Lighting devices and projectors

Abstract

The present invention provides a light-emitting device and a projector. The light-emitting device can reduce the amount of reduction in light-emitting intensity near the outer edge of an electrode. The light-emitting device has n columnar portions and an electrode for injecting current into the n columnar portions, each of the n columnar portions has a first semiconductor layer, a second semiconductor layer of a conductivity type different from that of the first semiconductor layer, and a light-emitting layer arranged between the first semiconductor layer and the second semiconductor layer, and when observed from the stacking direction of the first semiconductor layer and the light-emitting layer, p first columnar portions among the n columnar portions do not overlap with the outer edge of the electrode, q second columnar portions among the n columnar portions overlap with the outer edge of the electrode, and the number of second columnar portions whose centers overlap with the electrode among the q second columnar portions is greater than the number of second columnar portions whose centers do not overlap with the electrode. Wherein, n=p+q.

Description

Technical Field

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

[0002] Semiconductor lasers are expected to be the next generation of high-brightness light sources. Among them, semiconductor lasers using nanorods are expected to be able to emit high-power light at a narrow radiation angle due to the photonic crystal effect of the nanorods.

[0003] For example, Patent Document 1 describes a semiconductor light emitting element having a plurality of nanocolumns formed by sequentially stacking an n-type GaN layer, a light emitting layer, and a p-type GaN layer. In such a light emitting element, the nanocolumns are grown in a two-dimensional array and electrodes are formed on the nanocolumns.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2007-27298

[0005] In the above-mentioned light-emitting element, especially when the nanopillars are densely arranged, there are nanopillars that overlap only a portion of the electrode at the outer edge of the electrode. If there are nanopillars that overlap only a portion of the electrode at the outer edge of the electrode, the light emission intensity may be lower near the outer edge of the electrode compared to the center of the electrode. Summary of the invention

[0006] One embodiment of the present invention is a light-emitting device, which has n columnar portions and an electrode for injecting current into the n columnar portions, wherein each of the n columnar portions has: a first semiconductor layer; a second semiconductor layer, the conductivity type of the second semiconductor layer is different from that of the first semiconductor layer; and a light-emitting layer, which is arranged between the first semiconductor layer and the second semiconductor layer, and when observed from the stacking direction of the first semiconductor layer and the light-emitting layer, p first columnar portions among the n columnar portions do not overlap with the outer edge of the electrode, q second columnar portions among the n columnar portions overlap with the outer edge of the electrode, and the number of second columnar portions whose centers overlap with the electrode among the q second columnar portions is greater than the number of second columnar portions whose centers do not overlap with the electrode. Wherein, n=p+q.

[0007] One embodiment of the present invention is a projector including the above-mentioned light emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a plan view schematically showing the light emitting device according to the first embodiment.

[0009] Figure 2 It is a cross-sectional view schematically showing the light emitting device according to the first embodiment.

[0010] Figure 3It is a cross-sectional view schematically showing the light emitting device according to the first embodiment.

[0011] Figure 4 It is a cross-sectional view schematically showing the manufacturing process of the light emitting device according to the first embodiment.

[0012] Figure 5 It is a cross-sectional view schematically showing a light emitting device according to a first modification example of the first embodiment.

[0013] Figure 6 It is a cross-sectional view schematically showing a light emitting device according to a first modification example of the first embodiment.

[0014] Figure 7 It is a top view schematically showing a light emitting device according to a second modification example of the first embodiment.

[0015] Figure 8 It is a cross-sectional view schematically showing a light emitting device according to a second modification example of the first embodiment.

[0016] Fig. 9 It is a cross-sectional view schematically showing a light emitting device according to a second modification example of the first embodiment.

[0017] Fig.10 It is a plan view schematically showing a light emitting device according to a second embodiment.

[0018] Fig.11 It is a cross-sectional view schematically showing a light emitting device according to a second embodiment.

[0019] Fig.12 It is a cross-sectional view schematically showing a light emitting device according to a second embodiment.

[0020] Fig.13 It is a cross-sectional view schematically showing a light emitting device according to a modified example of the second embodiment.

[0021] Fig.14 It is a cross-sectional view schematically showing a light emitting device according to a modified example of the second embodiment.

[0022] Fig.15 It is a plan view schematically showing a light emitting device according to a third embodiment.

[0023] Fig.16 It is a top view schematically showing the light emitting device according to the fourth embodiment.

[0024] Fig.17 It is a plan view schematically showing a light emitting module according to a fifth embodiment.

[0025] Fig.18 This is a diagram schematically showing a projector according to the sixth embodiment.

[0026] Description of symbols

[0027] 2: pixel; 4: facet; 5: c-plane; 6: outer edge; 6a: first side; 6b: second side; 6c: third side; 6d: fourth side; 10: substrate; 20: laminate; 22: buffer layer; 24: mask layer; 30: columnar portion; 30a, 30a1, 30a2: first columnar portion; 30b: second columnar portion; 32: first semiconductor layer; 34: light-emitting layer; 36: second semiconductor layer; 40: first electrode; 42: second electrode; 42a: first portion; 42b: second portion; 60: wiring; 70, 70a, 70b: pseudo columnar portion; 80: light propagation layer; 100: light-emitting device; 100R: red light source; 100G: green light source; 100B: blue light source; 110, 120, 200, 210, 300, 400: light-emitting device; 500: light-emitting module; 900: projector; 902R: first optical element; 902G: second optical element; 902B: third optical element; 904R: first light modulator; 904G: second light modulator; 904B: third light modulator; 906: cross-dichroic prism; 908: projection device; 910: screen. DETAILED DESCRIPTION

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail using the accompanying drawings. In addition, the embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, the structures described below are not necessarily all necessary components of the present invention.

[0029] 1. First Implementation Method

[0030] 1.1. Light-emitting device

[0031] 1.1.1. Overall structure

[0032] First, a light emitting device according to a first embodiment will be described with reference to the drawings. Figure 1 It is a plan view schematically showing the light emitting device 100 according to the first embodiment. Figure 2 The light emitting device 100 according to the first embodiment is schematically shown. Figure 1 Sectional view along line II-II. Figure 3 The light emitting device 100 according to the first embodiment is schematically shown. Figure 1 Cross-sectional view along line III-III.

[0033] like Figures 1 to 3As shown, the light emitting device 100 includes, for example, a substrate 10, a laminate 20, a first electrode 40, a second electrode 42, an insulating layer 50, a wiring 60, and a dummy columnar portion 70. The light emitting device 100 is, for example, a semiconductor laser. Figure 1 , the components other than the columnar portion 30, the second electrode 42, the wiring 60, and the dummy columnar portion 70 are omitted. Figure 1 In FIG. 1 , the second electrode 42 is shown in a transparent manner. The dummy columnar portion 70 corresponds to the third columnar portion in the claims.

[0034] The substrate 10 is, for example, a Si substrate, a GaN substrate, a sapphire substrate, a SiC substrate, or the like.

[0035] The laminated body 20 is provided on the substrate 10. In the example shown in the figure, the laminated body 20 is provided on the substrate 10. The laminated body 20 has a buffer layer 22 and a columnar portion 30, for example.

[0036] In this specification, in the stacking direction of the stacked body 20 (hereinafter, also 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 referred to as "upward", and the direction from the light emitting layer 34 toward the first semiconductor layer 32 is referred to as "downward". In addition, the direction perpendicular to the stacking direction is also referred to as the "in-plane direction". In addition, 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 of the columnar portion 30.

[0037] The buffer layer 22 is provided on the substrate 10. The buffer layer 22 is, for example, an n-type GaN layer doped with Si. A mask layer 24 for forming the columnar portion 30 is provided on the buffer layer 22. The mask layer 24 is, for example, a silicon oxide layer, a titanium layer, a titanium oxide layer, an aluminum oxide layer, or the like.

[0038] The columnar portion 30 is disposed on the buffer layer 22. The columnar portion 30 has a columnar shape protruding upward from the buffer layer 22. In other words, the columnar portion 30 protrudes upward from the substrate 10 via the buffer layer 22. The columnar portion 30 is also called a nanocolumn, a nanowire, a nanorod, or a nanopillar. The planar shape of the columnar portion 30 is, for example, a polygon or a circle. Figure 1 In the example shown, the planar shape of the columnar portion 30, that is, the shape of the outer edge of the columnar portion 30 viewed from the stacking direction, is a regular hexagon. However, the planar shape of the columnar portion 30 is not limited thereto. The planar shape of the columnar portion 30 may be, for example, a circle, an ellipse, or a polygon such as a hexagon.

[0039] The diameter of the columnar portion 30 is, for example, not less than 50 nm and not more than 500 nm. By setting the diameter of the columnar portion 30 to not more than 500 nm, a high-quality crystalline light-emitting layer 34 can be obtained, and the strain inside the light-emitting layer 34 can be reduced. As a result, the light generated in the light-emitting layer 34 can be amplified with higher efficiency.

[0040] In addition, the so-called "diameter of the columnar portion" is the diameter when the planar shape of the columnar portion 30 is a circle, and is the diameter of the smallest circle when the planar shape of the columnar portion 30 is a shape other than a circle. For example, the diameter of the columnar portion 30 is the diameter of the smallest circle that includes the polygon when the planar shape of the columnar portion 30 is a polygon, and is the diameter of the smallest circle that includes the ellipse when the planar shape of the columnar portion 30 is an ellipse.

[0041] There are multiple columnar portions 30. There are gaps between adjacent columnar portions 30, for example. The interval between adjacent columnar portions 30 is, for example, greater than 1 nm and less than 500 nm. When observed from the stacking direction, the multiple columnar portions 30 are arranged at a specified interval in a specified direction. In the example shown in the figure, the multiple columnar portions 30 are, for example, arranged in a triangular lattice. In addition, the configuration of the multiple columnar portions 30 is not particularly limited, and can be arranged in a square lattice or a rectangular lattice or other quadrilateral lattice. The multiple columnar portions 30 can show the effect of a photonic crystal.

[0042] In addition, the "pitch between columnar portions" refers to the distance between the centers C of the columnar portions 30 adjacent to each other in a predetermined direction. The "center of the columnar portion" is the center of the circle when the planar shape of the columnar portion 30 is a circle, and is the center of the smallest circle when the planar shape of the columnar portion 30 is a shape other than a circle. For example, the center of the columnar portion 30 is the center of the smallest circle that includes the polygon when the planar shape of the columnar portion 30 is a polygon, and is the center of the smallest circle that includes the ellipse when the planar shape of the columnar portion 30 is an ellipse.

[0043] like Figure 2 As shown, the columnar portion 30 includes a first semiconductor layer 32 , a light emitting layer 34 , and a second semiconductor layer 36 .

[0044] 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, for example, an n-type GaN layer doped with Si.

[0045] The light emitting layer 34 is disposed on the first semiconductor layer 32. The light emitting layer 34 is disposed between the first semiconductor layer 32 and the second semiconductor layer 36. The light emitting layer 34 generates light by injecting current. 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: multiple quantum well) structure consisting of a well layer and a barrier layer.

[0046] The number of well layers and barrier layers constituting the light emitting layer 34 is not particularly limited. For example, only one well layer may be provided, in which case the light emitting layer 34 has an SQW (Single Quantum Well) structure.

[0047] The second semiconductor layer 36 is provided on the light emitting layer 34. The second semiconductor layer 36 is a layer of conductivity type different from that of the first semiconductor layer 32. The second semiconductor layer 36 is, for example, a p-type GaN layer doped with Mg. The first semiconductor layer 32 and the second semiconductor layer 36 are cladding layers having a function of confining light in the light emitting layer 34.

[0048] The columnar portion 30 has a first surface 38 on the substrate 10 side and a second surface 39 on the opposite side to the first surface 38. In the example shown in the figure, the second surface 39 is composed of facets 4. The first surface 38 is, for example, the lower surface of the columnar portion 30. The second surface 39 is, for example, the upper surface of the columnar portion 30.

[0049] Although not shown, an OCL (Optical Confinement Layer) may be provided between the first semiconductor layer 32 and the light emitting layer 34 . Also, an EBL (Electron Blocking Layer) may be provided between the light emitting layer 34 and the second semiconductor layer 36 .

[0050] In the light emitting device 100, a pin diode is formed by the p-type second semiconductor layer 36, the i-type light emitting layer 34 not doped with impurities, and the n-type first semiconductor layer 32. In the light emitting device 100, when a forward bias voltage of the pin diode is applied between the first electrode 40 and the second electrode 42, a current is injected into the light emitting layer 34, and recombination of electrons and holes occurs in the light emitting layer 34. Light emission is generated by this recombination. The light generated by the light emitting layer 34 propagates in the in-plane direction, forms a standing wave by the photonic crystal effect generated by the plurality of columnar portions 30, and receives gain in the light emitting layer 34 to perform laser oscillation. Then, the light emitting device 100 emits the +1st order diffracted light and the -1st order diffracted light as laser light in the stacking direction.

[0051] In addition, 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 the light generated in the light-emitting layer 34, and the light-emitting device 100 can emit light only from the second electrode 42 side.

[0052] The first electrode 40 is provided on the buffer layer 22. The buffer layer 22 may also be in ohmic contact with the first electrode 40. The first electrode 40 is electrically connected to the first semiconductor layer 32. In the example shown in the figure, the first electrode 40 is electrically connected to the first semiconductor layer 32 via the buffer layer 22. The first electrode 40 is an electrode for injecting current into the light emitting layer 34. As the first electrode 40, for example, an electrode in which a Cr layer, a Ni layer, and an Au layer are stacked in this order from the buffer layer 22 side is used.

[0053] The second electrode 42 is provided on the second semiconductor layer 36. The second electrode 42 is electrically connected to the second semiconductor layer 36. The second semiconductor layer 36 may also be in ohmic contact with the second electrode 42. The second electrode 42 is another electrode for injecting current into the light emitting layer 34. As the second electrode 42, for example, ITO (indium tin oxide) or the like is used.

[0054] When viewed from the stacking direction, the insulating layer 50 is provided around the second electrode 42. The insulating layer 50 is provided on the dummy columnar portion 70. The insulating layer 50 is, for example, a silicon oxide layer. The insulating layer 50 electrically isolates the columnar portion 30 from the wiring 60.

[0055] The wiring 60 is provided on the second electrode 42 and the insulating layer 50 . The wiring 60 is, for example, a Cu layer, an Al layer, a layer composed of an alloy of Cu and Al, a Ti layer, a W layer, etc. The wiring 60 is a wiring for passing a current through the second electrode 42 .

[0056] The dummy columnar portion 70 is provided on the buffer layer 22. The shape and size of the dummy columnar portion 70 are, for example, the same as those of the columnar portion 30. The material of the dummy columnar portion 70 is the same as that of the columnar portion 30. When viewed from the stacking direction, the dummy columnar portion 70 does not overlap with the second electrode 42. The dummy columnar portion 70 does not contact the second electrode 42.

[0057] In the above description, the InGaN-based light emitting layer 34 is described, but various materials that can emit light by injecting current can be used as the light emitting layer 34, depending on the wavelength of the emitted light. For example, semiconductor materials such as AlGaN-based, AlGaAs-based, InGaAs-based, InGaAsP-based, InP-based, GaP-based, and AlGaP-based can be used.

[0058] In addition, the light emitting device 100 is not limited to a laser, and may be an LED (Light Emitting Diode).

[0059] 1.1.2. Relationship between columnar portion and second electrode

[0060] The light emitting device 100 includes a pixel 2. The pixel 2 includes n columnar portions 30 and a second electrode 42 for injecting current into each of the n columnar portions 30. The pixel 2 includes, for example, a buffer layer 22 and a first electrode 40. n is, for example, an integer greater than 20. Figure 1 In the example shown, n = 72. When viewed from the stacking direction, each of the n columnar portions 30 overlaps with the second electrode 42. The n columnar portions 30 are arranged in a triangular lattice.

[0061] When viewed from the stacking direction, the p first columnar portions 30a among the n columnar portions 30 do not overlap with the outer edge 6 of the second electrode 42. p is an integer greater than zero. Figure 1 In the example shown, p = 42. Figure 2 In the illustrated example, the first columnar portion 30 a is in contact with the second electrode 42 over the entire second surface 39 .

[0062] When viewed from the stacking direction, q second columnar portions 30b among the n columnar portions 30 overlap with the outer edge 6 of the second electrode 42. Here, n=p+q. q is an integer greater than zero. Figure 1 In the example shown, q = 30. Figure 2 In the illustrated example, the second columnar portion 30 b is in contact with the second electrode 42 at a portion of the second surface 39 .

[0063] When viewed from the stacking direction, the number of the second columnar portions 30b whose centers C overlap with the second electrode 42 among the q second columnar portions 30b is greater than the number of the second columnar portions 30b whose centers C do not overlap with the second electrode 42. Figure 1 In the example shown, the number of the second columnar portions 30b whose center C overlaps with the second electrode 42 among the q second columnar portions 30b is 21. The number of the second columnar portions 30b whose center C does not overlap with the second electrode 42 among the q second columnar portions 30b is 9. The position of the center C is, for example, the position of the vertex of the facet 4.

[0064] When viewed from the stacking direction, the outer edge 6 of the second electrode 42 has, for example, a first side 6 a , a second side 6 b , a third side 6 c , and a fourth side 6 d .

[0065] The first side 6a is parallel to the first line segment L connecting the centers of the adjacent columnar portions 30 among the n columnar portions 30. The second side 6b is parallel to the first side 6a. The third side 6c is perpendicular to the first side 6a. The fourth side 6d is parallel to the third side 6c. The planar shape of the second electrode 42 is, for example, a rectangle. The length of the first side 6a is an integer multiple of the spacing between the n columnar portions 30, and in the example shown in the figure, is 7 times the spacing between the n columnar portions 30. In addition, the planar shape of the second electrode 42 is not limited to a rectangle.

[0066] When viewed from the stacking direction, the center C of each of the r second columnar portions 30b overlapping the first side 6a among the q second columnar portions 30b overlaps with the second electrode 42. r is an integer greater than zero. In the illustrated example, r=7. The center C of each of the s second columnar portions 30b overlapping the second side 6b among the q second columnar portions 30b overlaps with the second electrode 42. s is an integer greater than zero. In the illustrated example, s=7.

[0067] When viewed from the stacking direction, the center C of each of the v second columnar portions 30b overlapping the third side 6c overlaps with the second electrode 42. v is an integer greater than zero. In the example shown in the figure, v=4. The center C of each of the w second columnar portions 30b overlapping the fourth side 6d overlaps with the second electrode 42. w is an integer greater than zero. In the example shown in the figure, w=5.

[0068] The light emitting device 100 has t dummy columnar portions 70. For example, t is an integer greater than or equal to 10. Figure 1 In the example shown, t=38. When viewed from the stacking direction, the dummy columnar portion 70 does not overlap with the second electrode 42 . The t dummy columnar portions 70 surround the n columnar portions 30 .

[0069] In the example shown in the figure, the first columnar portion 30a is not adjacent to the pseudo columnar portion 70 in the direction of the first side 6a. That is, in the example shown in the figure, there is no pseudo columnar portion 70 adjacent to the first columnar portion 30a in the direction of the first side 6a. Here, "the pseudo columnar portion 70 adjacent to the first columnar portion 30a in the direction of the first side 6a" refers to the pseudo columnar portion 70 in which the line segment parallel to the first side 6a connecting the center C of the first columnar portion 30a and the center of the pseudo columnar portion 70 does not intersect with the second columnar portion 30b. In addition, "the direction of the first side 6a" refers to the extending direction of the first side 6a.

[0070] 1.1.3. Effects

[0071] In the light-emitting device 100, when viewed from the stacking direction, p first columnar portions 30a among the n columnar portions 30 do not overlap with the outer edge 6 of the second electrode 42, q second columnar portions 30b among the n columnar portions 30 overlap with the outer edge 6 of the second electrode 42, and the number of second columnar portions 30b whose centers C overlap with the second electrode 42 among the q second columnar portions 30b is greater than the number of second columnar portions 30b whose centers C do not overlap with the second electrode 42, n=p+q. Therefore, in the light-emitting device 100, the number of second columnar portions 30b that do not emit light due to non-luminescent coupling caused by dangling bonds can be reduced, compared to a case where the number of second columnar portions 30b whose centers C overlap with the second electrode 42 is less than the number of second columnar portions 30b whose centers C do not overlap with the second electrode 42. As a result, the amount of reduction in light emission intensity near the outer edge of the second electrode 42 can be reduced. Dangling bonds exist on the side surfaces of the columnar portion, and even if current is injected only near the outer periphery of the upper surface of the columnar portion, the current becomes non-luminescent coupling, so that the columnar portion may not emit light.

[0072] In the light-emitting device 100, when viewed from the stacking direction, the n columnar portions 30 are arranged in a triangular lattice, the outer edge 6 of the second electrode 42 has a first side 6a parallel to a first line segment L connecting centers C of adjacent columnar portions 30 among the n columnar portions 30, and the center C of each of the r second columnar portions 30b overlapping the first side 6a among the q second columnar portions 30b overlaps the second electrode 42. Therefore, in the light-emitting device 100, the r second columnar portions 30b overlapping the first side 6a can be made to emit light more reliably.

[0073] In the light-emitting device 100, when viewed from the stacking direction, the outer edge 6 of the second electrode 42 has a second side 6b parallel to the first side 6a, and the center C of each of the s second columnar portions 30b overlapping the second side 6b among the q second columnar portions 30b overlaps with the second electrode 42. Therefore, in the light-emitting device 100, the s second columnar portions 30b overlapping the second side 6b can be made to emit light more reliably.

[0074] In the light-emitting device 100, when viewed from the stacking direction, there are t dummy columnar portions 70 that do not overlap with the second electrode 42, and the t dummy columnar portions 70 surround the n columnar portions 30. Therefore, in the light-emitting device 100, the t dummy columnar portions 70 can reduce damage to the n columnar portions 30 when manufacturing the light-emitting device 100. If damage is applied to the columnar portion, crystal defects will occur, which may cause current leakage.

[0075] 1.2. Method for manufacturing a light-emitting device

[0076] Next, a method for manufacturing the light emitting device according to the first embodiment will be described with reference to the drawings. Figure 4It is a cross-sectional view schematically showing the manufacturing process of the light emitting device 100 according to the first embodiment.

[0077] like Figure 4 As shown, the buffer layer 22 is epitaxially grown on the substrate 10. Examples of epitaxial growth methods include MOCVD (Metal Organic Chemical Vapor Deposition) and MBE (Molecular Beam Epitaxy).

[0078] Next, a mask layer 24 is formed on the buffer layer 22. The mask layer 24 is formed by film formation and patterning by, for example, electron beam deposition or sputtering. The patterning is performed by photolithography and etching.

[0079] like Figure 1 As shown, the first semiconductor layer 32, the light emitting layer 34, and the second semiconductor layer 36 are epitaxially grown in sequence on the buffer layer 22 using the mask layer 24 as a mask. As a method of epitaxial growth, for example, MOCVD method, MBE method, etc. can be cited. Through this process, a plurality of columnar portions 30 can be formed. In addition, through this process, a plurality of pseudo columnar portions 70 can be formed.

[0080] Next, the first electrode 40 is formed on the buffer layer 22, and the second electrode 42 is formed on the second semiconductor layer 36. The first electrode 40 and the second electrode 42 are formed by, for example, vacuum deposition, etc. The order of forming the first electrode 40 and the second electrode 42 is not particularly limited.

[0081] Through the above steps, the light emitting device 100 can be manufactured.

[0082] 1.3. Modifications of Light Emitting Device

[0083] 1.3.1. First variant

[0084] Next, a light emitting device according to a first modification example of the first embodiment will be described with reference to the drawings. Figure 5 and Figure 6 : is a cross-sectional view schematically showing a light emitting device 110 according to a first modification of the first embodiment. Figure 5 Corresponding to the II-II line cross-sectional view of the above-mentioned light emitting device 100, Figure 6 This corresponds to a cross-sectional view taken along line III-III of the light emitting device 100 .

[0085] Hereinafter, in the light emitting device 110 of the first variant of the first embodiment, the same reference numerals are given to components having the same functions as the components of the light emitting device 100 of the first embodiment described above, and their detailed descriptions are omitted. This is also the same for the light emitting device of the second variant of the first embodiment described below.

[0086] In the above-mentioned light emitting device 100, Figure 2 and Figure 3 As shown, there is a gap between adjacent columnar portions 30 .

[0087] In contrast, in the light emitting device 110, as Figure 5 and Figure 6 As shown, a light propagation layer 80 is provided between adjacent columnar portions 30. In the example shown in the figure, the light propagation layer 80 is provided on the mask layer 24. The light propagation layer 80 is, for example, a silicon oxide layer. In the light emitting device 110, light generated by the light emitting layer 34 is transmitted in the in-plane direction through the light propagation layer 80. The light propagation layer 80 is formed, for example, by a CVD (Chemical Vapor Deposition) method or a spin coating method.

[0088] 1.3.2. Second variant

[0089] Next, a light emitting device according to a second modification of the first embodiment will be described with reference to the drawings. Figure 7 It is a plan view schematically showing a light emitting device 120 according to a second modification example of the first embodiment. Figure 8 1 is a cross-sectional view taken along line VIII-VIII schematically showing a light emitting device 120 according to a second modification of the first embodiment. Fig. 9 FIG. 1 is a schematic cross-sectional view of the light emitting device 120 according to the second modified example of the first embodiment, taken along line IX-IX. Figure 7 , the components other than the columnar portion 30, the second electrode 42, the wiring 60, and the dummy columnar portion 70 are omitted. Figure 7 In FIG. 1 , the second electrode 42 is shown transparently.

[0090] In the above-mentioned light emitting device 100, Figure 2 and Figure 3 As shown in FIG. 1 , an insulating layer 50 is provided around the second electrode 42 when viewed from the stacking direction.

[0091] In contrast, in the light emitting device 120, as Figure 7 to Figure 9 As shown, the insulating layer 50 is not provided. In the light emitting device 120, the wiring 60 is wire bonding.

[0092] In the light emitting device 120 , since the insulating layer 50 is not provided, the manufacturing process can be simplified.

[0093] 2. Second Implementation Method

[0094] 2.1. Light-emitting device

[0095] Next, a light emitting device according to a second embodiment will be described with reference to the drawings. Fig.10 It is a plan view schematically showing a light emitting device 200 according to the second embodiment. Fig.11 The light emitting device 200 according to the second embodiment is schematically shown. Fig.10 XI-XI line cross-sectional view. Fig.12 The light emitting device 200 according to the second embodiment is schematically shown. Fig.10 In addition, for convenience, Fig.10 , the components other than the columnar portion 30, the second electrode 42, the wiring 60, and the dummy columnar portion 70 are omitted. Fig.10 In FIG. 1 , the second electrode 42 is shown transparently.

[0096] Hereinafter, in the light emitting device 200 of the second embodiment, components having the same functions as those of the components of the light emitting device 100 of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0097] In the light emitting device 200, as Figure 10 to Figure 12 As shown, the second electrode 42 is different from the above-mentioned light-emitting device 100 in that it has a first portion 42 a and a second portion 42 b .

[0098] like Fig.11 and Fig.12 As shown, the first portion 42a is provided on the second semiconductor layer 36. The material of the first portion 42a is, for example, Au or Pt. The resistance of the first portion 42a is, for example, lower than the resistance of the second portion 42b. The second portion 42b is provided on the first portion 42a. The material of the second portion 42b is, for example, ITO.

[0099] In the light emitting device 200, for example, the second electrode 42 contacts the second semiconductor layer 36 at the first portion 42a made of Au or Pt. Therefore, the contact resistance between the second semiconductor layer 36 and the second electrode 42 can be reduced compared to the case where the second electrode is made of only ITO.

[0100] 2.2. Modifications of Light Emitting Device

[0101] Next, a light emitting device according to a modified example of the second embodiment will be described with reference to the drawings. Fig.13 as well as Fig.14 2 is a cross-sectional view schematically showing a light emitting device 210 according to a modified example of the second embodiment. Fig.13 Corresponds to Fig.10 The XI-XI line cross-sectional view, Fig.14 Corresponds to Fig.10 Sectional view along line XII-XII.

[0102] In the above-mentioned light emitting device 200, as Fig.11 and Fig.12 As shown, the second surface 39 of the columnar portion 30 is composed of facets 4 .

[0103] In contrast, in the light emitting device 210, as Fig.13 and Fig.14 As shown, the second surface 39 of the columnar portion 30 is composed of the facet 4 and the c-plane 5. The c-plane 5 is a plane parallel to the upper surface of the substrate 10.

[0104] When viewed from the stacking direction, the c-plane 5 constitutes the center C of the second columnar portion 30b. Fig.13 In the example shown, the second columnar portion 30b whose center C among the q second columnar portions 30b does not contact the second electrode 42 does not contact the second electrode 42 at the c-plane 5, but contacts the second electrode 42 at the facet 4. However, the present invention is not limited thereto, and the second columnar portion 30b whose center C among the q second columnar portions 30b does not contact the second electrode 42 may contact the second electrode 42 at the c-plane 5 and the facet 4. Fig.14 In the example shown, the second columnar portion 30b in which the center C among the q second columnar portions 30b is in contact with the second electrode 42 is in contact with the second electrode 42 at the facet 4 and the c-plane 5. In addition, in the second columnar portion 30b in which the center C among the q second columnar portions 30b is in contact with the second electrode 42, the second electrode 42 may be in contact with only a portion of the c-plane 5. In the second columnar portion 30b in which the center C among the q second columnar portions 30b is in contact with the second electrode 42, the second electrode 42 may be in contact with a portion of the c-plane 5 and separated from the facet 4.

[0105] For example, when an InGaN layer is used as a well layer of the light-emitting layer 34, when viewed from the stacking direction, an InGaN layer having a high atomic concentration (at%) of In is formed at the center of the light-emitting layer 34, and an InGaN layer having a low atomic concentration of In is formed near the periphery. The light emission intensity of the InGaN layer having a low atomic concentration of In is small, and sometimes no light is emitted. Therefore, by making the number of second columnar portions 30b whose centers C overlap with the second electrode 42 larger than the number of second columnar portions 30b whose centers C do not overlap with the second electrode 42, the amount of reduction in light emission intensity near the outer edge of the second electrode 42 can be reduced. In addition, when the light-emitting layer 34 has a c-plane region and a facet region, in the second columnar portions 30b whose centers C do not contact the second electrode 42 among the q second columnar portions 30b, the second electrode 42 may overlap only the facet region of the light-emitting layer 34, and not overlap the c-plane region of the light-emitting layer 34, when viewed from the stacking direction. In addition, in the case where the light-emitting layer 34 has a c-plane region and a facet region, in the second columnar portion 30b in which the center C of q second columnar portions 30b does not contact the second electrode 42, the second electrode 42 may also overlap with the facet region of the light-emitting layer 34 and a portion of the c-plane region of the light-emitting layer 34 when observed from the stacking direction.

[0106] 3. Third Implementation Method

[0107] Next, a light emitting device according to a third embodiment will be described with reference to the drawings. Fig.15 FIG. 3 is a schematic top view showing a light emitting device 300 according to the third embodiment. Fig.15 , the components other than the columnar portion 30, the second electrode 42, the wiring 60, and the dummy columnar portion 70 are omitted. Fig.15 In FIG. 1 , the second electrode 42 is shown transparently.

[0108] Hereinafter, in the light emitting device 300 of the third embodiment, components having the same functions as those of the components of the light emitting device 100 of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0109] In the above-mentioned light emitting device 100, Figure 1 As shown, there is no dummy columnar portion 70 adjacent to the first columnar portion 30 a in the direction of the first side 6 a .

[0110] In contrast, in the light emitting device 300, as Fig.15 As shown, there exists a dummy columnar portion 70 adjacent to the first columnar portion 30a in the direction of the first side 6a. For example, the first columnar portion 30a1 is adjacent to the dummy columnar portion 70a. In addition, the first columnar portion 30a2 is adjacent to the dummy columnar portion 70b.

[0111] The third side 6c of the outer edge 6 of the second electrode 42 passes between the first columnar portion 30a1 and the pseudo columnar portion 70a adjacent in the direction of the first side 6a among the p first columnar portions 30a and the t pseudo columnar portions 70. The center C of each of the u second columnar portions 30b overlapping the third side 6c among the q second columnar portions 30b overlaps with the second electrode 42. u is an integer greater than zero. In the example shown in the figure, u=4. In the light-emitting device 300, the u second columnar portions 30b overlapping the third side 6c can be made to emit light more reliably.

[0112] The fourth side 6d of the outer edge 6 of the second electrode 42 passes between the first columnar portion 30a2 and the pseudo columnar portion 70b adjacent in the direction of the first side 6a among the p first columnar portions 30a and the t pseudo columnar portions 70. The center C of each of the x second columnar portions 30b overlapping the fourth side 6d among the q second columnar portions 30b overlaps with the second electrode 42. x is an integer greater than zero. In the example shown in the figure, x=4. In the light-emitting device 300, the x second columnar portions 30b overlapping the fourth side 6d can be made to emit light more reliably.

[0113] In the light emitting device 300, when viewed from the stacking direction, the center C of each of the q second columnar portions 30b overlaps with the second electrode 42. Therefore, in the light emitting device 300, the q second columnar portions 30b can be made to emit light more reliably.

[0114] 4. Fourth Implementation Method

[0115] Next, a light emitting device according to a fourth embodiment will be described with reference to the drawings. Fig.16 FIG. 4 is a schematic top view showing a light emitting device 400 according to the fourth embodiment. Fig.16 , the components other than the columnar portion 30, the second electrode 42, the wiring 60, and the dummy columnar portion 70 are omitted. Fig.16 In FIG. 1 , the second electrode 42 is shown transparently.

[0116] Hereinafter, in the light emitting device 400 of the fourth embodiment, components having the same functions as those of the components of the light emitting device 100 of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0117] In the above-mentioned light emitting device 100, Figure 1 As shown, the length of the first side 6 a is an integral multiple of the pitch of the n columnar portions 30 .

[0118] In contrast, in the light emitting device 400, as Fig.16As shown, the length of the first side 6a is not an integral multiple of the pitch of the n columnar portions 30. The center C of each of the w second columnar portions 30b overlapping the fourth side 6d overlaps the second electrode 42, and w=4.

[0119] 5. Fifth Implementation Method

[0120] Next, a light emitting module according to a fifth embodiment will be described with reference to the drawings. Fig.17 FIG. 5 is a schematic top view showing a light emitting module 500 according to the fifth embodiment. Fig.17 , the components other than the columnar portion 30, the second electrode 42, the wiring 60, and the dummy columnar portion 70 are omitted. Fig.17 In FIG. 1 , the second electrode 42 is shown transparently.

[0121] like Fig.17 As shown, the light emitting module 500 includes a plurality of light emitting devices 100. The plurality of light emitting devices 100 are arranged in a matrix in the direction of the first side 6a and the direction of the third side 6c. The number of the plurality of light emitting devices 100 is not particularly limited, and is 16 in the example shown in the figure. In the example shown in the figure, the second electrodes 42 of the plurality of light emitting devices 100 arranged in the direction of the first side 6a are electrically connected to each other through the wiring 60.

[0122] In the plurality of light emitting devices 100 constituting the light emitting module 500 , the substrates 10 are provided continuously and integrally with each other. This also applies to the buffer layer 22 and the mask layer 24 .

[0123] 6. Sixth Implementation Method

[0124] Next, a projector according to a sixth embodiment will be described with reference to the drawings. Fig.18 It is a diagram schematically showing a projector 900 according to the sixth embodiment.

[0125] The projector 900 includes, for example, a light emitting device 100 as a light source.

[0126] The projector 900 includes a housing (not shown) and a red light source 100R, a green light source 100G, and a blue light source 100B disposed in the housing and emitting red light, green light, and blue light, respectively. Fig.18 In FIG. 1 , the red light source 100R, the green light source 100G, and the blue light source 100B are simplified.

[0127] The projector 900 further includes a first optical element 902R, a second optical element 902G, a third optical element 902B, a first light modulator 904R, a second light modulator 904G, a third light modulator 904B, and a projection device 908, which are arranged in a housing. The first light modulator 904R, the second light modulator 904G, and the third light modulator 904B are, for example, transmissive liquid crystal light valves. The projection device 908 is, for example, a projection lens.

[0128] The light emitted from the red light source 100R enters the first optical element 902R. The light emitted from the red light source 100R is condensed by the first optical element 902R. The first optical element 902R may have functions other than condensing light. The same is true for the second optical element 902G and the third optical element 902B described later.

[0129] The light focused by the first optical element 902R enters the first light modulator 904R. The first light modulator 904R modulates the incident light according to image information. Then, the projection device 908 magnifies the image formed by the first light modulator 904R and projects it onto the screen 910.

[0130] The light emitted from the green light source 100G enters the second optical element 902G. The light emitted from the green light source 100G is condensed by the second optical element 902G.

[0131] The light focused by the second optical element 902G enters the second light modulator 904G. The second light modulator 904G modulates the incident light according to the image information. Then, the projection device 908 enlarges the image formed by the second light modulator 904G and projects it onto the screen 910.

[0132] The light emitted from the blue light source 100B enters the third optical element 902B. The light emitted from the blue light source 100B is condensed by the third optical element 902B.

[0133] The light focused by the third optical element 902B enters the third light modulator 904B. The third light modulator 904B modulates the incident light according to the image information. Then, the projection device 908 enlarges the image formed by the third light modulator 904B and projects it onto the screen 910.

[0134] Furthermore, the projector 900 can include a cross dichroic prism 906 that combines the light emitted from the first light modulator 904R, the second light modulator 904G, and the third light modulator 904B and guides the combined light to the projection device 908 .

[0135] The three color lights modulated by the first light modulator 904R, the second light modulator 904G, and the third light modulator 904B are incident on the cross dichroic prism 906. The cross dichroic prism 906 is formed by bonding four right-angle prisms, and a dielectric multilayer film reflecting red light and a dielectric multilayer film reflecting blue light are arranged on its inner surface. The three color lights are synthesized by these dielectric multilayer films to form light representing a color image. Then, the synthesized light is projected onto the screen 910 through the projection device 908 to display the enlarged image.

[0136] In addition, the red light source 100R, the green light source 100G, and the blue light source 100B may also directly form an image without using the first light modulator 904R, the second light modulator 904G, and the third light modulator 904B by controlling the light emitting device 100 as a pixel of the image according to the image information. Furthermore, the projection device 908 may also enlarge the image formed by the red light source 100R, the green light source 100G, and the blue light source 100B and project it onto the screen 910.

[0137] In the above example, a transmissive liquid crystal light valve is used as the light modulating device, but a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such light valves include reflective liquid crystal light valves and digital micro mirror devices. In addition, the structure of the projection device may be appropriately changed according to the type of light valve used.

[0138] Furthermore, the light source can also be applied to a light source device of a scanning type image display device having a scanning unit which is an image forming device that displays an image of a desired size on a display surface by scanning light from a light source on a screen.

[0139] The light-emitting device of the above embodiment can also be used in devices other than projectors. In applications other than projectors, there are, for example, indoor and outdoor lighting, display backlights, laser printers, scanners, vehicle-mounted lights, sensing devices using light, light sources for communication devices, and the like. In addition, the light-emitting device of the above embodiment can also be applied to light-emitting elements of LED displays that display images by arranging tiny light-emitting elements in an array. In addition, the light-emitting device of the above embodiment can also be applied to display devices of head-mounted displays or smart glasses. That is, an LED display to which the light-emitting device of the above embodiment is applied can be used as a display device of a head-mounted display or smart glasses.

[0140] The above-mentioned embodiment and modification examples are examples, and the present invention is not limited thereto. For example, each embodiment and each modification example may be appropriately combined.

[0141] The present invention includes structures that are substantially the same as the structures described in the embodiments, such as structures with the same functions, methods and results, or structures with the same purposes and effects. In addition, the present invention includes structures obtained by replacing non-essential parts of the structures described in the embodiments. In addition, the present invention includes structures that can play the same role and effect as the structures described in the embodiments, or structures that can achieve the same purpose. In addition, the present invention includes structures obtained by adding known technologies to the structures described in the embodiments.

[0142] The following contents are derived from the above-mentioned embodiment and modification examples.

[0143] One mode of a light-emitting device comprises n columnar portions and an electrode for injecting current into the n columnar portions, wherein each of the n columnar portions comprises: a first semiconductor layer; a second semiconductor layer having a conductivity type different from that of the first semiconductor layer; and a light-emitting layer disposed between the first semiconductor layer and the second semiconductor layer, wherein when observed from the stacking direction of the first semiconductor layer and the light-emitting layer, p first columnar portions among the n columnar portions do not overlap with an outer edge of the electrode, q second columnar portions among the n columnar portions overlap with an outer edge of the electrode, and the number of second columnar portions whose centers overlap with the electrode among the q second columnar portions is greater than the number of second columnar portions whose centers do not overlap with the electrode, wherein n=p+q.

[0144] According to this light emitting device, it is possible to reduce the amount of decrease in light emission intensity near the outer edge of the electrode.

[0145] In one aspect of the light emitting device, when viewed from the stacking direction, a center of each of the q second columnar portions may overlap with the electrode.

[0146] According to this light emitting device, the q second columnar portions can be made to emit light more reliably.

[0147] In one aspect of the light emitting device, each of the n columnar portions may have a facet.

[0148] In one embodiment of the light-emitting device, the n columnar portions may be arranged in a triangular lattice when observed from the stacking direction, the outer edge of the electrode has a first side parallel to a first line segment connecting the centers of adjacent columnar portions among the n columnar portions, and the centers of r second columnar portions among the q second columnar portions overlapping with the first side overlap with the electrode.

[0149] According to this light emitting device, the r second columnar portions can be made to emit light more reliably.

[0150] In one embodiment of the light-emitting device, when viewed from the stacking direction, the outer edge of the electrode may have a second side parallel to the first side, and the center of each of the s second columnar portions among the q second columnar portions overlapping the second side overlaps with the electrode.

[0151] According to this light emitting device, the s second columnar portions can be made to emit light more reliably.

[0152] In one aspect of the light emitting device, when viewed from the stacking direction, the light emitting device may include t third columnar portions that do not overlap with the electrode, and the t third columnar portions may surround the n columnar portions.

[0153] According to this light emitting device, the t third columnar portions can reduce damage to the n columnar portions when manufacturing the light emitting device.

[0154] In one embodiment of the light-emitting device, the outer edge of the electrode may have a third side perpendicular to the first side when observed from the stacking direction, the third side passes through between the first columnar portion and the third columnar portion adjacent to each other in the direction of the first side among the p first columnar portions and the t third columnar portions, and the centers of the u second columnar portions overlapping with the third side among the q second columnar portions overlap with the electrode.

[0155] According to this light emitting device, the u second columnar portions can emit light more reliably.

[0156] In one aspect of the light emitting device, when viewed from the stacking direction, an outer edge of each of the n columnar portions may be a hexagon.

[0157] One embodiment of a projector includes one embodiment of the above-mentioned light emitting device.

Claims

1. A light emitting device, wherein: The light emitting device comprises n columnar portions and electrodes for injecting current into the n columnar portions. Each of the n columnar portions has: A first semiconductor layer; a second semiconductor layer, the conductivity type of the second semiconductor layer being different from that of the first semiconductor layer; as well as a light emitting layer disposed between the first semiconductor layer and the second semiconductor layer, The second semiconductor layer is provided between the electrode and the light emitting layer. When viewed from the stacking direction of the first semiconductor layer and the light emitting layer, The p first columnar portions among the n columnar portions do not overlap with the outer edge of the electrode, The q second columnar portions among the n columnar portions overlap with the outer edge of the electrode, The number of the second columnar portions whose centers overlap with the electrode among the q second columnar portions is greater than the number of the second columnar portions whose centers do not overlap with the electrode. The electrode is electrically connected to the second semiconductor layer of the first columnar portion and the second semiconductor layer of the second columnar portion. The diameter of each of the n columnar portions is not less than 50 nm and not more than 500 nm, The interval between adjacent columnar portions among the n columnar portions is greater than or equal to 1 nm and less than or equal to 500 nm, Among them, n=p+q.

2. The light emitting device according to claim 1, wherein: When viewed from the stacking direction, the center of each of the q second columnar portions overlaps with the electrode.

3. The light emitting device according to claim 1, wherein: Each of the n columnar portions has a facet.

4. The light emitting device according to claim 1, wherein: When viewed from the stacking direction, The n columnar portions are arranged in a triangular lattice. The outer edge of the electrode has a first side parallel to a first line segment connecting centers of adjacent columnar portions among the n columnar portions. The center of each of the r second columnar portions overlapping the first side among the q second columnar portions overlaps the electrode.

5. The light emitting device according to claim 4, wherein: When viewed from the stacking direction, The outer edge of the electrode has a second side parallel to the first side, The center of each of the s second columnar portions overlapping the second side among the q second columnar portions overlaps the electrode.

6. The light emitting device according to claim 4, wherein: When viewed from the stacking direction, The light emitting device comprises t third columnar portions which do not overlap with the electrode. The t third columnar portions surround the n columnar portions.

7. The light emitting device according to claim 6, wherein: When viewed from the stacking direction, The outer edge of the electrode has a third side perpendicular to the first side, The third side passes through between the first columnar portion and the third columnar portion that are adjacent to each other in the direction of the first side among the p first columnar portions and the t third columnar portions. The center of each of u second columnar portions overlapping the third side among the q second columnar portions overlaps with the electrode.

8. The light emitting device according to any one of claims 1 to 7, wherein: When viewed from the stacking direction, The outer edge of each of the n columnar portions is hexagonal.

9. A projector, wherein: This projector has the light emitting device according to any one of claims 1 to 8.

Images