Light-emitting device and image display device

Abstract

A light-emitting device according to one embodiment of the present disclosure comprises: a first compound semiconductor layer having a mutually opposing first surface and second surface and having at least one first raised and recessed structure on the first surface; a second compound semiconductor layer having a third surface that faces the first surface and a fourth surface on the reverse side from the third surface, and having, on the third surface, a second raised and recessed structure that fits together with the first raised and recessed structure; and a light-emitting layer provided between the first compound semiconductor layer and the second compound semiconductor layer.

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 same.

[0002] For example, Patent Document 1 discloses a semiconductor light emitting device in which an n-type GaN layer is processed into a hexagonal shape, and an active layer and a p-type GaN layer are grown in this order to cover the center of the hexagon.

[0003] WO 2004 / 023569

[0004] Meanwhile, in micro-sized displays, there is a demand for improved luminous efficiency.

[0005] It is desirable to provide a light emitting device and an image display device that can improve the light emitting efficiency.

[0006] A light-emitting device according to one embodiment of the present disclosure includes: a first compound semiconductor layer having opposing first and second surfaces and having at least one first uneven structure on the first surface; a second compound semiconductor layer having a third surface facing the first surface and a fourth surface opposite the third surface and having a second uneven structure on the third surface that fits into the first uneven structure; and a light-emitting layer disposed between the first compound semiconductor layer and the second compound semiconductor layer.

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

[0008] In the light-emitting device and the image display device according to an embodiment of the present disclosure, a first compound semiconductor layer and a second compound semiconductor layer are provided on their opposing surfaces (the first surface of the first compound semiconductor layer and the third surface of the second compound semiconductor layer) with interlocking concave-convex structures, and a light-emitting layer is provided between the first compound semiconductor layer and the second compound semiconductor layer, extending along the concave-convex structures, thereby suppressing diffusion of carriers in the planar direction within the light-emitting layer.

[0009] FIG. 1 is a cross-sectional view schematically illustrating an example of a configuration of a light-emitting device according to a first embodiment of the present disclosure. FIG. 2 is an exploded perspective view of the light-emitting device shown in FIG. 1. FIG. 3 is a plan view schematic illustrating a layout of a concavo-convex structure of the light-emitting device shown in FIG. 1. FIG. 4 is a diagram illustrating an example of a change in thickness of a second cladding layer within the surface of the light-emitting device shown in FIG. 1. FIG. 5 is a diagram illustrating another example of a change in thickness of the second cladding layer within the surface of the light-emitting device shown in FIG. 1. FIG. 6 is a diagram illustrating another example of a change in thickness of the second cladding layer within the surface of the light-emitting device shown in FIG. 1. FIG. 7 is a diagram illustrating another example of a change in thickness of the second cladding layer within the surface of the light-emitting device shown in FIG. 1. FIG. 8 is a diagram illustrating another example of a change in thickness of the second cladding layer within the surface of the light-emitting device shown in FIG. 1. FIG. 9 is a diagram illustrating another example of a change in thickness of the second cladding layer within the surface of the light-emitting device shown in FIG. 1. FIG. 10 is a diagram illustrating another example of a change in thickness of the second cladding layer within the surface of the light-emitting device shown in FIG. 1. FIG. 11 is a cross-sectional view schematically illustrating an example of a configuration of a light-emitting device according to a second embodiment of the present disclosure.

[0033] Fig. 12 is an exploded perspective view of the light-emitting device shown in Fig. 11. Fig. 13 is a plan view schematic diagram showing the layout of the concavo-convex structure of the light-emitting device shown in Fig. 11. Fig. 14 is a diagram illustrating an example of a change in the thickness of the second cladding layer within the plane of the light-emitting device shown in Fig. 11. Fig. 15 is a plan view schematic diagram showing an example of the layout of the concavo-convex structure of a light-emitting device according to Modification 1 of the present disclosure. Fig. 16 is a plan view schematic diagram showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 1 of the present disclosure. Fig. 17 is a plan view schematic diagram showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 1 of the present disclosure. Fig. 18 is a plan view schematic diagram showing an example of the layout of the concavo-convex structure of a light-emitting device according to Modification 2 of the present disclosure. Fig. 19 is a plan view schematic diagram showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 2 of the present disclosure. Fig. 20 is a plan view schematic diagram showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 2 of the present disclosure. Fig. 21 is a plan view schematic diagram showing an example of the layout of the concavo-convex structure of a light-emitting device according to Modification 3 of the present disclosure.FIG. 22 is a schematic plan view showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 3 of the present disclosure. FIG. 23 is a schematic plan view showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 3 of the present disclosure. FIG. 24 is a schematic plan view showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 3 of the present disclosure. FIG. 25 is a schematic plan view showing another example of the layout of the concavo-convex structure of a light-emitting device according to Modification 3 of the present disclosure. FIG. 26 is a schematic cross-sectional view showing an example of the configuration of a light-emitting device according to Modification 4 of the present disclosure. FIG. 27 is a schematic cross-sectional view showing another example of the configuration of a light-emitting device according to Modification 4 of the present disclosure. FIG. 28 is a schematic cross-sectional view showing another example of the configuration of a light-emitting device according to Modification 4 of the present disclosure. FIG. 29 is a schematic cross-sectional view showing an example of the configuration of a light-emitting device according to Modification 5 of the present disclosure. FIG. 30 is a schematic cross-sectional view showing an example of the configuration of a light-emitting device according to Modification 6 of the present disclosure. FIG. 31 is a schematic cross-sectional view showing an example of the configuration of a light-emitting device according to Modification 7 of the present disclosure. FIG. 32 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 7 of the present disclosure. FIG. 33 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to Modification 8 of the present disclosure. FIG. 34 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to Modification 9 of the present disclosure. FIG. 35 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 9 of the present disclosure. FIG. 36 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 9 of the present disclosure. FIG. 37 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to Modification 10 of the present disclosure. FIG. 38 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 10 of the present disclosure. FIG. 39 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 10 of the present disclosure. FIG. 40 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 10 of the present disclosure. FIG. 41 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 10 of the present disclosure. FIG. 42 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 10 of the present disclosure. Fig. 43 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 10 of the present disclosure. Fig. 44 is a cross-sectional view schematically illustrating another example of the configuration of a light-emitting device according to Modification 10 of the present disclosure.Fig. 45 is a perspective view illustrating an example of the configuration of an image display device according to an application example of the present disclosure. Fig. 46 is a perspective view illustrating another example of the configuration of an image display device according to an application example of the present disclosure.

[0010] Hereinafter, an 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 aspect. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The description will be given in the following order: 1. First embodiment (example of a light-emitting device having a plurality of concave-convex structures) 2. Second embodiment (example of a light-emitting device having one convex portion and a refractive index variation region surrounding it) 3. Modification 1 (another example of a light-emitting device) 4. Modification 2 (another example of a light-emitting device) 5. Modification 3 (another example of a light-emitting device) 6. Modification 4 (another example of a light-emitting device) 7. Modification 5 (another example of a light-emitting device) 8. Modification 6 (another example of a light-emitting device) 9. Modification 7 (another example of a light-emitting device) 10. Modification 8 (another example of a light-emitting device) 11. Modification 9 (another example of a light-emitting device) 12. Modification 10 (another example of a light-emitting device) 13. Application example (example of an image display device)

[0011] 1. Embodiments Fig. 1 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 1 according to a first embodiment of the present disclosure. Fig. 2 is an exploded perspective view of the light-emitting device 1 illustrated in Fig. 1. Fig. 3 is a schematic diagram illustrating, for example, a planar layout of recesses 11X and protrusions 11Y of a first cladding layer 11 of the light-emitting device 1 illustrated in Fig. 1. The light-emitting device 1 is, for example, a light-emitting element having an element size of 10 μm or less, and is suitable for use in a display unit 1210 of an image display device (e.g., a head-mounted display 1000, see Fig. 45 ).

[0012] [Configuration of Light-Emitting Device] The light-emitting device 1 is formed by laminating a first cladding layer 11, a light-emitting layer 12, and a second cladding layer 13 in this order. The light-emitting device 1 has a light-emitting surface on the second cladding layer 13 side. The first cladding layer 11 has a pair of opposing surfaces (surfaces 11S1 and 11S2), and the surface 11S2 facing the second cladding layer 13 has an uneven structure consisting of a plurality of recesses 11X and a plurality of protrusions 11Y in a cross-sectional view. The second cladding layer 13 has a pair of opposing surfaces (surfaces 13S1 and 13S2), and the surface 13S1 facing the first cladding layer 11 has an uneven structure consisting of a plurality of recesses 13X and a plurality of protrusions 13Y that fit with the uneven structure of the first cladding layer 11 in a cross-sectional view. The light-emitting layer 12 extends between the first cladding layer 11 and the second cladding layer 13 along the concavo-convex structures of the first cladding layer 11 and the second cladding layer 13. Although not shown in Fig. 1, electrodes 31 and 32 are provided on a surface 11S1 of the first cladding layer 11 and a surface 13S2 of the second cladding layer 13, respectively (see Fig. 33).

[0013] The first cladding layer 11 corresponds to a specific example of a "first compound semiconductor layer" in an embodiment of the present disclosure, and is formed of, for example, an n-type GaN-based compound semiconductor material. Alternatively, the first cladding layer 11 can be formed of, for example, an n-type P-based compound semiconductor material such as AlGaInP or GaInP.

[0014] The light-emitting layer 12 emits and amplifies spontaneously emitted light, and generates stimulated emission light by radiative recombination of holes and electrons injected from the electrodes 31 and 32. The light-emitting layer 12 has, for example, a multiple quantum well (MQW) structure in which a plurality of quantum well layers and a plurality of barrier layers are alternately stacked. In the light-emitting device 1, the light-emitting layer 12 is formed by stacking, for example, a quantum well layer 121, a barrier layer 122, a quantum well layer 223, a barrier layer 124, and a quantum well layer 125 in this order, and is provided between the first cladding layer 11 and the second cladding layer 13.

[0015] The second cladding layer 13 corresponds to a specific example of a "second compound semiconductor layer" in an embodiment of the present disclosure, and is formed, for example, from a p-type GaN-based compound semiconductor material. Alternatively, the second cladding layer 13 can be formed, for example, from a p-based compound semiconductor material such as p-type AlGaInP or GaInP. The second cladding layer 13 has a surface 13S2 opposite to a surface 13S1 facing the light-emitting layer 12, which serves as a light-emitting surface.

[0016] The light-emitting device 1 has an internal uneven structure. Specifically, as shown in FIGS. 1 to 3 , the surface 11S2 of the first cladding layer 11 has an uneven structure including, for example, 3×3 convex portions 11Y arranged in the row direction (X-axis direction) and the column direction (Y-axis direction) at a pitch of, for example, 700 nm or less, and concave portions 11X formed around the convex portions 11Y. The light-emitting layer 12 extends on the surface 11S2 of the first cladding layer 11 with a substantially constant thickness along the concave-convex structure of the first cladding layer 11. The second cladding layer 13 is stacked on the light-emitting layer 12 so as to fill the concave portions 11X of the first cladding layer 11. That is, the second cladding layer 13 has an uneven structure on the surface 13S1 facing the first cladding layer 11 that fits into the concave-convex structure of the first cladding layer 11.

[0017] Fig. 4 illustrates the change in thickness of the second cladding layer 13 within the plane of the light-emitting device 1 shown in Fig. 1. In the light-emitting device 1 having a flat surface (surface 13S2) of the second cladding layer 13 as shown in Fig. 1, the thickness of the second cladding layer 13 within the XY plane is, for example, thinnest at the convex portion 11Y of the first cladding layer 11, gradually increases from the boundary between the convex portion 11Y and the concave portion 11X of the first cladding layer 11 toward the bottom of the concave portion 11X, and is thickest at the bottom of the concave portion 11X of the first cladding layer 11.

[0018] Here, the "thickness" refers to the thickness in the direction normal to the surface 13S2 of the second cladding layer 13. The recess 11X of the first cladding layer 11 corresponds to a specific example of a "first recess" in an embodiment of the present disclosure, and the protrusion 11Y corresponds to a specific example of a "first protrusion" in an embodiment of the present disclosure. The recess 13X of the second cladding layer 13 corresponds to a specific example of a "second recess" in an embodiment of the present disclosure, and the protrusion 13Y corresponds to a specific example of a "second protrusion" in an embodiment of the present disclosure.

[0019] Furthermore, when the change in thickness of the second cladding layer 13 within the plane of the light-emitting device 1 (within the XY plane in FIG. 1 ) is viewed in the direction of the arrow in the figure, the thickness ai of the second cladding layer 13 within the recess 11X of the first cladding layer 11 is greater than the thickness a0 of the second cladding layer 13 within the protrusion 11Y of the first cladding layer 11 (ai > a0). The thickness ai of the second cladding layer 13 within the recess 11X of the first cladding layer 11 gradually increases on the inclined surface from near the boundary between the recess 11X and the protrusion 11Y of the first cladding layer 11 toward the bottom of the recess 11X, and is maximum at the bottom of the recess 11X of the first cladding layer 11. The thickness ai of the second cladding layer 13, which is maximum at the bottom of the recess 11X of the first cladding layer 11, gradually decreases along the inclined plane from the bottom of the recess 11X of the first cladding layer 11 toward the vicinity of the boundary between the recess 11X and the protrusion 11Y, and becomes minimum near the boundary between the recess 11X and the protrusion 11Y. Thus, the recess 11X of the first cladding layer 11 has an inflection point where the thickness ai of the second cladding layer 13 changes from increasing to decreasing, as well as a maximum point and a minimum point.

[0020] Fig. 5 schematically shows another example of the concave-convex structure of the first cladding layer 11 and the second cladding layer 13. Figs. 1 and 4 show an example in which the bottom of the recess 11X of the first cladding layer 11 is flat. However, as shown in Fig. 5, if the bottom of the recess 11X of the first cladding layer 11 is inclined, for example, toward the center, the thickness ai of the second cladding layer 13 in the recess 11X of the first cladding layer 11 changes as follows. For example, the thickness ai of the second cladding layer 13 in the recess 11X of the first cladding layer 11 gradually increases in accordance with the inclination angle on the inclined surface extending from the vicinity of the boundary between the protrusion 11Y and the recess 11X of the first cladding layer 11 toward the bottom of the recess 11X, as in Fig. 4. Furthermore, the thickness ai of the second cladding layer 13 in the recess 11X of the first cladding layer 11 gradually increases in accordance with the inclination angle on the inclined surface from near the boundary between the inclined surface and the bottom of the recess 11X toward the bottommost part of the recess 11X, and is maximum at the bottommost part of the recess 11X. The thickness ai of the second cladding layer 13, which is maximum at the bottommost part of the recess 11X of the first cladding layer 11, gradually decreases in accordance with the inclination angle from the bottommost part of the recess 11X toward near the boundary between the bottom of the recess 11X and the inclined surface of the recess 11X. Furthermore, the thickness ai of the second cladding layer 13 in the recess 11X of the first cladding layer 11 gradually decreases in accordance with the inclination angle on the inclined surface from near the boundary between the bottom of the recess 11X and the inclined surface toward near the boundary between the recess 11X and the protrusion 11Y, and is minimum near the boundary between the recess 11X and the protrusion 11Y. That is, if the thickness at the boundary between the convex portion 11Y and the concave portion 11X of the first cladding layer 11 (in other words, the thickness at the convex portion 11Y of the first cladding layer 11) is a0, the thickness from near the boundary between the convex portion 11Y and the concave portion 11X to near the boundary with the bottom of the concave portion 11X is a1, the thickness near the boundary with the bottom of the concave portion 11X is a2, and the thickness at the very bottom of the concave portion 11X is a3, then a0 < a1 < a2 < a3 (maximum).

[0021] 6 to 10 are schematic diagrams showing other examples of the shape of the surface (surface 13S2) of the second cladding layer 13. While Figures 4 and 5 show examples in which the surface 13S2 of the second cladding layer 13 is flat, the surface 13S2 of the second cladding layer 13 does not necessarily have to be flat.

[0022] 6 , a recess 13Z1 may be formed above the recess 11X of the first cladding layer 11 on the surface 13S2 of the second cladding layer 13. When the recess 13Z1 is formed above the recess 11X, the thickness ai of the second cladding layer 13 in the recess 11X of the first cladding layer 11 satisfies ai>a0 when the difference b between the bottom surface of the recess 13X and the top surface of the protrusion 13Y of the concave-convex structure of the second cladding layer 13 that fits into the concave-convex structure of the first cladding layer 11 is greater than the depth c of the recess 13Z1 (b>c) and further the width d of the bottom surface of the first recess is smaller than twice the thickness a0 of the second cladding layer 13 at the protrusion 11Y of the first cladding layer 11 (d / 2<a0). The difference b between the bottom surface of the recess 13X and the top surface of the protrusion 13Y of the uneven structure of the second cladding layer 13 that fits into the uneven structure of the first cladding layer 11 corresponds to the thickness of the second cladding layer 13 embedded in the recess 11X.

[0023] When the surface 13S2 of the second cladding layer 13 is flat as shown in FIGS. 4 and 5, b>c=0, and when d / 2<a0, ai>a0.

[0024] 7, the bottom surface of the recess 11X of the first cladding layer 11 may be inclined toward the center, and a recess 13Z1 may be formed on the surface 13S2 of the second cladding layer 13 above the recess 11X of the first cladding layer 11. In this way, even when the bottom surface of the recess 11X of the first cladding layer 11 is inclined toward the center, and a recess 13Z1 is formed on the surface 13S2 of the second cladding layer 13 above the recess 11X of the first cladding layer 11, the configuration is the same as that shown in FIG. That is, the thickness ai of the second cladding layer 13 in the recess 11X of the first cladding layer 11 satisfies ai>a0 when the difference b between the bottom surface of the recess 13X of the uneven structure of the second cladding layer 13 that fits into the uneven structure of the first cladding layer 11 and the top surface of the protrusion 13Y is greater than the depth c of the depression 13Z1 (b>c), and further the width d of the bottom surface of the first recess is smaller than twice the thickness a0 of the second cladding layer 13 at the protrusion 11Y of the first cladding layer 11 (d / 2<a0).

[0025] 8, a protrusion 13Z2 may be formed above the recess 11X of the first cladding layer 11 on the surface 13S2 of the second cladding layer 13. When the protrusion 13Z2 is formed above the recess 11X, and the height −c of the protrusion is smaller than the difference b between the bottom surface of the recess 13X and the top surface of the protrusion 13Y of the concave-convex structure of the second cladding layer 13 that fits into the concave-convex structure of the first cladding layer 11 (b>−c), and further the width d of the bottom surface of the first recess is smaller than twice the thickness a0 of the second cladding layer 13 at the protrusion 11Y of the first cladding layer 11 (d / 2<a0), then ai>a0 holds.

[0026] 9, a protrusion 13Z2 may be formed above the inclined surface of the recess 11X of the first cladding layer 11 on the surface 13S2 of the second cladding layer 13. Even when the protrusion 13Z2 is formed above the inclined surface of the recess 11X, if the height −c of the protrusion is smaller than the difference b between the bottom surface of the recess 13X and the top surface of the protrusion 13Y of the recess / protrusion structure of the second cladding layer 13 that fits into the recess / protrusion structure of the first cladding layer 11 (b>−c), and further if the width d of the bottom surface of the first recess is smaller than twice the thickness a0 of the second cladding layer 13 at the protrusion 11Y of the first cladding layer 11 (d / 2<a0), then ai>a0 holds.

[0027] 6 and 7 may be formed so as to be shifted from the crystal growth orientation (the direction of the dotted arrow in the figure), as shown in Fig. 10. Similarly, the protrusion 13Z2 of the surface 13S2 of the second cladding layer 13 shown in Fig. 8 may be formed so as to be shifted from the crystal growth orientation (the direction of the dotted arrow in the figure). In either case, the thickness ai of the second cladding layer 13 in the recess 11X of the first cladding layer 11 satisfies the relationship ai > a0, even when the amount of shift of the recess 13Z1 or the protrusion 13Z2 is taken into consideration.

[0028] [Method for Manufacturing a Light-Emitting Device] The uneven structure of the first cladding layer 11 can be formed, for example, by combining photolithography with wet etching or dry etching. The light-emitting layer 12 and the second cladding layer 13 can be formed, for example, by epitaxial crystal growth using a method such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The second cladding layer 13 can be grown to a predetermined thickness by epitaxial crystal growth, and then its surface can be planarized by, for example, chemical mechanical polishing (CMP).

[0029] [Functions and Effects] In the light-emitting device 1 of the present embodiment, a surface 11S2 of the first cladding layer 11 facing the second cladding layer 13 is provided with a concave-convex structure consisting of a plurality of convex portions 11Y and concave portions 11X provided around the convex portions 11Y, and a surface 13S1 of the second cladding layer 13 facing the first cladding layer 11 is provided with a concave-convex structure consisting of a plurality of concave portions 13X and convex portions 13Y provided around the convex portions 13X, which fit into the concave-convex structure of the first cladding layer 11. The light-emitting layer 12 is provided between the first cladding layer 11 and the second cladding layer 13, extending along the respective concave-convex structures. This suppresses lateral diffusion of carriers within the light-emitting layer 12 (e.g., in the XY plane). This is described below.

[0030] In micro-sized panel light sources (hereinafter referred to as microdisplays) used in organic or inorganic electroluminescence (EL) displays and the like, the pixels are becoming increasingly miniaturized, and in response to this, development of micro-sized light-emitting elements using high-brightness LEDs is progressing.

[0031] However, simply reducing the size of elements such as micro-sized light-emitting diodes (LEDs) increases the proportion of the end face in the light-emitting area, which causes a significant decrease in light-emitting efficiency and leads to deterioration of the consumption electrode in products using such elements.

[0032] In contrast to this, in the present embodiment, a fitting concave-convex structure is provided on the opposing surfaces 11S2 and 13S1 of the first cladding layer 11 and the second cladding layer 13, and the light-emitting layer 12 extending along the concave-convex structure is provided between the first cladding layer 11 and the second cladding layer 13. As a result, a step is formed in the XY plane direction in which the light-emitting layer 12 extends.

[0033] The following formulas (1) to (3) represent the drift current J ｄｒｉｆｔ (Equation (1)), the diffusion coefficient D (Equation (2)) and the diffusion current J ｄｉｆｆｕｓｉｏｎ This shows the formula for determining (Equation (3)).

[0034] (q: carrier charge [C], n: carrier density function [ / m ３ ], μ: carrier mobility [m ２ / Vs], E: electric field strength [V / m], k: Boltzmann constant [eV / K], T: temperature [K], D: diffusion coefficient [m ２ / s])

[0035] The diffusion coefficient D and carrier mobility μ are linked by the Einstein relationship. Forming a step in the horizontal direction (XY plane direction) along which the light-emitting layer 12 extends increases the distance that carriers travel in the horizontal direction. Furthermore, the uneven structure in the XY plane direction causes spatial fluctuations in the electric field strength (E), and the drift current is rate-determined in areas where the electric field strength (E) is low. As a result, variations in carrier density n occur in the uneven portions, and the diffusion current, which is determined by the magnitude of the carrier density, is inhibited, slowing down the drift current and diffusion current in the XY directions. This suppresses the diffusion of carriers in the plane direction within the light-emitting layer 12.

[0036] As described above, the light-emitting device 1 of the present embodiment can improve the light-emitting efficiency, and therefore, an image display device using the light-emitting device can achieve high brightness and low power consumption.

[0037] Furthermore, in this embodiment, a concave-convex structure consisting of a plurality of convex portions 11Y and concave portions 11X provided around the convex portions 11Y is provided on the surface 11S2 of the first cladding layer 11 facing the second cladding layer 13, and a concave-convex structure consisting of a plurality of concave portions 13X and convex portions 13Y provided around the convex portions 11X, which fit into the concave-convex structure of the first cladding layer 11, is provided on the surface 13S1 of the second cladding layer 13 facing the first cladding layer 11, so that the steps of the light-emitting layer 12 extending along the concave-convex structure of the first cladding layer 11 are embedded with the second cladding layer 13. This reduces the proportion of the end faces in the light-emitting area compared to a light-emitting device simply having a reduced element size. This reduces carrier loss due to non-emission from the end faces, thereby improving light-emitting efficiency.

[0038] Next, a second embodiment of the present disclosure and modifications 1 to 10 will be described. Note that components corresponding to those in the light-emitting device 1 of the first embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0039] 2. Second Embodiment Fig. 11 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 2 according to a second embodiment of the present disclosure. Fig. 12 is an exploded perspective view of the light-emitting device 2 illustrated in Fig. 11. Fig. 13 is a schematic diagram illustrating, for example, a planar layout of the recesses 21X and the protrusions 21Y of the first cladding layer 21 of the light-emitting device 2 illustrated in Fig. 11. The light-emitting device 2 is suitable for use in, for example, a display unit 1210 of an image display device (e.g., a head-mounted display 1000, see Fig. 45 ).

[0040] [Configuration of Light-Emitting Device] The light-emitting device 2 includes a first cladding layer 21, a light-emitting layer 22, and a second cladding layer 23 stacked in this order. The light-emitting device 2 has a light-emitting surface on the second cladding layer 23 side. The first cladding layer 21 has a pair of opposing surfaces (surfaces 21S1 and 21S2). The surface 21S2 facing the second cladding layer 23 has a concave-convex structure consisting of a single convex portion 21Y and a concave portion 21X provided around the convex portion 21Y. A current constriction region 211 is formed within the first cladding layer 21. The second cladding layer 23 has a pair of opposing surfaces (surfaces 23S1 and 23S2). The surface 23S1 facing the first cladding layer 21 has a concave-convex structure consisting of a single concave portion 23X and a convex portion 23Y provided around the concave portion 23X. The concave-convex structure fits into the concave-convex structure of the first cladding layer 21. A plurality of grooves 23Z are provided on the surface 23S2 side of the second cladding layer 23. In a plan view, the plurality of grooves 23Z are periodically arranged around one convex portion 21Y provided in the first cladding layer 21, thereby constituting a periodic refractive index varying region 23A. The light emitting layer 22 extends between the first cladding layer 21 and the second cladding layer 23 along the respective concave-convex structures of the first cladding layer 21 and the second cladding layer 23. Although not shown in FIG. 11 , electrodes 31 and 32 are provided on the surface 21S1 of the first cladding layer 21 and the surface 23S2 of the second cladding layer 23, respectively (see FIG. 33 ).

[0041] The first cladding layer 21 corresponds to a specific example of a "first compound semiconductor layer" in an embodiment of the present disclosure, and is formed, for example, from an n-type GaN-based compound semiconductor material. Alternatively, the first cladding layer 21 can be formed, for example, from a P-based compound semiconductor material such as n-type AlGaInP or GaInP. A current confinement region 211 is provided within the first cladding layer 21.

[0042] The current confinement region 211 provides a confinement effect to the current. In plan view, the current confinement region 211 is formed at a position corresponding to a recess 21X provided around one protrusion 21Y provided at approximately the center of the first cladding layer 21. The current confinement region 21B has insulating properties and can be formed, for example, by ion implantation of impurities from the surface (e.g., surface 21S1) side of the first cladding layer 21. Alternatively, the current confinement region 21B can be formed by oxidizing the side surface of the first cladding layer 21. By providing the current confinement region 211, the current injected from the electrode 31 to the light-emitting layer 22 is confined, thereby improving the current injection efficiency.

[0043] The light-emitting layer 22 emits and amplifies spontaneously emitted light, and generates stimulated emission light by radiative recombination of holes and electrons injected from the electrodes 31 and 32. The light-emitting layer 22 has, for example, a multiple quantum well (MQW) structure in which a plurality of quantum well layers and a plurality of barrier layers are alternately stacked. In the light-emitting device 2, the light-emitting layer 22 is formed by stacking, for example, a quantum well layer 221, a barrier layer 222, a quantum well layer 223, a barrier layer 224, and a quantum well layer 225 in this order, and is provided between the first cladding layer 21 and the second cladding layer 23. The light-emitting layer 22 has a light-emitting region therein corresponding to the current confinement region 211 formed in the first cladding layer 21.

[0044] The second cladding layer 23 corresponds to a specific example of a "second compound semiconductor layer" in an embodiment of the present disclosure and is formed, for example, from a p-type GaN-based compound semiconductor material. Alternatively, the second cladding layer 23 can be formed, for example, from a p-type P-based compound semiconductor material such as p-type AlGaInP or GaInP. The second cladding layer 23 has a surface 23S2 opposite to a surface 23S1 facing the light-emitting layer 22 as a light-emitting surface. A plurality of grooves 23Z are periodically arranged on the surface 23S2 above a recess 21X provided around one protrusion 21Y in the first cladding layer 21, thereby constituting a refractive index varying region 23A.

[0045] The refractive index varying region 23A, which is made up of the plurality of grooves 23Z, has a structure that suppresses the diffusion of light in the in-plane direction by the photonic crystal and improves the efficiency of light extraction from the light emitting surface (surface 23S1). The period at which the plurality of grooves 23Z are formed and the refractive index are appropriately designed according to the wavelength of the light emitted from the light emitting layer 22.

[0046] Fig. 14 illustrates the change in thickness of the second cladding layer 23 within the plane of the light-emitting device 2 shown in Fig. 11. In the light-emitting device 2 in which the surface (surface 23S2) of the second cladding layer 13 is flat except for the plurality of grooves 23Z, similar to the light-emitting device 1 of the first embodiment, the thickness of the second cladding layer 23 within the XY plane is, for example, thinnest at the convex portions 21Y of the first cladding layer 21, gradually thickens from the boundary between the convex portions 21Y and the concave portions 21X of the first cladding layer 21 toward the bottom of the concave portions 21X, and is thickest at the bottom of the concave portions 21X of the first cladding layer 21.

[0047] Here, the "thickness" refers to the thickness in the direction normal to the surface 13S2 of the second cladding layer 23. The recess 21X of the first cladding layer 21 corresponds to a specific example of a "first recess" in an embodiment of the present disclosure, and the protrusion 21Y corresponds to a specific example of a "second protrusion" in an embodiment of the present disclosure. The recess 23X of the second cladding layer 23 corresponds to a specific example of a "second recess" in an embodiment of the present disclosure, and the protrusion 23Y corresponds to a specific example of a "second protrusion" in an embodiment of the present disclosure.

[0048] Furthermore, when the change in the thickness of the second cladding layer 23 within the plane of the light-emitting device 1 is viewed in the direction of the arrow in the figure, the thickness ai of the second cladding layer 23 at the recessed portion 21X of the first cladding layer 21 is greater than the thickness a0 of the second cladding layer 23 at the protruding portion 21Y of the first cladding layer 21 (ai > a0). The thickness ai of the second cladding layer 23 at the recessed portion 21X of the first cladding layer 21 gradually increases on the inclined surface from near the boundary between the recessed portion 21X and the protruding portion 21Y of the first cladding layer 21 toward the bottom of the recessed portion 21X, and is maximum at the bottom of the recessed portion 21X of the first cladding layer 21.

[0049] In the first embodiment, the thickness ai of the second cladding layer 13 has an inflection point where it changes from increasing to decreasing, as well as a maximum point and a minimum point, in the plurality of recesses 11X provided on the surface 11S1 of the first cladding layer 11. In contrast to this, in the light-emitting device 2 in the present embodiment, in which one convex portion 21Y is provided on the surface 21S1 of the first cladding layer 21 and recesses 21X are provided around the convex portion 21Y, it can be said that the thickness gi of the second cladding layer 23 has an inflection point where it changes from increasing to decreasing, as well as a maximum point and a minimum point, in the recess 23X of the second cladding layer 23 that fits into the convex portion 21Y of the first cladding layer 21. That is, when the change in thickness of the first cladding layer 21 is viewed in the direction of the arrow in the figure, the thickness gi of the first cladding layer 21 at the recessed portion 23X of the second cladding layer 23 is greater than the thickness h of the first cladding layer 21 at the protruding portion 23Y of the second cladding layer 23 (gi > h). The thickness gi of the first cladding layer 21 at the recessed portion 23X of the second cladding layer 23 gradually increases on the inclined surface from near the boundary between the recessed portion 23X and the protruding portion 23Y of the second cladding layer 23 toward the bottom of the recessed portion 23X, and is maximum at the bottom of the recessed portion 23X of the second cladding layer 23.

[0050] [Operations and Effects] In the light-emitting device 2 of the present embodiment, a surface 21S2 of the first cladding layer 21 facing the second cladding layer 23 is provided with a concave-convex structure consisting of one convex portion 21Y and a concave portion 21X provided around the convex portion 21Y. A surface 23S1 of the second cladding layer 23 facing the first cladding layer 21 is provided with a concave-convex structure consisting of one concave portion 23X and a convex portion 23Y provided around the concave-convex portion 23X. The concave-convex structure fits into the concave-convex structure of the first cladding layer 21. The light-emitting layer 22 is provided between the first cladding layer 21 and the second cladding layer 23, extending along the concave-convex structures. This suppresses the diffusion of carriers in the planar direction within the light-emitting layer 22. Therefore, similar to the first embodiment, the light-emitting efficiency can be improved, and an image display device using the light-emitting layer 22 can achieve high brightness and low power consumption.

[0051] Furthermore, in this embodiment, a plurality of grooves 23Z are periodically arranged around one convex portion 11Y provided in the first cladding layer 21 in a plan view on the surface 23S2 of the second cladding layer 23, which serves as the light-emitting surface of the light-emitting device 2, to form a periodic refractive index varying region 23A. This makes it possible to improve the efficiency of light extraction to the light-emitting surface side. Therefore, it is possible to achieve even higher brightness and lower power consumption in an image display device using this.

[0052] 15 to 17 are schematic diagrams illustrating an example of a concave-convex structure (for example, a planar layout of the recesses 11X and the protrusions 11Y of the first cladding layer 11) of a light-emitting device according to a first modification of the present disclosure.

[0053] In the first embodiment described above, an example has been shown in which the surface 11S2 of the first cladding layer 11 has an uneven structure consisting of 3 × 3 convex portions 11Y in the X-axis direction and Y-axis direction and concave portions 11X provided around them, and the surface 13S1 of the second cladding layer 13 has an uneven structure consisting of 3 × 3 concave portions 13X in the X-axis direction and convex portions 13Y provided around them, which fit into the uneven structure of the first cladding layer 11. However, the layout of the concave portions 11X, 13X and the convex portions 11Y, 13Y is not limited to this.

[0054] For example, as shown in FIG. 15 , a concave-convex structure consisting of 3 × 3 recesses 11X in the X-axis direction and Y-axis direction and protrusions 11Y provided around the recesses 11X may be provided on the surface 11S2 of the first cladding layer 11, and a concave-convex structure consisting of 3 × 3 protrusions 13Y in the X-axis direction and Y-axis direction and recesses 13X provided around the protrusions 13Y may be provided on the surface 13S1 of the second cladding layer 13, which fit with the concave-convex structure of the first cladding layer 11.

[0055] For example, a concave-convex structure may be periodically provided from the center to the outside in the XY plane of the light-emitting device 1. Specifically, as shown in Fig. 16 , a plurality of mutually independent convex portions 11Y may be periodically provided on the surface 11S2 of the first cladding layer 11. Although not shown, a plurality of mutually independent concave portions 13X are periodically provided on the surface 13S2 of the second cladding layer 13 to fit with the plurality of convex portions 11Y of the first cladding layer 11.

[0056] 16 shows an example in which a plurality of protrusions 11Y are provided independent of each other, but this is not limiting, and as shown in Fig. 17, for example, a plurality of annular protrusions 11Y may be provided concentrically from the center to the outside in the XY plane of the light-emitting device 1. Although not shown, a plurality of annular recesses 13X that fit with the plurality of annular protrusions 11Y of the first cladding layer 11 are provided concentrically on the surface 13S2 of the second cladding layer 13 from the center to the outside in the XY plane of the light-emitting device 1.

[0057] Even with this configuration, the same effects as those of the first embodiment can be obtained.

[0058] 18 to 20 are schematic diagrams illustrating an example of a concave-convex structure (for example, a planar layout of the recesses 21X and protrusions 21Y of the first cladding layer 21) of a light-emitting device according to a second modification of the present disclosure.

[0059] In the second embodiment described above, an example has been shown in which a concave-convex structure consisting of one convex portion 21Y and a concave portion 21X provided around the convex portion 21Y is provided on the surface 21S2 of the first cladding layer 21, and a concave-convex structure consisting of one concave portion 23X and a convex portion 23Y provided around the convex portion 23Y that fits into the concave-convex structure of the first cladding layer 21 is provided on the surface 22S1 of the second cladding layer 23, but the layout of the concave portions 21X, 23X and the convex portions 21Y, 23Y is not limited to this.

[0060] 18 , for example, a substantially rectangular frame-shaped protrusion 21Y may be provided on the surface 21S2 of the first cladding layer 21, with recesses 11X provided inside and outside the protrusion 21Y. Although not shown, a substantially rectangular frame-shaped recess 23X that fits into the plurality of substantially rectangular frame-shaped protrusions 21Y of the first cladding layer 21 may be provided on the surface 23S2 of the second cladding layer 23, with protrusions 23Y provided inside and outside the recess 23X.

[0061] 18 shows an example in which a frame-shaped protrusion 21Y having a substantially rectangular shape is provided on the surface 21S2 of the first cladding layer 21, but the shape of the protrusion 21Y is not limited to this. For example, as shown in FIG. 19, a frame-shaped protrusion 21Y having a substantially circular shape may be provided on the surface 21S2 of the first cladding layer 21, with recesses 11X provided inside and outside the protrusion 21Y. Alternatively, as shown in FIG. 20, a frame-shaped protrusion 21Y having a polygonal shape (e.g., hexagonal shape) may be provided on the surface 21S2 of the first cladding layer 21, with recesses 11X provided inside and outside the protrusion 21Y. In either case, although not shown, a frame-shaped recess 23X that fits with the frame-shaped protrusion 21Y provided on the surface 21S2 of the first cladding layer 21 is provided on the surface 23S2 of the second cladding layer 23, and protrusions 23Y are provided inside and outside the frame-shaped recess 23X.

[0062] Even with this configuration, the same effects as those of the second embodiment can be obtained.

[0063] 5. Modification 3 FIGS. 21 to 24 schematically illustrate an example of a concave-convex structure (for example, a planar layout of the recesses 11X and protrusions 11Y of the first cladding layer 11) of a light-emitting device according to Modification 3 of the present disclosure.

[0064] In the above-described first and second embodiments and modified examples 1 and 2, examples have been shown in which the recesses 11X and 21X and the protrusions 11Y and 21Y of approximately congruent shapes are provided on the surfaces 11S2 and 21S2 of the first cladding layers 11 and 21 and the surfaces 13S1 and 23S2 of the second cladding layers 13 and 23, respectively, but the present invention is not limited to this.

[0065] 21 , for example, a substantially square frame-shaped protrusion 11Y and 3×3 substantially square protrusions 11Y in the X-axis direction and the Y-axis direction may be provided on the surface 11S2 of the first cladding layer 11. Although not shown, a substantially square frame-shaped recess 13X that fits into the substantially square frame-shaped protrusion 11Y of the first cladding layer 11 and the 3×3 substantially square protrusions 11Y in the X-axis direction and the Y-axis direction may be provided on the surface 13S2 of the second cladding layer 13.

[0066] 22 , for example, one substantially circular convex portion 11Y may be provided inside eight substantially rectangular convex portions 11Y arranged in a frame shape on the surface 11S2 of the first cladding layer 11. Although not shown, eight substantially rectangular recesses 13X and one substantially circular recess 13X are provided on the surface 13S2 of the second cladding layer 13, which fit with the eight substantially rectangular convex portions 11Y and one substantially circular convex portion 11Y of the first cladding layer 11.

[0067] 23 , for example, a plurality of annular convex portions 11Y of different widths may be provided on the surface 11S2 of the first cladding layer 11. Although not shown, a plurality of annular concave portions 13X of different widths are provided on the surface 13S2 of the second cladding layer 13 to mate with the plurality of annular convex portions 11Y of different widths of the first cladding layer 11.

[0068] 24 , for example, a polygonal (e.g., hexagonal) frame-shaped protrusion 21Y may be provided on the surface 11S2 of the first cladding layer 11, and a substantially rectangular protrusion 11Y may be provided at the center of the protrusion 21Y. Although not shown, a polygonal (e.g., hexagonal) frame-shaped recess 13X and a substantially rectangular recess 13X may be provided at the center of the surface 13S2 of the second cladding layer 13, and the frame-shaped protrusion 21Y may be provided on the surface 13S2 of the second cladding layer 13. The frame-shaped recess 13X may be fitted with the polygonal (e.g., hexagonal) frame-shaped protrusion 21Y and the substantially rectangular protrusion 11Y provided at the center of the first cladding layer 11.

[0069] In this way, two or more different patterns of recesses 11X, 21X and protrusions 11Y, 21Y may be provided on the surfaces 11S2, 21S2 of the first cladding layers 11, 21 and the surfaces 13S1, 23S2 of the second cladding layers 13, 23. Even with this configuration, the same effects as those of the first and second embodiments can be obtained.

[0070] The recesses 11X, 21X and protrusions 11Y, 21Y of two or more different patterns may be arranged randomly without any regularity in the XY plane, as shown in FIG. 25, for example.

[0071] 6. Modification 4 FIGS. 26 to 28 are schematic diagrams illustrating an example of a cross-sectional configuration of a light-emitting device (for example, light-emitting device 1A) according to Modification 4 of the present disclosure.

[0072] In the above-described first and second embodiments, examples have been shown in which the recesses 11X, 21X and the protrusions 11Y, 21Y each having a flat portion are provided on the surfaces 11S2, 21S2 of the first cladding layers 11, 21 and the surfaces 13S1, 23S2 of the second cladding layers 13, 23, respectively. However, the shapes of the recesses 11X, 21X and the protrusions 11Y, 21Y are not limited to these.

[0073] For example, as in the light-emitting device 1A shown in Figure 26, a plurality of recesses 11X and a plurality of protrusions 11Y each having an inclined surface and no flat portion may be provided on the surface 11S2 of the first cladding layer 11, and a plurality of protrusions 13Y and a plurality of recesses 13X each having an inclined surface and no flat portion may be provided on the surface 13S1 of the second cladding layer 13, which engage with the plurality of recesses 11X and a plurality of protrusions 11Y of the first cladding layer 11.

[0074] For example, as in the light-emitting device 2A shown in Figure 27, a single convex portion 21Y consisting of an inclined surface and having no flat portion may be provided approximately in the center of the surface 21S2 of the first cladding layer 21, and a single concave portion 23X consisting of an inclined surface that fits into the single convex portion 21Y of the first cladding layer 21 may be provided on the surface 23S1 of the second cladding layer 13.

[0075] Furthermore, for example, as in the light-emitting device 1B shown in Figure 28, a surface 11S2 of the first cladding layer 11 may be provided with a plurality of wavy recesses 11X and a plurality of wavy protrusions 11Y, and a surface 13S1 of the second cladding layer 13 may be provided with a plurality of wavy protrusions 13Y and a plurality of wavy recesses 13X that fit with the plurality of wavy recesses 11X and a plurality of wavy protrusions 11Y of the first cladding layer 11.

[0076] In this way, by providing the recesses 11X, 21X and the protrusions 11Y, 21Y that are made of inclined surfaces and have no flat portions, the light-emitting area in the XY plane can be increased compared to the first and second embodiments. Therefore, in addition to the effects of the first and second embodiments, it is possible to achieve even higher brightness and lower power consumption in an image display device using this.

[0077] 7. Modification 5 FIG. 29 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device (for example, a light-emitting device 1C) according to Modification 5 of the present disclosure.

[0078] In the first and second embodiments, the quantum well layers 121, 123, and 125 constituting the light-emitting layer 12 are formed continuously in the XY plane along the recesses 11X and 21X and the protrusions 11Y and 21Y provided in the first cladding layers 11 and 21, respectively. However, the quantum well layers 121, 123, and 125 may be stepped at an inclined surface between the recesses 11X and the protrusions 11Y, respectively, as shown in FIG.

[0079] 1 and 29 show examples in which the light-emitting layer 12 is formed to a substantially uniform thickness, the thickness of the light-emitting layer 12 may be different between the flat portions of the recessed portions 11X and the protruding portions 11Y and the inclined surfaces therebetween. Furthermore, the composition ratio of the compound semiconductor material constituting the light-emitting layer 12 may be different between the flat portions of the recessed portions 11X and the protruding portions 11Y and the inclined surfaces therebetween.

[0080] Even with this configuration, the same effects as those of the first and second embodiments can be obtained.

[0081] 8. Modification 6 FIG. 30 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 2B according to Modification 6 of the present disclosure.

[0082] In the second embodiment, an example was shown in which the current confinement region 211 was provided in the first cladding layer 21 and the refractive index varying region 23A composed of a plurality of grooves 23Z was provided on the surface 23S2 side of the second cladding layer 23, but this is not limited to this. In the light-emitting device 2B of this modification, a refractive index varying region composed of a plurality of grooves 21Z is provided on the surface 21S1 side of the first cladding layer 21, and a current confinement region 231 is provided in the second cladding layer 23.

[0083] Even with this configuration, the same effects as those of the second embodiment can be obtained.

[0084] 9. Modification 7 FIGS. 31 and 32 are schematic diagrams illustrating an example of a cross-sectional configuration of a light-emitting device (light-emitting devices 1D and 1E) according to Modification 7 of the present disclosure.

[0085] As in the light-emitting device 1D shown in Fig. 31 , voids G may be formed in the second cladding layer 13 above the plurality of recesses 11X provided on the surface 11S2 of the first cladding layer 11. Alternatively, as in the light-emitting device 1E shown in Fig. 32 , the voids G may be provided inside the plurality of protrusions 11Y provided on the surface 11S2 of the first cladding layer 11. By forming the voids G in one or both of the first cladding layer 11 and the second cladding layer 13, the refractive index can be controlled.

[0086] Even with this configuration, the same effects as those of the first embodiment can be obtained.

[0087] 10. Modification 8 FIG. 33 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 3A according to Modification 8 of the present disclosure.

[0088] The light-emitting device 3A includes a first cladding layer 11, a light-emitting layer 12, and a second cladding layer 13 stacked in this order, with electrodes 31 and 32 provided on a surface 11S1 of the first cladding layer 11 and a surface 13S2 of the second cladding layer 13, respectively. Furthermore, a convex lens 33, for example, is provided on the surface 13S2 of the second cladding layer 13, which serves as a light-emitting surface.

[0089] The electrode 31 is in contact with the first cladding layer 11 and is electrically connected to the first cladding layer 11. In other words, the electrode 31 is in ohmic contact with the first cladding layer 11. The electrode 31 is, for example, a metal electrode, and is configured as, for example, a multilayer film (Ni / Au) of nickel (Ni) and gold (Au). Alternatively, the electrode 31 may be formed using a transparent conductive material such as indium tin oxide (ITO).

[0090] The electrode 32 is in contact with the second cladding layer 13 and is electrically connected to the second cladding layer 13. In other words, the electrode 32 is in ohmic contact with the second cladding layer 13. The electrode 32 is formed using a transparent conductive material such as ITO.

[0091] The lens 33 corresponds to a specific example of a "light-collecting structure" in an embodiment of the present disclosure. The lens 33 may have an outer diameter that is approximately the same as the outer diameter of the light-emitting device 3A, or may be smaller than the outer diameter of the light-emitting device 3A. The lens 33 may be formed using silicon oxide or the like and separately bonded to the surface 13S2 of the second cladding layer 13. Alternatively, the lens 33 may be formed by processing the surface 13S2 of the second cladding layer 13 by etching, for example.

[0092] 11. Modification 9 FIGS. 34 and 35 are schematic diagrams illustrating an example of a cross-sectional configuration of a light-emitting device (light-emitting devices 3B and 3C) according to Modification 9 of the present disclosure.

[0093] As shown in Fig. 34, the light-emitting device 3B of this modification has a Fresnel mirror structure in which the side surfaces formed by laminating the first cladding layer 11, the light-emitting layer 12, and the second cladding layer 13 in this order are inclined. As shown in Fig. 35, the light-emitting device 3C of this modification has a side surface formed by laminating the first cladding layer 11, the light-emitting layer 12, and the second cladding layer 13 in this order as inclined, and further has a laminated film 34 including an insulating film 34A and a reflective film 34B provided on the side surface and bottom surface.

[0094] In this way, in this modification, mirror structures are provided on the side surfaces of the light-emitting devices 3B and 3C, which makes it possible to improve the light extraction efficiency in addition to the effects of the first and second embodiments.

[0095] Furthermore, as in the light-emitting device 3D shown in Fig. 36, a roughened structure may be formed on the light-emitting surface (surface 13S2) of a light-emitting device having a mirror structure on the side surface, thereby further improving the light extraction efficiency.

[0096] 12. Modification 10 The above-described light-emitting devices 1, 1A to 1E, 2, 2A to 2C, and 3A to 3C can be mounted on a display unit 1210 of a head-mounted display 1000 (described later) in the following manner.

[0097] For example, each light-emitting device including a light-emitting layer emitting a red layer (R), green light (G), and blue light (B) may be arranged in parallel in the XY plane. Alternatively, as shown in FIG. 37 , each light-emitting device 40R, 40G, and 40B emitting a red layer (R), green light (G), and blue light (B) may be stacked in the Z-axis direction for each pixel Pr, Pg, and Pb. The periphery of each light-emitting device 40R, 40G, and 40B is embedded with resin layers 41, 42, and 43 made of, for example, a light-transmitting resin material. The resin layers 41, 42, and 43 are not limited to resin materials and may be formed using, for example, an inorganic material.

[0098] 38 , when a light-emitting device 5 in which the light-emitting layer 12 is continuous across each pixel P is used, for example, as shown in Fig. 39 , a separation region 113 that electrically separates adjacent pixels P may be provided between adjacent pixels P in the second cladding layer 13. Similar to the current confinement region 211 described above, the separation region 113 can be formed by, for example, ion implantation of impurities from the surface (e.g., surface 11S1) side of the second cladding layer 13.

[0099] The position where the separation region 113 is formed is not limited to this, and it may be selectively formed at a position corresponding to the inclined surfaces of the interlocking concave-convex structure of the first cladding layer 11 and the second cladding layer 13 in each pixel P, as in the light-emitting device 5B shown in Figure 40, for example.

[0100] Alternatively, as in the light-emitting device 5C shown in Figure 41, an opening H that separates the second cladding layer 13 and the light-emitting layer 12 of adjacent pixels P may be formed, for example by dry etching, to physically separate the adjacent pixels P.

[0101] Furthermore, as in the light-emitting device 5D shown in Figure 42, a plurality of grooves 11Z that form a periodic refractive index varying region 23A as described in the second embodiment above may be provided between adjacent pixels P in the first cladding layer 11.

[0102] 43 , a separation region 111 that electrically separates adjacent pixels P may be provided between adjacent pixels P in the first cladding layer 11, and a plurality of grooves 13Z that form a periodic refractive index varying region may be provided between adjacent pixels P in the second cladding layer 13. Furthermore, a lens 33 may be disposed on a surface 13S2 of the second cladding layer 13.

[0103] Furthermore, as in the light-emitting device 5F shown in FIG. 44 , a wavelength conversion layer 35 (35R, 35G, 35B) may be provided between the surface 13S2 of the second cladding layer 13 and the lens 33. The wavelength conversion layer 35 converts the light emitted from the light-emitting layer 12 into light of a desired wavelength (e.g., red light (R), green light (G), and blue light (B)) and emits the light. This allows a full-color image display device to be realized. Note that when the light emitted from the light-emitting layer 12 is light in the blue wavelength range (blue light (B)), the wavelength conversion layer 35B provided in the blue pixel Pb may be formed, for example, using a transparent resin material having optical transparency, so that the light (blue light) emitted from the light-emitting layer 12 can be extracted as is.

[0104] 45 is a perspective view showing an example of the appearance of an image display device (head-mounted display 1000) using a light-emitting device (e.g., light-emitting device 1) according to the present disclosure. The head-mounted display 1000 has, for example, a glasses-shaped display unit 1210 and ear hooks 1220 on both sides of the glasses-shaped display unit 1210 for wearing on the user's head. The light-emitting device (e.g., light-emitting device 1) according to the present disclosure can be used for the display unit 1210.

[0105] (Application Example 2) FIG. 46 is a perspective view showing another example (head-mounted display 2000) of the appearance of an image display device using a light-emitting device (e.g., light-emitting device 1) according to the present disclosure. The head-mounted display 2000 is a so-called see-through head-mounted display and has a main body 2210, an arm 2220, and a lens barrel 2230. The head-mounted display 2000 is attached to, for example, eyeglasses 2240. The main body 2210 has a control board and a display unit for controlling the operation of the head-mounted display 2000. The display unit emits image light of a display image, and can use a light-emitting device (e.g., light-emitting device 1) according to the present disclosure. The arm 2220 connects the main body 2210 and the lens barrel 2230 and supports the lens barrel 2230. The lens barrel 2230 projects image light supplied from the main body 2210 via the arm 2220 through the lenses 2250 of the glasses 2240 toward the user's eyes.

[0106] Although the present technology has been described above by way of the embodiment, modifications 1 to 10, and application examples, the present technology is not limited to the above-described embodiment, etc., and various modifications are possible. For example, in the above-described embodiment, etc., the components constituting the light-emitting device 1 etc. are specifically described, but it is not necessary to include all of the components, and other components may also be included.

[0107] Furthermore, the above modifications 1 to 10 can be combined with each other.

[0108] The effects described in this specification are merely examples and are not limited to those described, and other effects may also be obtained.

[0109] The present technology can also be configured as follows. According to the present technology configured as follows, it is possible to improve light-emitting efficiency by suppressing diffusion of carriers in a planar direction within a light-emitting layer. (1) A light-emitting device comprising: a first compound semiconductor layer having a first surface and a second surface opposing each other and having at least one first uneven structure on the first surface; a second compound semiconductor layer having a third surface facing the first surface and a fourth surface opposite to the third surface and having a second uneven structure on the third surface that fits into the first uneven structure; and a light-emitting layer provided between the first compound semiconductor layer and the second compound semiconductor layer. (2) The light-emitting device according to (1), wherein the first compound semiconductor layer has, as the first uneven structure, a first convex portion and a first concave portion formed at both ends of the first convex portion; the second compound semiconductor layer has, as the second uneven structure, a second concave portion that fits with the first convex portion and second convex portions that are formed at both ends of the second concave portion and that fit with the first concave portion; and the thickness of the second compound semiconductor layer in the normal direction to the fourth surface increases from near the boundary between the second concave portion and the second convex portion toward the second convex portion. (3) The light-emitting device according to (1), wherein the first compound semiconductor layer has, as the first uneven structure, a first convex portion and a first concave portion formed at both ends of the first convex portion; the second compound semiconductor layer has, as the second uneven structure, a second concave portion that fits with the first convex portion and a second convex portion that is formed at both ends of the second concave portion and fits with the first concave portion; and the thickness of the second compound semiconductor layer in the normal direction to the fourth surface is thinnest at a boundary portion between the second concave portion and the second convex portion of the second compound semiconductor layer and is thickest at a boundary portion between a side surface and an upper surface of the second compound semiconductor layer that constitutes the second convex portion.(4) The light-emitting device according to (1), wherein the first compound semiconductor layer has, as the first uneven structure, first convex portions and first concave portions formed at both ends of the first convex portions, the second compound semiconductor layer has, as the second uneven structure, second concave portions that fit with the first convex portions and second convex portions that are formed at both ends of the second concave portions and that fit with the first concave portions, and the width of a bottom surface of the first concave portion is smaller than twice the thickness of the second compound semiconductor layer above the first convex portions. (5) The light-emitting device according to any one of (1) to (4), wherein the fourth surface is a light-emitting surface and forms a flat surface. (6) The light-emitting device according to any one of (1) to (4), wherein the fourth surface is a light-emitting surface and has a depression above the first concave portion that is the first uneven structure. (7) The light-emitting device according to any one of (1) to (6), wherein the light-emitting layer has a quantum well structure in which quantum well layers and barrier layers are alternately stacked, and the quantum well layer is divided between first concave portions and first convex portions as the first uneven structure. (8) The light-emitting device according to any one of (1) to (7), wherein the first compound semiconductor layer includes one or more annular concave portions in its surface as the first concave portions of the first uneven structure. (9) The light-emitting device according to (8), wherein the multiple annular concave portions are formed concentrically. (10) The light-emitting device according to any one of (1) to (7), wherein the first compound semiconductor layer includes multiple independent concave portions in its surface as the first concave portions of the first uneven structure. (11) The light-emitting device according to any one of (1) to (7), wherein the first compound semiconductor layer has a periodic concave-convex structure in its surface as the first uneven structure. (12) The light-emitting device according to any one of (1) to (11), wherein the second compound semiconductor layer has a periodic refractive index varying region on the fourth surface. (13) The light-emitting device according to any one of (1) to (12), further comprising a current confinement structure in the first compound semiconductor layer or the second compound semiconductor layer.(14) The light-emitting device according to any one of (1) to (13), wherein the second compound semiconductor layer has a void above a first concave portion as the first uneven structure. (15) The light-emitting device according to any one of (1) to (14), wherein the first uneven structure includes two or more types of uneven patterns. (16) The light-emitting device according to any one of (1) to (15), wherein the first uneven structure is formed of an inclined surface. (17) The light-emitting device according to any one of (1) to (16), further comprising a light-collecting structure on the fourth surface side of the second compound semiconductor layer. (18) The light-emitting device according to any one of (1) to (17), further comprising a mirror structure on a side surface of a stacked body consisting of the first compound semiconductor layer, the light-emitting layer, and the second compound semiconductor layer. (19) The light-emitting device according to any one of (1) to (18), wherein the pitch of the first unevenness structure is 700 nm or less. (20) An image display device comprising: a plurality of light-emitting devices for each of a plurality of pixels arranged in an array, each of the plurality of light-emitting devices comprising: a first compound semiconductor layer having a first surface and a second surface facing each other and having at least one first unevenness structure on the first surface, a second compound semiconductor layer having a third surface facing the first surface and a fourth surface opposite to the third surface and having a second unevenness structure on the third surface that fits with the first unevenness structure, and a light-emitting layer provided between the first compound semiconductor layer and the second compound semiconductor layer.

[0110] This application claims priority based on Japanese Patent Application No. 2023-219919, filed on December 26, 2023, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0111] Those skilled in the art will recognize that various modifications, combinations, subcombinations, and variations may occur depending on design requirements and other factors, and are intended to be within the scope of the appended claims and their equivalents.

Claims

1. A light-emitting device comprising: a first compound semiconductor layer having opposing first and second surfaces and at least one first concavo-convex structure on the first surface; a second compound semiconductor layer having a third surface facing the first surface and a fourth surface opposite to the third surface, and having a second concavo-convex structure on the third surface that fits with the first concavo-convex structure; and a light-emitting layer provided between the first compound semiconductor layer and the second compound semiconductor layer.

2. The first compound semiconductor layer has a first convex portion as the first concavo-convex structure and first concave portions formed at both ends of the first convex portion. The second compound semiconductor layer has a second concave portion that fits with the first convex portion as the second concavo-convex structure and second convex portions formed at both ends of the second concave portion and that fit with the first concave portions. The thickness of the second compound semiconductor layer in the normal direction of the fourth surface increases from near the boundary between the second concave portion and the second convex portion toward the second convex portion. The light-emitting device according to claim 1.

3. The first compound semiconductor layer has a first convex portion as the first concavo-convex structure and first concave portions formed at both ends of the first convex portion. The second compound semiconductor layer has a second concave portion that fits with the first convex portion as the second concavo-convex structure and second convex portions formed at both ends of the second concave portion and that fit with the first concave portions. The thickness of the second compound semiconductor layer in the normal direction of the fourth surface is the thinnest at the boundary between the second concave portion and the second convex portion of the second compound semiconductor layer and is the thickest at the boundary between the side surface and the upper surface of the second compound semiconductor layer constituting the second convex portion. The light-emitting device according to claim 1.

4. The first compound semiconductor layer has a first convex portion as the first concavo-convex structure and first concave portions formed at both ends of the first convex portion. The second compound semiconductor layer has a second concave portion that fits with the first convex portion as the second concavo-convex structure and second convex portions formed at both ends of the second concave portion and that fit with the first concave portions. The width of the bottom surface of the first concave portion is smaller than twice the thickness of the second compound semiconductor layer above the first convex portion. The light-emitting device according to claim 1.

5. The fourth surface is a light-emitting surface and forms a flat surface. The light-emitting device according to claim 1.

6. The light-emitting device according to claim 1, wherein the fourth surface is a light-emitting surface and has a depression above the first concave portion as the first concavo-convex structure.

7. The light-emitting device according to claim 1, wherein the light-emitting layer has a quantum well structure in which a quantum well layer and a barrier layer are alternately laminated, and the quantum well layer is divided between the first concave portion and the first convex portion as the first concavo-convex structure.

8. The light-emitting device according to claim 1, wherein the first compound semiconductor layer includes one or more annular concave portions in the plane as the first concave portion as the first concavo-convex structure.

9. The light-emitting device according to claim 8, wherein the plurality of annular concave portions are formed concentrically.

10. The light-emitting device according to claim 1, wherein the first compound semiconductor layer includes a plurality of concave portions independent of each other in the plane as the first concave portion as the first concavo-convex structure.

11. The light-emitting device according to claim 1, wherein the first compound semiconductor layer has a periodic concavo-convex structure in the plane as the first concavo-convex structure.

12. The light-emitting device according to claim 1, wherein the second compound semiconductor layer has a periodically refractive index fluctuation region on the fourth surface.

13. The light-emitting device according to claim 1, further having a current constriction structure in the first compound semiconductor layer or the second compound semiconductor layer.

14. The light-emitting device according to claim 1, wherein the second compound semiconductor layer has a void above the first concave portion as the first concavo-convex structure.

15. The light-emitting device according to claim 1, wherein the first concavo-convex structure includes two or more concavo-convex patterns.

16. The light-emitting device according to claim 1, wherein the first concavo-convex structure is composed of an inclined surface.

17. The light-emitting device according to claim 1, further having a light condensing structure on the fourth surface side of the second compound semiconductor layer.

18. The light-emitting device according to claim 1, further having a mirror structure on a side surface of a laminate composed of the first compound semiconductor layer, the light-emitting layer, and the second compound semiconductor layer.

19. The light-emitting device according to claim 1, wherein a pitch of the first concavo-convex structure is 700 nm or less.

20. An image display device including a plurality of light-emitting devices for each of a plurality of pixels arranged in an array, wherein each of the plurality of light-emitting devices has a first surface and a second surface facing each other, and a first compound semiconductor layer having at least one first concavo-convex structure on the first surface, a second compound semiconductor layer having a third surface facing the first surface and a fourth surface opposite to the third surface, and having a second concavo-convex structure fitting with the first concavo-convex structure on the third surface, and a light-emitting layer provided between the first compound semiconductor layer and the second compound semiconductor layer.