Light-emitting device and image display device

Abstract

A light-emitting device according to one embodiment of the present disclosure comprises: a light-emitting element in which a first semiconductor layer of a first conductivity type, an active layer, and a second semiconductor layer of a second conductivity type are sequentially stacked in a first direction; an ohmic contact layer in contact with a surface of the second semiconductor layer on the side opposite to the active layer; a first electrode provided so as to be electrically connectable to the first semiconductor layer; and a second electrode provided so as to be electrically connectable to the second semiconductor layer. The ohmic contact layer is provided at a position overlapping a part of the active layer in the first direction.

Description

Light-emitting device and image display device

[0001] The present disclosure relates to a light-emitting device and an image display device including the light-emitting device.

[0002] For example, in Patent Document 1, a light-emitting element in which a first-conductivity-type semiconductor layer, an active layer, and a second-conductivity-type semiconductor layer are laminated in this order, and having a site where ion implantation is performed in at least one of the first-conductivity-type semiconductor layer and the second-conductivity-type semiconductor layer is disclosed.

[0003] Japanese Patent Application Laid-Open No. 2024-26189

[0004] By the way, in a light-emitting device using a micro LED (Light Emitting Diode), improvement of light-emitting efficiency is desired.

[0005] It is desirable to provide a light-emitting device and an image display device capable of improving light-emitting efficiency.

[0006] A light-emitting device according to an embodiment of the present disclosure includes a light-emitting element in which a first semiconductor layer of a first conductivity type, an active layer, and a second semiconductor layer of a second conductivity type are laminated in this order in a first direction, an ohmic contact layer in contact with a surface of the second semiconductor layer on the side opposite to the active layer, a first electrode provided so as to be electrically connected to the first semiconductor layer, and a second electrode provided so as to be electrically connected to the second semiconductor layer. The ohmic contact layer is provided at a position overlapping a part of the active layer in the first direction.

[0007] An image display device according to an embodiment of the present disclosure includes a light-emitting device, and as the light-emitting device, has the light-emitting device according to the embodiment of the present disclosure.

[0008] In the light-emitting device according to an embodiment of the present disclosure and the image display device according to an embodiment, current easily flows through a site where the ohmic contact layer is provided, an effect of current constriction is imparted inside the light-emitting element, non-light-emitting coupling at the end face portion of the light-emitting element is advantageously reduced, and the light-emitting efficiency of the light-emitting device can be improved.

[0009] Figure 1 is a schematic cross-sectional view of a light-emitting device according to an embodiment of the present disclosure. Figure 2 is a schematic plan view of the light-emitting device shown in Figure 1. Figure 3A is a schematic cross-sectional view showing the manufacturing process of the light-emitting device shown in Figure 1. Figure 3B is a schematic cross-sectional view showing the process following Figure 3A. Figure 3C is a schematic cross-sectional view showing the process following Figure 3B. Figure 3D is a schematic cross-sectional view showing the process following Figure 3C. Figure 3E is a schematic cross-sectional view showing the process following Figure 3D. Figure 3F is a schematic cross-sectional view showing the process following Figure 3E. Figure 3G is a schematic cross-sectional view showing the process following Figure 3F. Figure 3H is a schematic cross-sectional view showing the process following Figure 3G. Figure 3I is a schematic cross-sectional view showing the process following Figure 3H. Figure 3J is a schematic cross-sectional view showing the process following Figure 3I. Figure 3K is a schematic cross-sectional view showing the process following Figure 3J. Figure 3L is a schematic cross-sectional view showing the process following Figure 3K. Figure 4 is a schematic cross-sectional view of a light-emitting device according to Modification 1 of the present disclosure. Figure 5 is a schematic plan view of the light-emitting device shown in Figure 4. Figure 6 is a schematic cross-sectional view of the light-emitting device according to Modification 1 of the present disclosure. Figure 7 is a schematic plan view of the light-emitting device shown in Figure 6. Figure 8 is a schematic cross-sectional view of the light-emitting device according to Modification 2 of the present disclosure. Figure 9 is a schematic plan view of the light-emitting device shown in Figure 8. Figure 10 is a schematic cross-sectional view of the light-emitting device according to Modification 2 of the present disclosure. Figure 11 is a schematic plan view of the light-emitting device shown in Figure 10. Figure 12 is a schematic cross-sectional view of the light-emitting device according to Modification 3 of the present disclosure. Figure 13 is a schematic plan view of the light-emitting device shown in Figure 12. Figure 14 is a schematic cross-sectional view of the light-emitting device according to the first Modification 4 of the present disclosure. Figure 15 is a schematic plan view of the light-emitting device shown in Figure 14. Figure 16 is a schematic cross-sectional view of the light-emitting device according to the second Modification 4 of the present disclosure. Figure 17 is a schematic plan view of the light-emitting device shown in Figure 16. Figure 18 is a schematic cross-sectional view of the light-emitting device according to Modification 5 of the present disclosure. Figure 19 is a schematic plan view of the light-emitting device shown in Figure 18. Figure 20 is a schematic cross-sectional view of the light-emitting device according to Modification 6 of the present disclosure. Figure 21 is a schematic plan view of the light-emitting device shown in Figure 20. Figure 22 is a schematic cross-sectional view of the light-emitting device according to Modification 7 of the present disclosure. Figure 23 is a schematic cross-sectional view of the light-emitting device according to the first Modification 8 of the present disclosure. Figure 24 is a schematic cross-sectional view of the light-emitting device according to the second Modification 8 of the present disclosure. Figure 25 is a schematic cross-sectional view of the light-emitting device according to Modification 9 of the present disclosure.Figure 26 is a perspective view of an image display device according to Application Example 1 of this disclosure. Figure 27 is a schematic diagram showing the wiring layout of the image display device shown in Figure 26. Figure 28 is a perspective view of an image display device according to Application Example 2 of this disclosure. Figure 29 is a perspective view of the mounting substrate shown in Figure 28. Figure 30 is a perspective view of the unit substrate shown in Figure 29. Figure 31 is a diagram showing an example of an image display device according to Application Example 3 of this disclosure. Figure 32A is a front view showing an example of the appearance of a digital still camera. Figure 32B is a rear view showing an example of the appearance of a digital still camera. Figure 33 is a perspective view showing an example of the appearance of a head-mounted display. Figure 34 is a perspective view showing an example of the appearance of a television device.

[0010] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. The following description is a specific example of the present disclosure, and the present disclosure is not limited to the following embodiments. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc., of each component shown in each figure. The order of description is as follows: 1. Embodiment 1-1. Configuration of the light-emitting device 1-2. Method for manufacturing a light-emitting element 1-3. Operation and effects 2. Modifications 2-1. Modification 1 (another example of a light-emitting device) 2-2. Modification 2 (another example of a light-emitting device) 2-3. Modification 3 (another example of a light-emitting device) 2-4. Modification 4 (another example of a light-emitting device) 2-5. Modification 5 (another example of a light-emitting device) 2-6. Modification 6 (another example of a light-emitting device) 2-7. Modification 7 (another example of a light-emitting device) 2-8. Modification 8 (another example of a light-emitting device) 2-9. Modification 9 (another example of a light-emitting device) 3. Application example (example of an image display device) 4. Application examples (examples of electronic devices)

[0011] Figure 1 schematically shows an example of the cross-sectional configuration of a light-emitting device (light-emitting device 1) according to an embodiment of the present disclosure. Figure 2 schematically shows an example of the planar configuration of the light-emitting device 1 shown in Figure 1. The light-emitting device 1 is suitably applicable to an image display device called a so-called LED display (for example, the image display device 100 shown in Figure 26 later).

[0012] [1-1. Configuration of the Light-Emitting Device] The light-emitting device 1 has a stacked structure in which a support portion 30, a plurality of light-emitting portions 10, and a plurality of lenses 21 are stacked in order in the Z-axis direction, which is the thickness direction perpendicular to the XY plane, as shown in Figure 1, for example. In the light-emitting device 1, a plurality of pixels P are arranged in a two-dimensional array along the XY plane, which includes the mutually orthogonal X-axis and Y-axis directions, as shown in Figure 2, for example. Each of the plurality of pixels P is provided with, for example, one light-emitting portion 10 and one lens 21. However, a plurality of light-emitting portions 10 may be provided for a single pixel P. Or, a plurality of lenses 21 may be provided for a single pixel P.

[0013] Each of the multiple light-emitting units 10 has a light-emitting element 11, a first electrode 12, a second electrode 14, an ohmic contact layer 13, a plug electrode 15, and a pad electrode 16. The light-emitting element 11, the first electrode 12, the second electrode 14, the ohmic contact layer 13, the plug electrode 15, and the pad electrode 16 are embedded in an insulating film 180 having, for example, insulating layers 181 to 184. The first electrode 12 and the second electrode 14 are each provided so as to be electrically connectable to the light-emitting element 11.

[0014] The light-emitting element 11 is a solid-state light-emitting element that emits light in a predetermined wavelength band from its upper surface, and is, for example, an LED (Light Emitting Diode) chip. An LED chip refers to an LED that has been cut from a wafer used for crystal growth, and is not a package type covered with molded resin or the like. The LED chip is, for example, between 5 μm and 100 μm in size, and is what is known as a microLED.

[0015] The light-emitting element 11 is constructed by sequentially stacking a first semiconductor layer 111 of a first conductivity type, an active layer 112, and a second semiconductor layer 113 of a second conductivity type in the Z-axis direction, starting from the support portion 30 side. For example, the first conductivity type is n-type and the second conductivity type is p-type.

[0016] The first semiconductor layer 111 includes, for example, an n-type semiconductor, specifically, n-type gallium nitride (GaN). The active layer 112 has a multiple quantum well structure in which, for example, indium gallium nitride (InGaN) and gallium nitride (GaN) are alternately stacked, and has light-emitting regions within the layer. From the active layer 112, for example, emitted light L in the blue band from 430 nm to 500 nm is extracted. From the active layer 112, for example, light with a wavelength corresponding to the ultraviolet region (ultraviolet light) may be extracted. The second semiconductor layer 113 includes, for example, a p-type semiconductor, specifically, p-type gallium nitride (GaN). In the light-emitting element 11, the upper surface of the second semiconductor layer 113, that is, the surface of the second semiconductor layer 113 opposite to the active layer 112, is the light-emitting surface 11S1 of the light-emitting element 11. The configurations of the first semiconductor layer 111 and the second semiconductor layer 113 are not limited to those described above, as long as the first semiconductor layer 111 and the second semiconductor layer 113 have different electrical polarities. From the viewpoint of providing a current-constricting effect, it is preferable that the first semiconductor layer 111 contains an n-type semiconductor, the second semiconductor layer 113 contains a p-type semiconductor, and the second semiconductor layer 113 is provided on the light-emitting side. It is even more preferable that the first semiconductor layer 111 contains n-type gallium nitride and the second semiconductor layer 113 contains p-type gallium nitride.

[0017] The ohmic contact layer 13 is in contact with the surface of the second semiconductor layer 113 opposite to the active layer 112. The ohmic contact layer 13 is positioned to overlap a portion of the active layer 112 in the Z-axis direction. In a plan view perpendicular to the Z-axis direction, the light-emitting element 11 has a first region 201 where the ohmic contact layer 13 and the active layer 112 overlap in the Z-axis direction, and a second region 202 surrounding the first region 201. In the second region 202, the active layer 112 does not overlap with the ohmic contact layer 13 in the Z-axis direction. However, in the embodiment shown in Figure 1, the first region 201 includes the center O of the active layer 112 in a plan view perpendicular to the Z-axis direction.

[0018] For example, the ohmic contact layer 13 and the second semiconductor layer 113 contain the same semiconductor material, and the dopant concentration of the ohmic contact layer 13 is higher than that of the second semiconductor layer 113. This makes it possible to reduce the electrical contact resistance between the ohmic contact layer 13 and the second semiconductor layer 113.

[0019] The dopant concentrations of the second semiconductor layer 113 and the ohmic contact layer 13 can be measured, for example, as follows: Using a focused ion beam (FIB) method, the regions containing the second semiconductor layer 113 and the ohmic contact layer 13 are cut out from the light-emitting element 11, and these are further processed to obtain a thin film with a thickness of 100 nm or less. The thin film is then microscopically observed using a transmission electron microscope, and the dopant concentration can be measured by performing secondary ion mass spectrometry (SIMS) on the microscopically observed region.

[0020] The first electrode 12 is electrically connectable to the first semiconductor layer 111. More specifically, the upper surface of the first electrode 12 is in contact with the surface of the first semiconductor layer 111 opposite to the active layer 112. The first electrode 12 is also electrically connectable to the pad electrode 16 via a via 15V and a plug electrode 15. More specifically, the lower surface of the first electrode 12 is in contact with the upper end of the via 15V. The first electrode 12 may include, for example, a multilayer film of nickel (Ni) and gold (Au) (Ni / Au) or a transparent conductive material such as ITO. The first electrode 12 may include a metal such as titanium (Ti), titanium nitride (TiN), tantalum nitride (TaN), aluminum (Al), silver (Ag), or a multilayer film of these materials.

[0021] The second electrode 14 is provided so as to be electrically connectable to the second semiconductor layer 113. More specifically, the second electrode 14 is provided so as to be electrically connectable to the second semiconductor layer 113 via an ohmic contact layer 13. In the embodiments shown in Figures 1 and 2, the second electrode 14 is shared by a plurality of light-emitting elements 11, but is not limited to this, and a separate second electrode 14 may be provided for each light-emitting element 11. In the embodiments shown in Figures 1 and 2, the second electrode 14 is provided so as to cover a part of the light-emitting surface 11S1 of the light-emitting element 11. The second electrode 14 may contain the same material as the first electrode 12, and preferably contains a transparent conductive material. When the second electrode 14 is provided so as to cover the entire light-emitting surface 11S1 of the light-emitting element 11, the second electrode 14 contains a transparent electrode material. Examples of transparent conductive materials include ITO, indium zinc oxide (IZO), tin oxide (SnO), and titanium oxide (TiO).

[0022] The plug electrode 15 is electrically connected to the first electrode 12 via a via 15V. The plug electrode 15 and the via 15V include, for example, copper (Cu), aluminum (Al), tungsten (W), silver (Ag), or alloys thereof.

[0023] The pad electrode 16 enables electrical connection between the plug electrode 15 and the support portion 30. The pad electrode 16 includes, for example, copper (Cu), aluminum (Al), tungsten (W), silver (Ag), or alloys thereof.

[0024] Vias (e.g., via 15V) that enable electrical connection between each wiring layer include, for example, copper (Cu), aluminum (Al), tungsten (W), silver (Ag), or alloys thereof.

[0025] The insulating layer 181 has the plug electrode 15, via 15V, and pad electrode 16 embedded in it. The insulating layer 181 includes, for example, silicon oxide (SiO) or silicon nitride (SiN). The insulating layer 182 has the first electrode 12 embedded in it. The insulating layer 182 includes, for example, silicon oxide (SiO) or silicon nitride (SiN). The insulating layer 183 has the light-emitting element 11, ohmic contact layer 13, second electrode 14, and extraction electrode 17 embedded in it. The insulating layer 183 includes, for example, silicon oxide (SiO) or silicon nitride (SiN). The insulating layer 184 covering the second electrode 14 flattens the surface facing the lens 21. The insulating layer 184 includes, for example, silicon oxide (SiO) or silicon nitride (SiN).

[0026] Multiple lenses 21 are provided at corresponding positions on multiple light-emitting elements 11. Each of the multiple lenses 21 focuses or diverges the light L emitted from the corresponding light-emitting element 11. Each of the multiple lenses 21 is made of a light-transmitting material. Each of the multiple lenses 21 includes, for example, silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiCN), and resin. Although Figures 1 and 2 show an example configuration in which one lens 21 is provided for one light-emitting element 11, this embodiment is not limited to this. For example, one lens 21 may be provided for multiple light-emitting elements 11.

[0027] The support portion 30 includes, for example, a support layer 31 and a plurality of pad portions 32 embedded in the support layer 31. The support layer 31 includes, for example, silicon oxide (SiO) or silicon nitride (SiN). Each of the plurality of pad portions 32 is provided to be electrically connectable to the pad electrode 16. Each of the plurality of pad portions 32 includes, for example, copper (Cu), aluminum (Al), tungsten (W), silver (Ag), or an alloy thereof.

[0028] [1-2. Method for Manufacturing a Light-Emitting Device] The light-emitting unit 10 in the light-emitting device 1 of this embodiment can be manufactured, for example, as follows. Figures 3A to 3L show an example of the manufacturing process for the light-emitting unit 10.

[0029] First, as shown in Figure 3A, a sapphire substrate is prepared as the growth substrate 116. Then, the first electrode 12, the first semiconductor layer 111, the active layer 112, the second semiconductor layer 113, and the ohmic contact layer 13 are sequentially formed on the growth substrate 116 by epitaxial crystal growth using methods such as metal-organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). Through these operations, a laminate 118 of the growth substrate 116, the first electrode 12, the first semiconductor layer 111, the active layer 112, the second semiconductor layer 113, and the ohmic contact layer 13 is obtained. In a subsequent step, multiple light-emitting elements 11 are obtained by cutting this laminate 118.

[0030] Next, as shown in Figure 3B, a plurality of resists R1 are formed on the upper surface of the ohmic contact layer 13 of the laminate 118. The positions where the resists R1 are formed are the positions where the ohmic contact layer 13 is provided in the light-emitting element 11 obtained by cutting the laminate 118. Subsequently, as shown in Figure 3C, the ohmic contact layer 13 is removed using the resists R1 as a mask, for example, by reactive ion etching (RIE).

[0031] Next, as shown in Figure 3D, the laminate 118 is cleaved by, for example, reactive ion etching (RIE) to obtain multiple light-emitting elements 11. During cleavage, a mesa shape is formed on the light-emitting elements 11. After that, as shown in Figure 3E, the growth substrate 116 is removed by, for example, reactive ion etching.

[0032] Next, as shown in Figure 3F, an insulating layer 183 is formed around the first electrode 12, the light-emitting element 11, and the ohmic contact layer 13. Then, as shown in Figure 3G, the upper part of the insulating layer 183 is flattened down to the surface of the ohmic contact layer 13.

[0033] Next, as shown in Figure 3H, the first electrode 12 is cut into the desired shape by processing the lower part of the insulating layer 183. Then, as shown in Figure 3I, the second electrode 14 is attached.

[0034] Next, as shown in Figure 3J, an insulating layer 184 is formed on the upper part of the insulating layer 183 and the second electrode 14 to flatten the surface S1 facing the lens 21. Then, as shown in Figure 3K, an insulating layer 182 is formed on the lower part of the first semiconductor layer 111 and the insulating layer 183 to flatten the bottom surface S2 of the first electrode 12.

[0035] Next, as shown in Figure 3L, the upper surface of the insulating layer 181, in which the plug electrode 15 and pad electrode 16 are embedded, is bonded to the surface S2 of the insulating layer 182. The support layer 31 is pre-bonded to the lower surface of the insulating layer 181. After that, the lens 21 is attached to the upper surface S1 of the insulating layer 184. Subsequently, the extraction electrode 17 (not shown, see Figure 1) is attached using a well-known method, and the light-emitting device 1 shown in Figure 1 is completed.

[0036] [1-3. Function and Effects] The light-emitting device 1 of this embodiment comprises a light-emitting element 11 in which a first semiconductor layer 111 of a first conductivity type, an active layer 112, and a second semiconductor layer 113 of a second conductivity type are stacked sequentially in the Z-axis direction, an ohmic contact layer 13 in contact with the surface of the second semiconductor layer 113 opposite to the active layer 112, a first electrode 12 electrically connectable to the first semiconductor layer 111, and a second electrode 14 electrically connectable to the second semiconductor layer 113. The ohmic contact layer 13 overlaps with a part of the active layer 112 in the Z-axis direction. This improves the luminescence efficiency of the light-emitting element 11. This will be explained below.

[0037] In general, in light-emitting devices equipped with LEDs, non-luminescent coupling can occur during light emission operation due to various crystal damages present on the LED end faces, resulting in a decrease in luminous efficiency. This decrease in luminous efficiency due to damage to the LED end faces is particularly common in light-emitting devices equipped with micro-LEDs, which are smaller than conventional LEDs.

[0038] One way to solve the above problem is to impart a current-constricting effect to the light-emitting element.

[0039] In the light-emitting device 1 of this embodiment, a current flows inside the light-emitting element 11 due to the potential difference between the first electrode 12 and the second electrode 14. In the light-emitting device 1, the ohmic contact layer 13 is provided in a position that overlaps with a part of the active layer 112 in the Z-axis direction. Therefore, current flows more easily to the portion of the light-emitting element 11 that occupies the first region 201 where the ohmic contact layer 13 is provided. Consequently, a current-constricting effect can be applied to the light-emitting element 11, and non-luminescent coupling at the end face of the light-emitting element 11 can be reduced. As a result, the luminescence efficiency of the light-emitting element 11 can be improved. In the light-emitting device 1 shown in Figures 1 and 2, since the first region 201 in which the ohmic contact layer 13 and the active layer 112 overlap in the Z-axis direction includes point O, non-luminescent coupling at the end face of the light-emitting element 11 can be reduced particularly advantageously, and as a result, the luminescence efficiency of the light-emitting device 1 can be improved particularly advantageously.

[0040] <2. Modifications> Next, Modifications 1 to 9 of the present disclosure and examples of their application will be described. Note that the same reference numerals are used for components corresponding to the light-emitting device 1 of the above embodiment, and their descriptions are omitted.

[0041] [2-1. Modification 1] Figure 4 schematically shows an example of the cross-sectional configuration of the first light-emitting device (light-emitting device 1A-1) according to Modification 1 of the present disclosure. Figure 5 schematically shows an example of the planar configuration of the light-emitting device 1A-1 shown in Figure 4. Figure 6 schematically shows an example of the cross-sectional configuration of the second light-emitting device (light-emitting device 1A-2) according to Modification 1 of the present disclosure. Figure 7 schematically shows an example of the planar configuration of the light-emitting device 1A-2 shown in Figure 6.

[0042] In the above embodiment, an example was shown in which the first region 201, in a plan view perpendicular to the Z-axis direction, where the ohmic contact layer 13 and the active layer 112 overlap in the Z-axis direction, includes the center O of the active layer 112. However, this disclosure is not limited thereto. As shown in Figures 4 and 5, in the light-emitting device 1A-1 of this modified example 1, the second region 202 includes the edge of the active layer 112 in a plan view perpendicular to the Z-axis direction (see Figure 5). Also, as shown in Figures 6 and 7, in the light-emitting device 1A-2 of this modified example 1, there are no particular restrictions on the relationship between the first region 201 and the second region 202 and the active layer 112 in a plan view perpendicular to the Z-axis direction. For example, the first region 201 includes the edge of the active layer 112 (see Figure 7). In both the light-emitting device 1A-1 and the light-emitting device 1A-2, the ohmic contact layer 13 is provided in a position that overlaps with a part of the active layer 112 in the Z-axis direction. Compared to light-emitting device 1, in light-emitting devices 1A-1 and 1A-2, the area where current flows easily is somewhat offset from the central axis parallel to the Z-axis passing through the center O of the active layer 112, but a current-constricting effect can be applied to the light-emitting element 11. As a result, in light-emitting devices 1A-1 and 1A-2, non-luminescent coupling at the end face of the light-emitting element 11 can be advantageously reduced, and as a result, the luminescence efficiency can be advantageously improved.

[0043] [2-2. Modification 2] Figure 8 schematically shows an example of the cross-sectional configuration of the first light-emitting device (light-emitting device 1B-1) according to Modification 2 of the present disclosure. Figure 9 schematically shows an example of the planar configuration of the light-emitting device 1B-1 shown in Figure 8. Figure 10 schematically shows an example of the cross-sectional configuration of the second light-emitting device (light-emitting device 1B-2) according to Modification 2 of the present disclosure. Figure 11 schematically shows an example of the planar configuration of the light-emitting device 1B-2 shown in Figure 10.

[0044] In the above-described embodiment, an example was shown in which the second electrode 14 does not contact the surface of the second semiconductor layer 113 on the side opposite to the active layer 112. However, the present disclosure is not limited to this. In the light-emitting devices 1B-1 and 1B-2 of this modification 2, as shown in FIGS. 8 and 10, the second electrode 14 extends from the surface of the ohmic contact layer 13 on the side opposite to the second semiconductor layer 113 to the surface of the second semiconductor layer 113 on the side opposite to the active layer 112. In both the light-emitting device 1B-1 and the light-emitting device 1B-2, as shown in FIGS. 9 and 11, since the second electrode 14 does not cover the entire light-emitting surface 11S1 of the light-emitting element 11, the emitted light L from the active layer 112 can be extracted. From the viewpoint of extracting the emitted light L, the second electrode 14 is preferably a transparent electrode 18. In the light-emitting device 1B-1, the second electrode 14 is shared by adjacent light-emitting elements 11, and in the light-emitting device 1B-2, the second electrode 14 is shared by three or more light-emitting elements 11. However, the present disclosure is not limited to this, and a separate second electrode 14 may be provided for each light-emitting element 11.

[0045] Except for the above points, the configurations of the light-emitting devices 1B-1 and 1B-2 are substantially the same as the configuration of the light-emitting device 1 according to the above-described embodiment. Even in the light-emitting devices 1B-1 and 1B-2 having such a configuration, the same effects as those of the light-emitting device 1 according to the above-described embodiment can be obtained.

[0046] [2-3. Modification 3] FIG. 12 schematically shows an example of a cross-sectional configuration of a light-emitting device (light-emitting device 1C) according to Modification 3 of the present disclosure. FIG. 13 schematically shows an example of a planar configuration of the light-emitting device 1C shown in FIG. 12.

[0047] In the above-described embodiment, an example in which the light-emitting device 1 includes the second electrode 14 provided so as to be electrically connected to the second semiconductor layer 113 via the ohmic contact layer 13 has been shown. However, the present disclosure is not limited to this. As shown in FIG. 12, the light-emitting device 1C of this modification further includes a transparent electrode 18 provided on the surface of the second electrode 14 opposite to the ohmic contact layer 13. Thereby, the transparent electrode 18 can cause a current to flow through the second electrode 14 and the ohmic contact layer 13 to the light-emitting element 11. In the light-emitting device 1C, as shown in FIG. 13, the transparent electrode 18 is provided so as to cover a part of the light-emitting surface 11S1 of the light-emitting element 11, but it may be provided so as to cover all of it. The transparent electrode 18 may contain, for example, one or more selected from the group consisting of ITO, indium zinc oxide (IZO), tin oxide (SnO), and titanium oxide (TiO).

[0048] Except for the above points, the configuration of the light-emitting device 1C is substantially the same as the configuration of the light-emitting device 1 according to the above-described embodiment. Even in the light-emitting device 1C having such a configuration, the same effects as those of the light-emitting device 1 according to the above-described embodiment can be obtained.

[0049] [2-4. Modification 4]FIG. 14 schematically shows an example of a cross-sectional configuration of a first light-emitting device (light-emitting device 1D-1) according to Modification 4 of the present disclosure. FIG. 15 schematically shows an example of a planar configuration of the light-emitting device 1D-1 shown in FIG. 14. FIG. 16 schematically shows an example of a cross-sectional configuration of a second light-emitting device (light-emitting device 1D-2) according to Modification 4 of the present disclosure. FIG. 17 schematically shows an example of a planar configuration of the light-emitting device 1D-2 shown in FIG. 16.

[0050] In Modification 3, the light-emitting device 1C further includes a transparent electrode 18 provided on the surface of the second electrode 14 opposite to the ohmic contact layer 13, and the transparent electrode 18 is not in contact with the surface of the second semiconductor layer 113 opposite to the active layer 112. However, the disclosure is not limited thereto. In the light-emitting devices 1D-1 and 1D-2 of Modification 4, the transparent electrode 18 extends from the surface of the second electrode 14 opposite to the ohmic contact layer 13 to the surface of the second semiconductor layer 113 opposite to the active layer 112. In addition, in the light-emitting device 1D-2, the transparent electrode 18 covers the entire second semiconductor layer 113 in a plan view perpendicular to the Z-axis direction, and the surface of the transparent electrode 18 opposite to the second semiconductor layer 113 is flat. In the light-emitting device 1D-1, the transparent electrode 18 is shared by adjacent light-emitting elements 11, but the disclosure is not limited thereto, and a transparent electrode 18 may be provided for each light-emitting element 11. In the light-emitting device 1D-2, three or more light-emitting elements 11 share a transparent electrode 18, but this is not limited to this, and adjacent light-emitting elements 11 may also share a transparent electrode 18. In both the light-emitting device 1D-1 and the light-emitting device 1D-2, the second electrode 14 is provided so as to be electrically connectable to the extraction electrode 17 via the transparent electrode 18. In both configurations of the light-emitting device 1D-1 and the light-emitting device 1D-2, almost no current flows in the portion of the transparent electrode 18 that is in direct contact with the surface of the second semiconductor layer 113 opposite to the active layer 112, without going through the ohmic contact layer 13, and the current flows through the ohmic contact layer 13. This makes it possible to impart a current-constricting effect to the light-emitting elements 11.

[0051] Except for the points mentioned above, the configurations of the light-emitting devices 1D-1 and 1D-2 are substantially the same as those of the light-emitting device 1 according to the above embodiment. Even with such configurations, the same effects as those of the light-emitting device 1 according to the above embodiment can be obtained.

[0052] [2-5. Modification 5] Figure 18 schematically shows an example of the cross-sectional configuration of the light-emitting device (light-emitting device 1E) according to Modification 5 of the present disclosure. Figure 19 schematically shows an example of the planar configuration of the light-emitting device 1E shown in Figure 18.

[0053] In the above embodiment, an example was shown in which the second semiconductor layer 113 in contact with the ohmic contact layer 13 has a simple mesa shape, but the disclosure is not limited thereto. In the light-emitting device 1E of this modified example 5, as shown in Figures 18 and 17, the thickness of the first portion 201a occupying the first region 201 of the second semiconductor layer 113 is greater than the thickness of the second portion 202a occupying the second region 202 of the second semiconductor layer 113. As a result, the path through which current flows within the second semiconductor layer 113 is narrowed in the first portion 201a compared to the second portion 202a, the current constriction effect is strengthened throughout the light-emitting element 11, and non-luminescent coupling at the end face of the light-emitting element 11 can be further reduced. The thickness of the first portion 201a and the thickness of the second portion 202a are thicknesses in the Z-axis direction.

[0054] Except for the points mentioned above, the configuration of the light-emitting device 1E is substantially the same as the configuration of the light-emitting device 1 according to the above embodiment. The same effects as those of the light-emitting device 1 according to the above embodiment can be obtained even with a light-emitting device 1E having such a configuration.

[0055] [2-6. Modification 6] Figure 20 schematically shows an example of the cross-sectional configuration of the light-emitting device (light-emitting device 1F) according to Modification 6 of the present disclosure. Figure 21 schematically shows an example of the planar configuration of the light-emitting device 1F shown in Figure 20.

[0056] In the light-emitting device 1E according to Modification 5, an example is shown in which the thickness of the first portion 201a occupying the first region 201 of the second semiconductor layer 113 is greater than the thickness of the second portion 202a occupying the second region 202 of the second semiconductor layer 113, but the present disclosure is not limited thereto. The light-emitting device 1F according to Modification 6 of the present disclosure further includes, in addition to the light-emitting device 1E according to Modification 5, a translucent material layer 19 provided in the second region 202 so as to cover the surface of the second portion 202a opposite to the active layer 112. As a result, when the emitted light L emitted from the active layer 112 passes through the second semiconductor layer 113 and enters the translucent material layer 19, the direction of the emitted light L can be controlled by the refractive index of the translucent material layer 19.

[0057] If the refractive index of the translucent material layer 19 is higher than that of the second semiconductor layer 113, the emitted light L from the active layer 112 will have difficulty passing through the second semiconductor layer 113 and entering the translucent material layer 19. This makes it possible to strengthen the directivity of the emitted light L from the active layer 112. When the refractive index of the translucent material layer 19 is higher than that of the second semiconductor layer 113, for example, the second semiconductor layer 113 contains gallium nitride, and the translucent material layer 19 contains one or more selected from the group consisting of gallium arsenide, indium phosphide, titanium dioxide, and strontium titanate.

[0058] If the refractive index of the translucent material layer 19 is lower than that of the second semiconductor layer 113, the emitted light L from the active layer 112 is more likely to pass through the second semiconductor layer 113 and enter the translucent material layer 19. This makes it possible to weaken the directivity of the emitted light L from the active layer 112. When the translucent material layer 19 has a refractive index lower than that of the second semiconductor layer 113, for example, the second semiconductor layer 113 contains gallium nitride, and the translucent material layer 19 contains one or more selected from the group consisting of silicon dioxide, magnesium fluoride, aluminum oxide, polymethyl methacrylate, polycarbonate, lithium fluoride, and calcium fluoride.

[0059] Except for the points mentioned above, the configuration of the light-emitting device 1F is substantially the same as the configuration of the light-emitting device 1 according to the above embodiment. Even with a light-emitting device 1F having such a configuration, the same effects as the light-emitting device 1 according to the above embodiment can be obtained.

[0060] [2-7. Modification 7] Figure 22 schematically shows an example of the cross-sectional configuration of a light-emitting device (light-emitting device 1G) according to Modification 7 of the present disclosure.

[0061] In the light-emitting device 1E according to Modification 5, an example is shown in which the second semiconductor layer 113 has a first portion 201a occupying the first region 201 and a second portion 202a occupying the second region 202 (see Figures 18 and 19), but the present disclosure is not limited thereto. In the light-emitting device 1G according to Modification 7 of the present disclosure, as shown in Figure 22, the second semiconductor layer 113 is provided only in the first portion 201a of the first region 201. As a result, the path through which current flows inside the second semiconductor layer 113 is further narrowed, and the current constriction effect is further strengthened throughout the light-emitting element 11. As a result, non-luminescent coupling at the end face of the light-emitting device 1G can be further reduced.

[0062] Except for the points mentioned above, the configuration of the light-emitting device 1G is substantially the same as the configuration of the light-emitting device 1 according to the above embodiment. Even with a light-emitting device 1G having such a configuration, the same effects as the light-emitting device 1 according to the above embodiment can be obtained.

[0063] [2-8. Modification 8] Figure 23 schematically shows an example of the cross-sectional configuration of the first light-emitting device (light-emitting device 1H-1) according to Modification 8 of the present disclosure. Figure 24 schematically shows an example of the cross-sectional configuration of the second light-emitting device (light-emitting device 1H-2) according to Modification 8 of the present disclosure.

[0064] In the light-emitting device 1G according to Modification 7, an example is shown in which the second semiconductor layer 113 is provided only in the first portion 201a of the first region 201, but the present disclosure is not limited thereto. In the light-emitting device 1H-1 according to Modification 8 of the present disclosure, in addition to the light-emitting device 1G according to Modification 7, a stopper layer 115 having conductivity, light transmission, and etching resistance is further provided between the active layer 112 and the second semiconductor layer 113. In the light-emitting device 1H-1 according to Modification 8, for example, the second semiconductor layer 113 is processed and removed to the side of the active layer 112 opposite to the first semiconductor layer 111 by etching, but by providing the stopper layer 115, the possibility of the active layer 112 being damaged when the second semiconductor layer 113 is processed and removed can be reduced. The stopper layer 115 is more difficult to remove by processing, such as etching, than the second semiconductor layer 113. In addition, the conductivity of the stopper layer 115 ensures that current flows within the light-emitting element 11, and the light-transmitting properties of the stopper layer 115 ensure that light emitted from the active layer 112 is extracted. For example, if the second semiconductor layer 113 contains gallium nitride (GaN), the stopper layer 115 may contain aluminum gallium nitride (AlGaN) or the like.

[0065] Except for the points mentioned above, the configuration of the light-emitting device 1H-1 is substantially the same as the configuration of the light-emitting device 1 according to the above embodiment. Even with a light-emitting device 1H-1 having such a configuration, the same effects as the light-emitting device 1 according to the above embodiment can be obtained.

[0066] Furthermore, in the light-emitting device 1H-1, an example was shown in which, when the second semiconductor layer 113 is provided only in the first region 201, a stopper layer 115 having conductivity, light transmission, and etching resistance is further provided between the active layer 112 and the second semiconductor layer 113, but the disclosure is not limited thereto. In the light-emitting device 1H-2 shown in Figure 24, a third semiconductor layer 114 of the second conductivity type is further provided between the active layer 112 and the stopper layer 115. The third semiconductor layer 114 may be of the second conductivity type, and it is preferable that the third semiconductor layer 114 contains the same material as the second semiconductor layer 113. Thus, except for the provision of the stopper layer 115, the configuration of the light-emitting device 1H-2 of this modified example 8 is substantially the same as the configuration of the light-emitting device 1E of modified example 5.

[0067] Except for the points mentioned above, the configurations of the light-emitting devices 1H-1 and 1H-2 are substantially the same as those of the light-emitting device 1 according to the above embodiment. Even with such configurations, the same effects as those of the light-emitting device 1 according to the above embodiment can be obtained with the light-emitting devices 1H-1 and 1H-2.

[0068] [2-9. Modification 9] Figure 25 schematically shows an example of the cross-sectional configuration of a light-emitting device (light-emitting device 1J) according to Modification 9 of the present disclosure.

[0069] In the light-emitting device 1E of Modification 5, an example is shown where the thickness of the first portion 201a occupying the first region 201 of the second semiconductor layer 113 is thicker than the thickness of the second portion 202a occupying the second region 202 of the second semiconductor layer 113, but the present disclosure is not limited thereto. In the light-emitting device 1J of Modification 9, as shown in Figure 25, the thickness of the third portion 201b occupying the first region 201 of the first semiconductor layer 111 is thicker than the thickness of the fourth portion 202b occupying the second region 202 of the first semiconductor layer 111. As a result, in the third portion 201b occupying the first region 201 of the first semiconductor layer 111, the path through which current flows within the first semiconductor layer 111 is narrowed, the current constriction effect is strengthened throughout the light-emitting element 11, and non-luminescent coupling at the end face of the light-emitting device 1J can be reduced. In the light-emitting device 1J shown in Figure 25, the thickness of the third portion 201b occupying the first region 201 of the first semiconductor layer 111 is greater than the thickness of the fourth portion 202b occupying the second region 202 of the first semiconductor layer 111. However, for example, in addition to that, the thickness of the first portion 201a occupying the first region 201 of the second semiconductor layer 113 may also be greater than the thickness of the second portion 202a occupying the second region 202 of the second semiconductor layer 113.

[0070] Except for the points mentioned above, the configuration of the light-emitting device 1J is substantially the same as the configuration of the light-emitting device 1 in the above embodiment. The same effects as in the above embodiment can be obtained even with a light-emitting device 1J having such a configuration.

[0071] <3. Application Examples> (Application Example 1) Figure 26 is a perspective view showing an example of the schematic configuration of an image display device (image display device 100). The image display device 100 is a so-called LED display, and the light-emitting device of this disclosure (for example, light-emitting device 1) is used as the display pixel. The image display device 100 includes, for example, a display panel 120 and a control circuit 140 that drives the display panel 120, as shown in Figure 26.

[0072] The display panel 120 consists of a mounting substrate 120A and an opposing substrate 120B superimposed on each other. The surface of the opposing substrate 120B serves as the image display surface, with a display area (display section 100A) in the center and a non-display area, the frame section 100B, surrounding it.

[0073] Figure 27 shows an example of the wiring layout of the area corresponding to the display unit 100A on the surface of the mounting substrate 120A on the opposing substrate 120B side. On the surface of the mounting substrate 120A, in the area corresponding to the display unit 100A, a plurality of data wirings 134 are formed extending in a predetermined direction and arranged in parallel at a predetermined pitch, as shown in Figure 27. On the surface of the mounting substrate 120A, in the area corresponding to the display unit 100A, a plurality of scan wirings 135 are formed extending in a direction intersecting (for example, orthogonal to) the data wirings 134 and arranged in parallel at a predetermined pitch. The data wirings 134 and scan wirings 135 are made of a conductive material such as Cu.

[0074] The scan wiring 135 is formed, for example, on the outermost layer, and is formed on an insulating layer (not shown) formed on the surface of the substrate. The substrate of the mounting board 120A is made of, for example, a silicon substrate or a resin substrate, and the insulating layer on the substrate is made of, for example, SiN, SiO, aluminum oxide (AlO), or a resin material. On the other hand, the data wiring 134 is formed in a layer different from the outermost layer containing the scan wiring 135 (for example, a layer below the outermost layer), and is formed, for example, in an insulating layer on the substrate.

[0075] The vicinity of the intersection of the data wiring 134 and the scan wiring 135 is a display pixel 136, and multiple display pixels 136 are arranged in a matrix within the display unit 100A. Each display pixel 136 is equipped with, for example, the respective color pixels Pr, Pg, and Pb of the light-emitting device 1.

[0076] The light-emitting device 1 is provided with terminal electrodes, for example, one pair for each color pixel Pr, Pg, and Pb, or one common electrode and the other arranged for each color pixel Pr, Pg, and Pb. One terminal electrode is electrically connectable to the data wiring 134, and the other terminal electrode is electrically connectable to the scan wiring 135. For example, one terminal electrode is electrically connectable to the pad electrode 134B at the tip of a branch 134A provided on the data wiring 134. Also, for example, the other terminal electrode is electrically connectable to the pad electrode 135B at the tip of a branch 135A provided on the scan wiring 135.

[0077] Each pad electrode 134B, 135B is formed, for example, on the outermost layer and is provided in the area where each light-emitting device 1 is mounted, as shown in Figure 26. Here, the pad electrodes 134B, 135B are made of a conductive material such as Au (gold).

[0078] The mounting substrate 120A is further provided with a plurality of support columns (not shown) that, for example, regulate the distance between the mounting substrate 120A and the opposing substrate 120B. The support columns may be provided in the area facing the display unit 100A, or in the area facing the frame unit 100B.

[0079] The opposing substrate 120B is made of, for example, a glass substrate or a resin substrate. On the opposing substrate 120B, the surface on the side facing the light-emitting device 1 may be flat, but it is preferable that it be rough. The rough surface may be provided over the entire area facing the display unit 100A, or it may be provided only in the area facing the display pixels 136. The rough surface has fine irregularities that allow light emitted from the color pixels Pr, Pg, and Pb to enter the rough surface. The irregularities of the rough surface can be created, for example, by sandblasting or dry etching.

[0080] The control circuit 140 drives each display pixel 136 (each light-emitting device 1) based on the video signal. The control circuit 140 is composed of, for example, a data driver that drives data wiring 134 connected to the display pixel 136, and a scan driver that drives scan wiring 135 connected to the display pixel 136. The control circuit 140 may be provided separately from the display panel 120 and connected to the mounting board 120A via wiring, or it may be mounted on the mounting board 120A, as shown in Figure 13.

[0081] (Application Example 2) Figure 28 is a perspective view showing another configuration example (image display device 200) of an image display device using the light-emitting device of this disclosure (for example, light-emitting device 1). The image display device 200 is a so-called tiling display that uses a plurality of light-emitting devices with LEDs as light sources. The image display device 200 includes, for example, a display panel 220 and a control circuit 240 that drives the display panel 220, as shown in Figure 28.

[0082] The display panel 220 consists of a mounting substrate 220A and an opposing substrate 220B superimposed on each other. The surface of the opposing substrate 220B serves as the image display surface, with a display area in the center and a frame area surrounding it, which is a non-display area (neither of which is shown). The opposing substrate 220B is positioned opposite the mounting substrate 220A, for example, with a predetermined gap between them. The opposing substrate 220B may also be in contact with the upper surface of the mounting substrate 220A.

[0083] Figure 29 schematically shows an example of the configuration of the mounting board 220A. The mounting board 220A is composed of multiple unit boards 250 arranged in a tile-like pattern, as shown in Figure 29. Although Figure 29 shows an example in which the mounting board 220A is composed of nine unit boards 250, the number of unit boards 250 may be 10 or more, or 8 or less.

[0084] Figure 30 shows an example of the configuration of a unit board 250. The unit board 250 has, for example, a plurality of light-emitting devices 1 arranged in a tile-like pattern, and a support board 260 that supports each light-emitting device 1. Each unit board 250 further has a control board (not shown). The support board 260 is made of, for example, a metal frame (metal plate) or a wiring board. If the support board 260 is made of a wiring board, it can also serve as the control board. In this case, at least one of the support board 260 and the control board is provided so as to be electrically connectable to each light-emitting device 1.

[0085] (Application Example 3) Figure 31 shows the appearance of the transparent display 300. The transparent display 300 includes, for example, a display unit 310, an operation unit 311, and a housing 312. The display unit 310 uses the light-emitting device of this disclosure (for example, light-emitting device 1). This transparent display 300 is capable of displaying images and text information while allowing the background of the display unit 310 to pass through.

[0086] In the transparent display 300, the mounting substrate is a light-transmitting substrate. Each electrode provided on the light-emitting device 1 is formed using a conductive material that is light-transmitting, similar to the mounting substrate. Alternatively, each electrode is designed to be difficult to see by reducing the width of the wiring or the thickness of the wiring. Furthermore, the transparent display 300 can display black by, for example, layering a liquid crystal layer equipped with a driving circuit, and switching between transmission and black display is possible by controlling the light distribution direction of the liquid crystal.

[0087] <4. Application Examples> An image display device (e.g., image display device 100) using the light-emitting device of this disclosure (e.g., light-emitting device 1) described above may be provided in various electronic devices. It is particularly preferable that it be provided in devices that require high resolution and are used with magnification close to the eyes, such as the electronic viewfinder of a video camera or SLR camera, or a head-mounted display.

[0088] (Specific Example 1) Figure 32A is a front view showing an example of the external appearance of the digital still camera 340. Figure 32B is a rear view showing an example of the external appearance of the digital still camera 340. This digital still camera 340 is a single-lens reflex type with interchangeable lenses, and has an interchangeable shooting lens unit (interchangeable lens) 342 located approximately in the center of the front of the camera body 341, and a grip portion 343 for the photographer to hold on the left side of the front.

[0089] A monitor 344 is located slightly to the left of the center of the back of the camera body 341. An electronic viewfinder (eyepiece) 345 is provided above the monitor 344. The photographer can determine the composition by looking through the electronic viewfinder 345 and visually confirming the light image of the subject guided by the shooting lens unit 342. The electronic viewfinder 345 is equipped with an image display device 100.

[0090] (Specific Example 2) Figure 33 is a perspective view showing an example of the appearance of a head-mounted display 320. The head-mounted display 320 has, for example, a glasses-shaped display unit 321 and ear hooks 322 on both sides for being attached to the user's head. The display unit 321 includes an image display device 100.

[0091] (Specific Example 2) Figure 34 is a perspective view showing an example of the appearance of a television device 330. This television device 330 has, for example, a video display screen section 331 including a front panel 332 and a filter glass 333, and this video display screen section 331 includes an image display device (for example, an image display device 100) using a light-emitting device (for example, light-emitting device 1) of the present disclosure.

[0092] The present technology has been described above with reference to embodiments and modifications 1 to 9 and application examples. However, the present technology is not limited to the above embodiments, and various modifications are possible. For example, the above embodiments show examples in which the light emitted from the active layer 112 is blue light or ultraviolet light, but the technology is not limited to these. For example, the light-emitting device 1 can also use a light-emitting element that emits two or more types of light, such as blue light and green light, or ultraviolet light and green light.

[0093] Furthermore, although the above embodiments have described the components constituting the light-emitting device 1 and the like in detail, it is not necessary to include all components, and other components may also be included.

[0094] Furthermore, although the above embodiments illustrate cases where the drive circuit and the like are provided outside the light-emitting device, this disclosure is not limited thereto. The light-emitting device 1 may, for example, have the drive circuit provided inside the support portion 30, and the drive circuit and the light-emitting element 11 may be electrically connectable.

[0095] Furthermore, the effects described herein are merely examples and are not limited to those described; other effects may also occur.

[0096] The present technology can also take the following configurations. According to the present technology with the following configurations, current flows easily to the area where the ohmic contact layer is provided, imparting a current-constricting effect to the inside of the light-emitting element, thereby advantageously reducing non-luminescent coupling at the end face of the light-emitting element. As a result, the luminous efficiency of the light-emitting device can be improved. (1) A light-emitting element comprising: a first semiconductor layer of a first conductivity type, an active layer, and a second semiconductor layer of a second conductivity type stacked in order in a first direction; an ohmic contact layer in contact with the surface of the second semiconductor layer opposite to the active layer; a first electrode electrically connectable to the first semiconductor layer; and a second electrode electrically connectable to the second semiconductor layer, wherein the ohmic contact layer is provided in a position that overlaps with a part of the active layer in the first direction. (2) The light-emitting device according to (1), having, in a plan view perpendicular to the first direction, a first region in which the ohmic contact layer and the active layer overlap in the first direction, and a second region surrounding the first region. (3) The light-emitting device according to (2), wherein the second region includes the edge of the active layer in a plan view perpendicular to the first direction. (4) The light-emitting device according to (2), wherein the first region includes the center of the active layer in a plan view perpendicular to the first direction. (5) The light-emitting device according to any one of (1) to (4), wherein the ohmic contact layer and the second semiconductor layer contain the same semiconductor material, and the dopant concentration of the ohmic contact layer is higher than the dopant concentration of the second semiconductor layer. (6) The light-emitting device according to any one of (1) to (5), wherein the second electrode extends from the surface of the ohmic contact layer opposite to the second semiconductor layer to the surface of the second semiconductor layer opposite to the active layer. (7) The light-emitting device according to any one of (1) to (6), further comprising a transparent electrode provided on the surface of the second electrode opposite to the ohmic contact layer. (8) The light-emitting device according to (7), wherein the transparent electrode extends from the surface of the second electrode opposite to the ohmic contact layer to the surface of the second semiconductor layer opposite to the active layer.(9) The light-emitting device according to (8), wherein in a plan view perpendicular to the first direction, the transparent electrode covers the entirety of the second semiconductor layer, and the surface of the transparent electrode opposite to the second semiconductor layer is flat. (10) The light-emitting device according to (2), wherein the thickness of the first portion of the second semiconductor layer occupying the first region is greater than the thickness of the second portion of the second semiconductor layer occupying the second region. (11) The light-emitting device according to (10), further comprising a translucent material layer provided in the second region so as to cover the surface of the second portion opposite to the active layer. (12) The light-emitting device according to (2), wherein the second semiconductor layer is provided only in the first region. (13) The light-emitting device according to (12), further comprising a stopper layer having conductivity, translucency, and etching resistance between the active layer and the second semiconductor layer. (14) The light-emitting device according to (13), further comprising a third semiconductor layer of the second conductivity type between the active layer and the stopper layer. (15) The light-emitting device according to (2), wherein the thickness of the third portion occupying the first region of the first semiconductor layer is greater than the thickness of the fourth portion occupying the second region of the first semiconductor layer. (16) The light-emitting device according to any one of (1) to (15), wherein the first conductivity type is n type and the second conductivity type is p type, and the second semiconductor layer includes the light-emitting surface of the light-emitting element. (17) The light-emitting device according to (16), wherein each of the first semiconductor layer and the second semiconductor layer contains gallium nitride. (18) The light-emitting device according to (11), wherein the refractive index of the translucent material layer is higher than the refractive index of the second semiconductor layer. (19) The light-emitting device according to (18), wherein the second semiconductor layer contains gallium nitride, and the translucent material layer contains one or more selected from the group consisting of gallium arsenide, indium phosphide, titanium dioxide, and strontium titanate. (20) The light-emitting device according to (11), wherein the refractive index of the light-transmitting material layer is lower than the refractive index of the second semiconductor layer.(21) The light-emitting device according to (20), wherein the second semiconductor layer contains gallium nitride, and the translucent material layer contains one or more selected from the group consisting of silicon dioxide, magnesium fluoride, aluminum oxide, polymethyl methacrylate, polycarbonate, lithium fluoride, and calcium fluoride. (22) An image display device comprising a light-emitting device, wherein the light-emitting device comprises a light-emitting element in which a first semiconductor layer of a first conductivity type, an active layer, and a second semiconductor layer of a second conductivity type are stacked in order in a first direction, an ohmic contact layer in contact with the surface of the second semiconductor layer opposite to the active layer, a first electrode electrically connectable to the first semiconductor layer, and a second electrode electrically connectable to the second semiconductor layer, wherein the ohmic contact layer is provided in a position that overlaps with a part of the active layer in the first direction.

[0097] This application claims priority based on Japanese Patent Application No. 2025-002990, filed with the Japan Patent Office on 8 January 2025, and all contents of that application are incorporated herein by reference.

[0098] Those skilled in the art will understand that various modifications, combinations, subcombinations, and changes can be conceived depending on design requirements and other factors, and that these fall within the scope of the attached claims and their equivalents.

Claims

1. A light-emitting device comprising: a first semiconductor layer of a first conductivity type, an active layer, and a second semiconductor layer of a second conductivity type stacked in order in a first direction; an ohmic contact layer in contact with the surface of the second semiconductor layer opposite to the active layer; a first electrode electrically connectable to the first semiconductor layer; and a second electrode electrically connectable to the second semiconductor layer, wherein the ohmic contact layer is provided in a position that overlaps with a part of the active layer in the first direction.

2. The light-emitting device according to claim 1, having a first region in which the ohmic contact layer and the active layer overlap in the first direction when viewed in a plan view perpendicular to the first direction, and a second region surrounding the first region.

3. The light-emitting device according to claim 2, wherein the second region includes the edge of the active layer in a plan view perpendicular to the first direction.

4. The light-emitting device according to claim 2, wherein the first region includes the center of the active layer in a plan view perpendicular to the first direction.

5. The light-emitting device according to claim 1, wherein the ohmic contact layer and the second semiconductor layer contain the same semiconductor material, and the dopant concentration of the ohmic contact layer is higher than the dopant concentration of the second semiconductor layer.

6. The light-emitting device according to claim 1, wherein the second electrode extends from the surface of the ohmic contact layer opposite to the second semiconductor layer to the surface of the second semiconductor layer opposite to the active layer.

7. The light-emitting device according to claim 1, further comprising a transparent electrode provided on the surface of the second electrode opposite to the ohmic contact layer.

8. The light-emitting device according to claim 7, wherein the transparent electrode extends from the surface of the second electrode opposite to the ohmic contact layer to the surface of the second semiconductor layer opposite to the active layer.

9. The light-emitting device according to claim 8, wherein in a plan view perpendicular to the first direction, the transparent electrode covers the entirety of the second semiconductor layer, and the surface of the transparent electrode opposite to the second semiconductor layer is flat.

10. The light-emitting device according to claim 2, wherein the thickness of the first portion occupying the first region of the second semiconductor layer is greater than the thickness of the second portion occupying the second region of the second semiconductor layer.

11. The light-emitting device according to claim 10, further comprising a translucent material layer provided in the second region so as to cover the surface of the second portion opposite to the active layer.

12. The light-emitting device according to claim 2, wherein the second semiconductor layer is provided only in the first region.

13. The light-emitting device according to claim 12, further comprising a stopper layer having conductivity, light transmission, and etching resistance between the active layer and the second semiconductor layer.

14. The light-emitting device according to claim 13, further comprising a third semiconductor layer of the second conductivity type between the active layer and the stopper layer.

15. The light-emitting device according to claim 2, wherein the thickness of the third portion occupying the first region of the first semiconductor layer is greater than the thickness of the fourth portion occupying the second region of the first semiconductor layer.

16. The light-emitting device according to claim 1, wherein the first conductivity type is n-type and the second conductivity type is p-type, and the second semiconductor layer includes the light-emitting surface of the light-emitting element.

17. The light-emitting apparatus according to claim 16, wherein each of the first semiconductor layer and the second semiconductor layer comprises gallium nitride.

18. The light-emitting device according to claim 11, wherein the refractive index of the light-transmitting material layer is higher than the refractive index of the second semiconductor layer.

19. The light-emitting device according to claim 18, wherein the second semiconductor layer contains gallium nitride, and the light-transmitting material layer contains one or more selected from the group consisting of gallium arsenide, indium phosphide, titanium dioxide, and strontium titanate.

20. The light-emitting device according to claim 11, wherein the refractive index of the light-transmitting material layer is lower than the refractive index of the second semiconductor layer.

21. The light-emitting device according to claim 20, wherein the second semiconductor layer contains gallium nitride, and the light-transmitting material layer contains one or more selected from the group consisting of silicon dioxide, magnesium fluoride, aluminum oxide, polymethyl methacrylate, polycarbonate, lithium fluoride, and calcium fluoride.

22. An image display device comprising a light-emitting device, the light-emitting device comprising a light-emitting element in which a first semiconductor layer of a first conductivity type, an active layer, and a second semiconductor layer of a second conductivity type are stacked in order in a first direction, an ohmic contact layer in contact with the surface of the second semiconductor layer opposite to the active layer, a first electrode provided to be electrically connectable to the first semiconductor layer, and a second electrode provided to be electrically connectable to the second semiconductor layer, wherein the ohmic contact layer is provided in a position that overlaps with a part of the active layer in the first direction.

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