 300 has a first layer 66 and a second layer 68, like the semiconductor layer 60 of the above-described light emitting device 200.

[0055] The submount 90 is provided on a support substrate 92. The material of the submount 90 is, for example, SiC. The support substrate 92 is, for example, a Si substrate. A terminal 94 is provided on the submount 90. The terminal 94 is provided on the side of the submount 90 opposite to the support substrate 92. The material of the terminal 94 is, for example, a metal.

[0056] The substrate 10, the first multilayer mirror 20, the light emitting layer 30, the GaN-based semiconductor layer 40, the insulating layer 50, the semiconductor layer 60, the second multilayer mirror 70, and the electrodes 80, 82 constitute a light emitting element 102. The light emitting element 102 is junction-down mounted on a submount 90. The second multilayer mirror 70 is provided between the submount 90 and the semiconductor layer 60.

[0057] An opening 81 is formed in the first electrode 80. The light emitting device 300 emits laser light from the opening 81. The second electrode 82 is connected to a terminal 94 via a bonding member 96. The bonding member 96 is, for example, solder or silver paste.

[0058] The light emitting device 300 includes a substrate 10 and a submount 90, with the first multilayer mirror 20 provided between the substrate 10 and the light emitting layer 30, and the second multilayer mirror 70 provided between the submount 90 and the semiconductor layer 60. Therefore, in the light emitting device 300, heat generated in the light emitting layer 30 can be dissipated via the submount 90.

[0059] 4. Three-dimensional printing equipment Next, a three-dimensional modeling apparatus according to this embodiment will be described with reference to the drawings. Fig. 5 is a diagram showing a three-dimensional modeling apparatus 400 according to this embodiment.

[0060] 5, the three-dimensional modeling apparatus 400 includes, for example, a light source 410, a galvano scanner 420, a lens 430, and a stage 440. The three-dimensional modeling apparatus 400 is a powder head type 3D printer.

[0061] A plurality of light sources 410 are provided. The plurality of light sources 410 are lined up in a predetermined direction. The plurality of light sources 410 emit laser light. Here, FIG. 6 is a diagram showing a schematic diagram of the light source 410.

[0062] As shown in FIG. 6, the light source 410 has, for example, a light emitting device 100, a lens 412, and a slit plate 414. A plurality of light emitting devices 100 are provided. The plurality of light emitting devices 100 are arranged in a predetermined direction. A plurality of lenses 412 are provided corresponding to the light emitting devices 100. The lenses 412 focus the light emitted from the light emitting devices 100. The slit plate 414 has a plurality of slits 416 formed corresponding to the light emitting devices 100. The slits 416 extract more parallel components from the light emitted from the lens 412. Although not shown, the light source 410 may have a uniform illumination system that enhances the uniformity of the intensity of the light emitted from the plurality of light emitting devices 100.

[0063] 5, the galvano scanner 420 reflects the light emitted from the light source 410. The light reflected by the galvano scanner 420 is irradiated onto the metal powder P on the stage 440 via the lens 430. The galvano scanner 420 can control the traveling direction of the light. Therefore, the light reflected by the galvano scanner 420 can irradiate the metal powder P with pinpoint accuracy.

[0064] The lens 430 condenses the light reflected by the galvano scanner 420. The light emitted from the lens 430 irradiates the metal powder P. The portion of the metal powder P irradiated with the light is sintered.

[0065] The stage 440 supports metal powder P. After the metal powder P is irradiated and sintered, the stage 440 moves in a direction away from the lens 430, as indicated by arrow A. Then, new metal powder is supplied onto the sintered metal powder P, and the new metal powder is irradiated with light emitted from the light source 410. By repeating this process of moving the stage 440, supplying the metal powder, and irradiating the metal powder with light a predetermined number of times, a three-dimensional object having a predetermined shape is formed.

[0066] 5. Modifications of the 3D printing device Next, a three-dimensional printing apparatus according to a modified example of this embodiment will be described with reference to the drawings. Fig. 7 is a schematic diagram of a three-dimensional printing apparatus 500 according to a modified example of this embodiment. Hereinafter, in the three-dimensional printing apparatus 500 according to the modified example of this embodiment, components having the same functions as those of the three-dimensional printing apparatus 400 according to the above-described embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted.

[0067] The above-mentioned three-dimensional modeling apparatus 400 is a powder head type 3D printer, as shown in FIG.

[0068] In contrast, the three-dimensional modeling apparatus 500 is a stereolithography type 3D printer using ultraviolet curing resin, as shown in FIG.

[0069] The three-dimensional modeling apparatus 500 includes, for example, a light source 410, a DLP (Digital Light Processing) 510, a container 520, and a stage 530.

[0070] Light emitted from the multiple light sources 410 is incident on the DLP 510. The DLP 510 receives the light emitted from the multiple light sources 410 and emits light from a predetermined pixel. The light emitted from the DLP 510 irradiates the resin material R in the container 520. The resin material R is an ultraviolet curable resin. The portion of the resin material R irradiated with the light is cured.

[0071] The cured portion of the resin material R adheres to the stage 530. After the cured portion adheres to the stage 530, the stage 530 moves in a direction away from the container 520, as indicated by arrow B. This irradiation of the resin material R with light and movement of the stage 530 are repeated a predetermined number of times, thereby forming a three-dimensional object M having a predetermined shape.

[0072] The resin material R may contain ceramic. This allows a three-dimensional object M made of ceramic to be formed. Also, an LCD (Liquid Crystal Display) may be used instead of the DLP 510.

[0073] 6. Head-mounted displays Next, a head mounted display (HMD) according to this embodiment will be described with reference to the drawings. Fig. 8 is a perspective view showing a schematic view of an HMD 600 according to this embodiment.

[0074] The HMD 600 is a head-mounted image display device as shown in Fig. 8. The HMD 600 has, for example, a right-eye image light generating unit 610a, a right-eye deflection member 612a that deflects the image light emitted from the right-eye image light generating unit 610a and makes it incident on the right eye Ea of the observer, a left-eye image light generating unit 610b, and a left-eye deflection member 612b that deflects the image light emitted from the left-eye image light generating unit 610b and makes it incident on the left eye Eb of the observer.

[0075] The HMD 600 has, for example, a shape similar to glasses. The HMD 600 has a frame 620. The frame 620 is worn on the head of the observer. The frame 620 has, for example, a front portion 622, a right temple 624a, and a left temple 624b. The front portion 622 supports a right eye deflection member 612a and a left eye deflection member 612b. The right temple 624a supports a right eye image light generation unit 610a. The left temple 624b supports a left eye image light generation unit 610b.

[0076] 9 is a diagram for explaining the optical system of the HMD 600. The configurations of the right-eye image light generating unit 610a and the left-eye image light generating unit 610b are basically the same. Therefore, in the following, only the configuration of the left-eye image light generating unit 610b will be described, and a description of the right-eye image light generating unit 610a will be omitted.

[0077] 9, the HMD 600 has a projection system optical unit 630, a correction system optical unit 632, and a diffraction element 634. For example, the projection system optical unit 630, the correction system optical unit 632, and the diffraction element 634 are arranged in this order along the traveling direction of the image light emitted from the left-eye image light generation unit 610b. The projection system optical unit 630, the correction system optical unit 632, and the diffraction element 634 configure a light guide device 602 that forms an optical path of the image light.

[0078] The left-eye image light generating unit 610b generates image light. The left-eye image light generating unit 610b has, for example, a light emitting device 100 and a liquid crystal display element (not shown). A plurality of light emitting devices 100 are provided. The liquid crystal display element receives light emitted from the light emitting device 100 and emits image light. Since the light emitting device 100 emits laser light with a narrow wavelength line width, the HMD 600 does not require a wavelength compensation element that compensates for the wavelength. Therefore, the weight and cost of the HMD 600 can be reduced. The image light generated by the left-eye image light generating unit 610b is incident on the projection system optical unit 630.

[0079] The projection system optical unit 630 is composed of optical elements such as lenses and mirrors. The projection system optical unit 630 has a function of controlling the radiation angle of the image light. Specifically, the projection system optical unit 630 adjusts the image light generated by the left eye image light generating unit 610b to a parallel light beam having an angle according to the position where the image light was generated. This allows the image light generated by the left eye image light generating unit 610b to be efficiently guided to the correction system optical unit 632.

[0080] The correction system optical unit 632 is composed of optical elements such as lenses and mirrors. The correction system optical unit 632 has a function of correcting aberrations such as distortion of the image light. This makes it possible to efficiently guide the image light whose aberrations have been corrected to the diffraction element 634.

[0081] The diffraction element 634 is provided on the left-eye deflection member 612b. The diffraction element 634 is, for example, configured by a reflective volume holographic element. The reflective volume holographic element is a partially reflective diffractive optical element, and the left-eye deflection member 612b is a partially transmissive and reflective combiner. Therefore, external light also enters the eye E through the left-eye deflection member 612b. This allows the observer to recognize an image in which the image light formed by the left-eye image light generation unit 610b and the external light are superimposed.

[0082] An incident surface 636 of the diffraction element 634 faces the viewer and is a concave curved surface that is concave in a direction away from the eye E. In other words, the incident surface 636 has a curved shape in which the center is concave with respect to the periphery in the incident direction of the image light. Therefore, the image light can be efficiently focused toward the viewer's eye E. Then, the image light reaches the retina E2 through the pupil E1 of the eye E, allowing the viewer to recognize the image.

[0083] The light emitting device according to the embodiment described above can be used for purposes other than the three-dimensional modeling device and the HMD. The light emitting device according to the embodiment described above can be used as a light source for, for example, projectors, indoor and outdoor lighting, laser printers, scanners, car lights, sensing devices such as pulse measuring devices that use light, communication devices, and the like.

[0084] 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 appropriately combined.

[0085] The present invention includes configurations that are substantially the same as the configurations described in the embodiments, for example, configurations with the same functions, methods, and results, or configurations with the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that achieve the same effects as the configurations described in the embodiments, or configurations that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

[0086] The following can be derived from the above-described embodiment and modifications.

[0087] One aspect of the light emitting device is a first multilayer mirror including a plurality of semiconductor layers having a first conductivity type; A second multilayer mirror; and a light emitting layer provided between the first multilayer mirror and the second multilayer mirror; a GaN-based semiconductor layer having a second conductivity type different from the first conductivity type, the GaN-based semiconductor layer being provided between the light emitting layer and the second multilayer mirror; a semiconductor layer having the second conductivity type, the semiconductor layer including a first portion provided between the GaN-based semiconductor layer and the second multilayer mirror, and a second portion not overlapping with the second multilayer mirror as viewed in a stacking direction of the first multilayer mirror and the light emitting layer; An electrode provided in the second portion; having The material constituting the semiconductor layer having the second conductivity type has a band gap larger than that of the material constituting the light emitting layer and smaller than that of the material constituting the GaN-based semiconductor layer.

[0088] According to this light emitting device, a current can be injected into the light emitting layer with good uniformity.

[0089] In one embodiment of the light emitting device, the semiconductor layer having the second conductivity type is made of 4H—SiC, The GaN-based semiconductor layer may be a GaN layer.

[0090] According to this light emitting device, it is possible to reduce the absorption loss of light generated in the light emitting layer by the SiC layer.

[0091] In one embodiment of the light emitting device, The semiconductor layer having the second conductivity type is The first layer, a second layer having a higher impurity concentration than the first layer; having The second layer may be provided between the first layer and the electrode.

[0092] In this light-emitting device, the second layer having a high impurity concentration can reduce the contact resistance between the electrode and the semiconductor layer having the second conductivity type, and the first layer having a low impurity concentration can reduce the absorption loss of light generated in the light-emitting layer by the semiconductor layer having the second conductivity type.

[0093] In one embodiment of the light emitting device, A substrate and a submount are provided. the first multilayer mirror is provided between the substrate and the light emitting layer, The second multilayer mirror may be provided between the submount and the semiconductor layer having the second conductivity type.

[0094] According to this light emitting device, the heat generated in the light emitting layer can be dissipated via the submount.

[0095] In one embodiment of the light emitting device, The second multilayer mirror may be made of a plurality of dielectric layers.

[0096] According to the light emitting device, the difference in refractive index between the high refractive index layer and the low refractive index layer constituting the DBR can be increased, and the reflection band can be widened.

[0097] In one embodiment of the light emitting device, the first conductivity type is n-type, The second conductivity type may be p-type.

[0098] In this light emitting device, the p-type GaN semiconductor layer has a higher resistivity than the p-type GaN semiconductor layer, but since the SiC layer is provided, a current can be injected into the light emitting layer with good uniformity.

[0099] One aspect of the three-dimensional printing apparatus includes: The present invention has one aspect of the light emitting device.

[0100] One embodiment of the head mounted display is The present invention has one aspect of the light emitting device. [Explanation of symbols]

[0101] 10...substrate, 20...first multilayer mirror, 22...semiconductor layer, 30...light emitting layer, 40...GaN-based semiconductor layer, 50...insulating layer, 60...semiconductor layer, 62...first portion, 64...second portion, 66...first layer, 68...second layer, 70...second multilayer mirror, 72...dielectric layer, 80...first electrode, 82...second electrode, 90...submount, 92...support substrate, 94...terminal, 96...bonding member, 100...light emitting device, 102...light emitting element, 200, 300...light emitting device, 400...three-dimensional modeling device, 410...light source, 412...lens, 414...slit plate, 4 16...slit, 420...galvano scanner, 430...lens, 440...stage, 500...three-dimensional modeling device, 510...DLP, 520...container, 530...stage, 600...HMD, 602...light guide device, 610a...right eye image light generation unit, 610b...left eye image light generation unit, 612a...right eye deflection member, 612b...left eye deflection member, 620...frame, 622...front portion, 624a...right temple, 624b...left temple, 630...projection system optical unit, 632...correction system optical unit, 634...diffraction element, 636...incident surface

Claims

1. a first multilayer mirror made up of a plurality of semiconductor layers having a first conductivity type; a second multilayer mirror; and a light-emitting layer provided between the first multilayer mirror and the second multilayer mirror; a GaN-based semiconductor layer having a second conductivity type different from the first conductivity type, the GaN-based semiconductor layer being provided between the light-emitting layer and the second multilayer mirror; a semiconductor layer having the second conductivity type, the semiconductor layer including a first portion provided between the GaN-based semiconductor layer and the second multilayer mirror and a second portion not overlapping with the second multilayer mirror when viewed from a stacking direction of the first multilayer mirror and the light emitting layer; an electrode provided on the second portion; and a band gap of a material constituting the semiconductor layer having the second conductivity type is larger than a band gap of a material constituting the light emitting layer and smaller than a band gap of a material constituting the GaN-based semiconductor layer;

2. In claim 1, the semiconductor layer having the second conductivity type is made of 4H—SiC, The light-emitting device, wherein the GaN-based semiconductor layer is a GaN layer.

3. In claim 1, The semiconductor layer having the second conductivity type is The first layer, a second layer having a higher impurity concentration than the first layer; and The second layer is provided between the first layer and the electrode.

4. In claim 1, a substrate and a submount, the first multilayer mirror is provided between the substrate and the light-emitting layer, The light-emitting device, wherein the second multilayer mirror is provided between the submount and the semiconductor layer having the second conductivity type.

5. In claim 1, The second multilayer mirror is made of a plurality of dielectric layers.

6. In claim 1, the first conductivity type is n-type, The light emitting device, wherein the second conductivity type is p-type.

7. A three-dimensional modeling apparatus comprising the light emitting device according to claim 1 .

8. A head-mounted display comprising the light-emitting device according to any one of claims 1 to 6.

Images