Light-emitting device and image display device

Abstract

A light emitting device according to one embodiment of the present disclosure is provided with: a first compound semiconductor layer which has a first surface and a second surface, the surfaces being opposite to each other; an active layer which faces the second surface of the first compound semiconductor layer; a second compound semiconductor layer which has a third surface that faces the active layer, and a fourth surface that is opposite to the third surface and serves as a light exit surface, while having one or more light collection structures on the fourth surface; and a current-narrowing structure which is provided within the first compound semiconductor layer or the second compound semiconductor layer.

Description

[Technical Field]

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

[0002] For example, Patent Document 1 discloses a light emitting device in which a concave mirror portion is provided on a first light reflecting layer provided on the side opposite to the light extraction side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 124163 Summary of the Invention

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

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

[0006] A light-emitting device according to an embodiment of the present disclosure includes a first compound semiconductor layer having a first surface and a second surface facing each other, an active layer facing the second surface of the first compound semiconductor layer, a second compound semiconductor layer having a third surface facing the active layer and a fourth surface serving as a light-emitting surface facing the third surface, the second compound semiconductor layer having one or more light-collecting structures on the fourth surface, and a current-confining structure provided within the first compound semiconductor layer or the second compound semiconductor layer. and the one or more light-collecting structures are formed by nanoantennas or Fresnel lenses formed on the fourth surface of the second compound semiconductor layer. .

[0007] An image display device according to an embodiment of the present disclosure includes a plurality of light-emitting devices for each of a plurality of pixels arranged in an array, and the plurality of light-emitting devices include the light-emitting devices according to the embodiment of the present disclosure.

[0008] In the light-emitting device and the image display device according to an embodiment of the present disclosure, a light-collecting structure is provided on the light-emitting surface of a second compound semiconductor layer, which is formed by stacking a first compound semiconductor layer, an active layer, and a second compound semiconductor layer in this order, and a current confinement structure is provided within the first compound semiconductor layer or the second compound semiconductor layer, thereby limiting the light-emitting region of the active layer and increasing the proportion of light incident on a lens disposed above the plurality of light-emitting devices and capturing light emitted from the plurality of light-emitting devices. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a configuration of a light-emitting device according to an embodiment of the present disclosure. [Figure 2] FIG. 10 is a cross-sectional view illustrating another example of the configuration of the light-emitting device according to the embodiment of the present disclosure. [Figure 3] FIG. 10 is a cross-sectional view illustrating another example of the configuration of the light-emitting device according to the embodiment of the present disclosure. [Figure 4A] 3A to 3C are cross-sectional views illustrating a method for manufacturing the light-emitting device shown in FIG. 2. [Figure 4B] FIG. 4B is a schematic cross-sectional view showing a step subsequent to FIG. 4A. [Figure 4C] FIG. 4C is a schematic cross-sectional view showing a step subsequent to FIG. 4B. [Figure 4D] FIG. 4D is a schematic cross-sectional view showing a step subsequent to FIG. 4C. [Figure 4E] FIG. 4B is a schematic cross-sectional view showing a step subsequent to FIG. 4D. [Figure 5] 3 is a cross-sectional view showing an example of the configuration of a light-emitting unit including a plurality of the light-emitting devices shown in FIG. 2. FIG. [Figure 6A] 1A and 1B are diagrams illustrating the difference in light-collecting effect depending on the light-emitting position in a typical light-emitting device. [Figure 6B] 1A and 1B are diagrams illustrating the difference in light-collecting effect depending on the light-emitting position in a typical light-emitting device. [Figure 6C] 1A and 1B are diagrams illustrating the difference in light-collecting effect depending on the light-emitting position in a typical light-emitting device. [Figure 7]10 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to Modification 1 of the present disclosure. FIG. [Figure 8] 10 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting device according to the first modification of the present disclosure. FIG. [Figure 9] 10 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to Modification 2 of the present disclosure. FIG. [Figure 10] 10 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting device according to Modification 2 of the present disclosure. FIG. [Figure 11] 10 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to Modification 3 of the present disclosure. FIG. [Figure 12] 10 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting device according to the third modification of the present disclosure. FIG. [Figure 13] FIG. 10 is a cross-sectional view illustrating an example of the configuration of a light-emitting device according to a fourth modification of the present disclosure. [Figure 14] 10 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting device according to the fourth modification of the present disclosure. FIG. [Figure 15] 10 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting device according to the fourth modification of the present disclosure. FIG. [Figure 16] 10 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to Modification 5 of the present disclosure. FIG. [Figure 17] 13 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting device according to the fifth modification of the present disclosure. FIG. [Figure 18] 13 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting device according to the fifth modification of the present disclosure. FIG. [Figure 19] 13 is a cross-sectional view schematically illustrating an example of the configuration of a light-emitting device according to a sixth modification of the present disclosure. FIG. [Figure 20] 20 is a cross-sectional view showing an example of the configuration of a light-emitting unit including a plurality of the light-emitting devices shown in FIG. 19. FIG. [Figure 21] FIG. 13 is a cross-sectional view illustrating an example of the configuration of a light-emitting device according to Modification 7 of the present disclosure. [Figure 22] FIG. 13 is a cross-sectional view illustrating another example of the configuration of the light-emitting device according to the seventh modification of the present disclosure. [Figure 23]FIG. 13 is a cross-sectional view illustrating an example of the configuration of a light-emitting unit according to Modification 8 of the present disclosure. [Figure 24] 13 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting unit according to Modification 8 of the present disclosure. FIG. [Figure 25] 13 is a cross-sectional view schematically illustrating another example of the configuration of the light-emitting unit according to Modification 8 of the present disclosure. FIG. [Figure 26] 1 is a perspective view illustrating an example of a configuration of an image display device according to Application Example 1 of the present disclosure. [Figure 27] FIG. 27 is a schematic diagram illustrating an example of a layout of the image display device shown in FIG. 26. [Figure 28] 10 is a perspective view illustrating an example of a configuration of an image display device according to Application Example 2 of the present disclosure. FIG. [Figure 29] FIG. 29 is a perspective view illustrating the configuration of the mounting board illustrated in FIG. 28. [Figure 30] FIG. 30 is a perspective view illustrating the configuration of the unit substrate illustrated in FIG. 29. [Figure 31] FIG. 10 is a diagram illustrating an example of an image display device according to Application Example 3 of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present disclosure will be described in detail below 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 aspects. Furthermore, the present disclosure is not limited to the arrangement, dimensions, dimensional ratios, etc. of each component shown in each drawing. The order of description is as follows. 1. Embodiment (Example of a light-emitting device in which a current confinement region is provided in the first cladding layer and the light-emitting surface of the second cladding layer is lens-shaped) 2. Modification 1 (Example in which multiple lenses are provided on the light exit surface of the second cladding layer) 3. Modification 2 (Example in which a mesa portion is provided in the first cladding layer) 4. Modification 3 (Example in which grooves are provided in the first cladding layer) 5. Modification 4 (Another structural example of the second electrode) 6. Modification 5 (Example of providing a mirror structure on the side of a light-emitting device) 7. Modification 6 (another example of lens shape) 8. Modification 7 (Example in which multiple active layers are provided) 9. Modification 8 (another example of the configuration of the light-emitting unit) 10. Application Example 1 (Example of Image Display Device) 11. Application Example 2 (Example of Image Display Device) 12. Application Example 3 (Example of Image Display Device)

[0011] <1. Embodiment> Fig. 1 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 1 according to an embodiment of the present disclosure. Fig. 2 is a schematic diagram illustrating another example of a cross-sectional configuration of a light-emitting device 1 according to an embodiment of the present disclosure. The light-emitting device 1 is suitable for use in, for example, a display pixel P of an image display device (e.g., image display device 100, see Fig. 26).

[0012] [Light-emitting device configuration] The light-emitting device 1 has a first cladding layer 11, an active layer 12, and a second cladding layer 13 stacked in this order. The light-emitting device 1 has a light-emitting surface facing the second cladding layer 13. The first cladding layer 11 has a pair of opposing surfaces (surfaces 11S1 and 11S2) and has a current-confining structure therein. The active layer 12 is stacked on the surface 11S2 of the first cladding layer 11. The second cladding layer 13 has a pair of opposing surfaces (surfaces 13S1 and 13S2), with the surface 13S1 facing the active layer 12. The surface 13S2 is a light-emitting surface and has a light-collecting structure (lens 13L). A first electrode 14 and a second electrode 15 are provided on the surface 11S1 of the first cladding layer 11 and the surface 13S2 of the second cladding layer 13, respectively.

[0013] The first cladding layer 11 corresponds to a specific example of a "first compound semiconductor layer" of the present disclosure and is formed of, for example, an n-type GaN-based compound semiconductor material. A current confinement structure is provided within the first cladding layer 11.

[0014] The current confinement structure has a confinement effect on current. The current confinement structure has a current injection region 11A and a current confinement region 11B. The current injection region 11A is provided, for example, approximately in the center of the first cladding layer 11 in a planar view. The current confinement region 11B is provided around the current injection region 11A. The current confinement region 11B has insulating properties and can be formed, for example, by ion implantation of impurities from the surface (e.g., surface 11S1) side of the first cladding layer 11. Alternatively, the current confinement region 11B can be formed by oxidizing the side surface of the first cladding layer 11. Furthermore, when forming the first cladding layer 11 by epitaxial crystal growth in the manufacturing process of the light-emitting device 1 described later, the current confinement region 11B can be formed by masking the current confinement region 11B portion and then growing crystals on the current injection region 11A portion. By providing the current confinement structure, the current injected from the first electrode 14 to the active layer 12 is confined, and the current injection efficiency is improved.

[0015] The current confinement structure may be formed from the first cladding layer 11 to the second cladding layer 13, as shown in FIG. 3, for example. The current injection region 11A does not necessarily have to be provided at approximately the center of the first cladding layer 11 in a plan view. For example, in a light-emitting device 1 arranged on the periphery of a display region 100A in an image display device 100 described below, the pitch of the current injection region 11A and the light-collecting structure (for example, lens 13L) may be designed to be shifted from the center of the light-emitting device 1 to change the maximum radiation angle. This makes it possible to correct in-plane variations in light-collecting efficiency caused by aberrations on the lens side that receives an image from the light-emitting device 1.

[0016] The active layer 12 emits and amplifies spontaneously emitted light, and generates stimulated emission light through luminescent recombination of holes and electrons injected from the first electrode 14 and the second electrode 15. The active layer 12 has, for example, a multiple quantum well (MQW) structure in which multiple quantum well layers (not shown) and barrier layers (not shown) are alternately stacked. The active layer 12 has a light-emitting region within the layer that corresponds to the current confinement structure.

[0017] The second cladding layer 13 corresponds to a specific example of a "second compound semiconductor layer" of the present disclosure, and is formed of, for example, a p-type GaN-based compound semiconductor material. The second cladding layer 13 has a surface 13S2 opposite to a surface 13S1 facing the active layer 12 as a light-emitting surface, and a light-collecting structure is provided on the surface 13S2. The light-collecting structure is, for example, a convex lens 13L.

[0018] The lens 13L may have a pitch (color pixel pitch) equal to or smaller than the pitch of each of the color pixels Pr, Pg, and Pb constituting the display pixel P of the image display device 100, which will be described later. Specifically, the lens 13L may have an outer diameter approximately the same as the outer diameter of the light-emitting device 1, as shown in Fig. 1, or may have an outer diameter smaller than the outer diameter of the light-emitting device 1, as shown in Fig. 2. The lens 13L is made of the same material as the second cladding layer 13, and can be formed by, for example, etching the second cladding layer 13.

[0019] The first electrode 14 is in contact with the first cladding layer 11 and is electrically connected to the first cladding layer 11. In other words, the first electrode 14 is in ohmic contact with the first cladding layer 11. The first electrode 14 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 first electrode 14 may be formed using a transparent conductive material such as indium tin oxide (ITO).

[0020] The second electrode 15 is in contact with the second cladding layer 13 and is electrically connected to the second cladding layer 13. In other words, the second electrode 15 is in ohmic contact with the second cladding layer 13. The second electrode 125 is formed using a transparent conductive material such as ITO.

[0021] [Method of manufacturing light-emitting devices] The light emitting device 1 can be manufactured, for example, as follows: Figures 4A to 4E show an example of a manufacturing process for the light emitting device 1.

[0022] 4A, the second cladding layer 13, the active layer 12, and the first cladding layer 11 are laminated in this order. The first cladding layer 11, the active layer 12, and the second cladding layer 13 can be formed by epitaxial crystal growth using a method such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE).

[0023] Next, as shown in Fig. 4B, a resist film 21 is formed in a predetermined pattern on the first cladding layer 11. Subsequently, as shown in Fig. 4C, the impurity concentration of the first cladding layer 11 exposed from the resist film 21 is controlled by, for example, ion implantation to form a current confinement region 11B. Thereafter, the resist film 21 is removed, and a first electrode 14 is formed on the first cladding layer 11.

[0024] Next, as shown in FIG. 4D, a resist film 22 having a desired lens shape is formed on the second cladding layer 13. Subsequently, as shown in FIG. 4E, the second cladding layer 13 is processed, for example, by etching, using the resist film 22 as a mask. As a result, for example, convex lenses 13L are formed on the surface of the second cladding layer 13. Thereafter, a second electrode 15 is formed on the second cladding layer 13. This completes the light-emitting device 1 shown in FIGS. 1 and 2.

[0025] [Lighting unit configuration] In an image display device 100 described below, a plurality of light-emitting devices 1 are arranged in a two-dimensional array in a display region 100A. Fig. 5 shows a schematic cross-sectional configuration of a light-emitting unit disposed for each display pixel P of the image display device 100, for example.

[0026] The light-emitting unit is, for example, a plurality of light-emitting devices 1 arranged in a line. The light-emitting unit has, for example, an elongated shape extending in the direction in which the plurality of light-emitting devices 1 are arranged. The display pixel P of the image display device 100 includes, for example, three color pixels Pr, Pg, and Pb corresponding to RGB, which are arranged at a pitch of, for example, 20 μm or less, and the light-emitting unit is mounted on the drive substrate 31 with, for example, three light-emitting devices 1 arranged in a line so that one light-emitting device 1 is arranged for each color pixel Pr, Pg, and Pb.

[0027] [Actions and Effects] In the light-emitting device 1 of this embodiment, the first cladding layer 11, the active layer 12, and the second cladding layer 13 are stacked in this order, and the light-emitting surface (surface 13S2) of the second cladding layer 13 is processed to provide a lens 13L, and a current injection region 11A and a current confinement region 11B are provided within the first cladding layer 11. This limits the light-emitting region of the active layer 12, and increases the proportion of light that enters within an acceptance angle (e.g., approximately ±10°) of the lens 13L that can focus light in a substantially frontal direction. This will be described below.

[0028] In micro-sized panel light sources (hereinafter referred to as microdisplays) used in organic electroluminescence (EL) displays and the like, lenses are used to increase the light collection efficiency in order to make effective use of the light emitted from the small light source.

[0029] Micro-sized light-emitting diodes (LEDs) have high brightness and are effective as light sources for microdisplays. However, as the LED element size decreases, the contribution of the non-emitting end face increases, significantly reducing the light extraction efficiency.

[0030] In displays with small pixel pitches, such as microdisplays, the pitch size constraints make it impossible to place lenses with large diameters, so the size of the lens and the size of the light source (LED) become close, reducing the light-collecting effect. Red LEDs in particular suffer significant deterioration in the periphery, and one way to avoid this is to increase the element size (area of ​​the active layer), but this method is difficult to use in microdisplays due to the pitch size constraints.

[0031] 6A to 6C show the light-collecting effect depending on the light-emitting position of a typical light-emitting device 1000 in which the size of the lens 1016 and the size of the light source (active layer 1012) are approximately the same as each other, as described above. In the typical light-emitting device 1000, a first electrode 1014 and a second electrode 1015 are formed between a semiconductor laminate in which a first cladding layer 1011, an active layer 1012, and a second cladding layer 1013 are laminated in this order, and a lens 1016 is disposed above the second electrode 1015, for example. In such a light-emitting device 1000, as shown in FIG. 6A, for example, light emitted at approximately the center of the active layer 1012 is efficiently extracted in the front direction by the lens 1016, but as shown in FIGS. 6B and 6C, the amount of light extracted in the front direction decreases toward the outside.

[0032] For semiconductor lasers (LDs), such as vertical-cavity surface-emitting lasers (VCSELs), device structures using lenses and current-confining structures have been proposed. However, the light emitted from the active layer of an LD is converted into coherent light by the cavity. The spread of this coherent light is related to lasing parameters such as the cavity length, and does not change even if the confinement size of the active layer is limited. For this reason, it is difficult to achieve the same effect by applying LD technology to LEDs, which emit incoherent light.

[0033] In contrast to this, in the present embodiment, the first cladding layer 11, the active layer 12, and the second cladding layer 13 are laminated in this order, and the light-emitting surface (surface 13S2) of the second cladding layer 13 is processed to provide the lens 13L. In addition, a current injection region 11A and a current confinement region 11B are provided in the first cladding layer 11, and the light-emitting region of the active layer 12 is limited to, for example, the focal point of the lens 13L and its vicinity, where the light-collection efficiency of the lens 13L is high. This increases the proportion of light incident on the acceptance angle of the lens 13L.

[0034] As a result, the light-emitting device 1 of this embodiment can improve the light extraction efficiency.

[0035] Furthermore, as described above, as the element size of an LED decreases, the rate of non-radiative recombination at the end facets increases, resulting in a significant decrease in power efficiency. In contrast, in the present embodiment, as described above, the current confinement structure is formed by providing, for example, current injection region 11A and current confinement region 11B in first cladding layer 11, thereby limiting the light-emitting region of active layer 12, thereby making it possible to improve power efficiency.

[0036] Furthermore, in this embodiment, the second cladding layer 13 is processed to provide a lens 13L on the surface 13S2 of the second cladding layer 13. This reduces the boundary reflection loss between the crystal and the lens surface and the distance between the lens and the light-emitting point, compared to when a lens is separately disposed above the light-emitting device. It also enables a reduction in the manufacturing process and a reduction in device size (miniaturization). Furthermore, by using the second cladding layer 13 itself, formed by epitaxial crystal growth, as the lens 13L, it is possible to capture light at a wide angle due to its large refractive index. This makes it possible to reduce the decrease in efficiency caused by Fresnel reflection between the lens and the LED in a typical light-emitting device (e.g., the light-emitting device 1000).

[0037] Next, modifications 1 to 8 of the present disclosure will be described. Note that components corresponding to those of the light emitting device 1 of the above embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0038] <2. Variation 1> 7 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 1A according to Modification 1 of the present disclosure. Similar to the light-emitting device 1 in the above embodiment, the light-emitting device 1A is suitable for use in, for example, a display pixel P of an image display device 100.

[0039] In the above embodiment, an example has been shown in which one lens 13L is provided on the surface 13S1 of the second cladding layer 13 in one light-emitting device 1, but this is not limiting. For example, as shown in Fig. 7, two or more lenses 13L may be provided on the surface 13S1 of the second cladding layer 13 in one light-emitting device 1A.

[0040] Furthermore, when a plurality of lenses 13L are provided, a plurality of current injection regions 11A may be provided in accordance with the number of lenses 13L, as shown in Fig. 8. This limits the light emitting region of the active layer 12 to each of the focal points of the plurality of lenses 13L and their vicinities.

[0041] In this way, in this modification, a plurality of lenses 13L are provided in one light-emitting device 1, and in addition to the effect of the above embodiment, it is possible to efficiently use the portions with good injection efficiency.

[0042] <3. Variation 2> Fig. 9 is a schematic diagram showing an example of a cross-sectional configuration of a light-emitting device 1B according to Modification 2 of the present disclosure. Fig. 10 is a schematic diagram showing another example of a cross-sectional configuration of a light-emitting device 1B according to Modification 2 of the present disclosure. Like the light-emitting device 1 in the above embodiment, the light-emitting device 1B is suitable for use in, for example, a display pixel P of an image display device 100.

[0043] 9, the current confinement structure may be formed by a mesa portion M obtained by grinding the peripheral edge of the first cladding layer 11. Alternatively, as shown in FIG. 10, a groove 11X may be provided surrounding a desired region (e.g., a substantially central portion) of the first cladding layer 11, and the first electrode 14 may be provided on a surface 11S1 of the first cladding layer 11 inside the groove 11X.

[0044] In this way, in this modification, the mesa portion M and the groove 11X are provided in the first cladding layer 11 to mechanically confine the current injected from the first electrode 14 to the active layer 12. This provides the same effect as the above embodiment.

[0045] <4. Variation 3> 11 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 1C according to Modification 3 of the present disclosure. Similar to the light-emitting device 1 in the above embodiment, the light-emitting device 1C is suitable for use in, for example, a display pixel P of an image display device 100.

[0046] In the above embodiment, an example has been shown in which the second electrode 15 is provided so as to cover the lens 13L, but the second electrode 15 may also be provided on the flat surface 13S2 of the second cladding layer 13 around the lens 13L, as shown in Fig. 11. In this case, the second electrode 15 may be formed as a metal electrode such as a multilayer film (Ti / Al) of titanium (Ti) and aluminum (Al) or a multilayer film (Cr / Au) of chromium (Cr) and gold (Au).

[0047] Furthermore, when the second electrode 15 is provided on the lens 13L as in the above embodiment, a light-reflecting film 16 may be formed on the flat surface 13S2 of the second cladding layer 13 around the lens 13L, as shown in FIG. 12. The light-reflecting film 16 is preferably formed using a material that has high reflectivity for light emitted from the active layer 12 regardless of the angle of incidence. Examples of such materials include gold (Au), silver (Ag), aluminum (Al), and platinum (Pt). Other materials that may be used include titanium (Ti), copper (Cu), nickel (Ni), or alloys thereof.

[0048] As described above, in this modification, a metal electrode is provided as the second electrode 15 on the flat surface 13S2 of the second cladding layer 13 around the lens 13L. Furthermore, when the second electrode 15 is provided on the lens 13L, a light-reflecting film 16 is formed on the flat surface 13S2 of the second cladding layer 13 around the lens 13L. This causes light incident on the surface 13S2 of the second cladding layer 13 other than the lens 13L portion to be reflected by the second electrode 15 or the light-reflecting film 16, thereby increasing the probability that the light will be incident at the acceptance angle of the lens 13L. Therefore, it is possible to further improve the light extraction efficiency compared to the above embodiment.

[0049] <5. Variation 4> 13 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 1D according to Modification 4 of the present disclosure. Similar to the light-emitting device 1 in the above embodiment, the light-emitting device 1D is suitable for use in, for example, a display pixel P of an image display device 100.

[0050] The light-emitting device 1D of this modification differs from the light-emitting device 1 of the above embodiment in that a mirror structure is provided on the side surface. Specifically, as shown in FIG. 13, for example, the side surface of the light-emitting device 1D may be an inclined surface that continues from the first cladding layer 11 to the second cladding layer 13, and the periphery may be covered with a light-reflecting film 17A. Alternatively, as shown in FIG. 14, for example, the side surface of the light-emitting device 1D may have a mirror structure. Alternatively, as shown in FIG. 15, for example, the side surface of the light-emitting device 1D may have a parabolic mirror structure. Alternatively, the side surface of the light-emitting device 1D may have a Fresnel mirror structure.

[0051] In this way, in this modification, the mirror structure is provided on the side surface of light-emitting device 1D, so that light emitted from active layer 12 that does not travel toward the light-emitting surface (surface 13S2) as shown by the arrows in Figures 13 to 15 is repeatedly reflected by the mirror structure on the side surface of light-emitting device 1D, and ultimately becomes light traveling toward the light-emitting surface (surface 13S2) and is extracted from lens 13L. Therefore, it is possible to further improve the light extraction efficiency compared to the above embodiment.

[0052] <6. Variation 5> Fig. 16 is a schematic diagram showing an example of a cross-sectional configuration of a light-emitting device 1E according to Modification 5 of the present disclosure. Fig. 17 is a schematic diagram showing another example of a cross-sectional configuration of a light-emitting device 1E according to Modification 5 of the present disclosure. Fig. 18 is a schematic diagram showing another example of a cross-sectional configuration of a light-emitting device 1E according to Modification 5 of the present disclosure. Like the light-emitting device 1 in the above embodiment, the light-emitting device 1E is suitably used for, for example, a display pixel P of an image display device 100.

[0053] In the above embodiment, an example was shown in which a convex lens 13L was formed on the surface 13L2 of the second cladding layer 13 as the light-collecting structure, but the shape of the lens 13L is not limited to this. For example, as shown in Fig. 16, a portion of the surface of the lens 13L may be flat. Alternatively, the light-collecting structure may be formed of a nanoantenna 13LA, for example, as shown in Fig. 17, or a Fresnel lens 13LB, for example, as shown in Fig. 18, and the same effects as those of the above embodiment can be obtained.

[0054] <7. Variation 6> 19 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 1F according to Modification 6 of the present disclosure. Similar to the light-emitting device 1 in the above embodiment, the light-emitting device 1F is suitable for use in, for example, a display pixel P of an image display device 100.

[0055] The active layer 12 may be made up of a plurality of layers 12R, 12G, and 12B that emit light corresponding to RGB (red light Lr, green light Lg, and blue light Lb), for example, as shown in FIG.

[0056] Fig. 20 is a schematic diagram showing the cross-sectional configuration of a light-emitting unit using the light-emitting device 1F shown in Fig. 19. The light-emitting unit shown in Fig. 20 has light-emitting devices 1Fr, 1Fg, and 1Fb corresponding to RGB arranged in a row.

[0057] In the light-emitting device 1F, for example, a layer 12B emitting blue light Lb, a layer 12G emitting green light Lg, and a layer 12R emitting red light Lr are stacked in this order, and a compound semiconductor layer having a configuration similar to that of the first cladding layer 11 is provided between the layers 12B, 12G, and 12R. In the light-emitting unit shown in FIG. 20, the light-emitting devices 1Fr, 1Fg, and 1Fb disposed in the color pixels Pr, Pg, and Pb, respectively, have continuous semiconductor layers. More specifically, the color pixel Pb is provided with a light-emitting device 1Fb composed of the first cladding layer 11, an active layer 12 including layers 12B, 12G, and 12R, and a second cladding layer 13. The light-emitting device 1Fb is mounted on a drive substrate 31 via a first electrode 14. In the color pixel Pg, the first cladding layer 11 and the layer 12B are removed, and a light-emitting device 1Fg is disposed in which the compound semiconductor layer between the layers 12B and 12G also serves as the first cladding layer 11. The light-emitting device 1Fg is mounted on a driving substrate 31 via a first electrode 14, a bump 32, and a pad electrode 33. In the color pixel Pr, the layers 12B and 12G are removed, and a light-emitting device 1Fr is disposed in which the compound semiconductor layer between the layers 12G and 12R also serves as the first cladding layer 11. The light-emitting device 1Fr is mounted on the driving substrate 31 via a first electrode 14, a bump 34, and a pad electrode 35. In the light-emitting unit shown in FIG. 20 , the layer 12R and the second cladding layer 13 are formed as a common layer across the light-emitting devices 1Fr, 1Fg, and 1Fb.

[0058] When a light-emitting device in which multiple layers 12R, 12G, and 12B corresponding to RGB are stacked is disposed in each color pixel Pr, Pg, and Pb, it is preferable that the lens 13L provided on the surface 13S2 of the second compound semiconductor layer has a shape having a focal point at the position of each layer 12R, 12G, and 12B, as shown in FIG.

[0059] 20 shows an example in which light-emitting device 1Fr, light-emitting device 1Fg, and light-emitting device 1Fb are arranged in a row in this order, but the respective positions of light-emitting device 1Fr, light-emitting device 1Fg, and light-emitting device 1F in the light-emitting unit are not limited to this. Furthermore, while FIG. 20 shows an example in which light-emitting devices 1Fg and 1Fr are mounted on a mounting substrate via bumps 32 and 34 and pad electrodes 33 and 35, respectively, other bonding methods such as Cu-Cu bonding may be used for mounting on drive substrate 31.

[0060] <8. Variation 7> 21 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting device 1G according to Modification 7 of the present disclosure. Similar to the light-emitting device 1 in the above embodiment, the light-emitting device 1G is suitable for use in, for example, a display pixel P of an image display device 100.

[0061] In the above embodiment, for example, an example has been shown in which light is extracted from the second cladding layer 13 side formed of a p-type GaN-based compound semiconductor material, but the present invention is not limited to this. For example, as shown in Fig. 21, a lens 11L may be provided on the surface 11S1 of the first cladding layer 11 formed of an n-type GaN-based compound semiconductor material, so that light is extracted from the first cladding layer 11 side.

[0062] Furthermore, the current confinement structure may be provided on the light emitting surface (surface 11S1) side, as shown in Fig. 21. In this modification, the second cladding layer 13 corresponds to the "first compound semiconductor layer" of the present disclosure, and the first cladding layer 11 corresponds to the "second compound semiconductor layer" of the present disclosure.

[0063] 22, a concave mirror structure 13LX may be provided on the side opposite to the light emitting surface (surface 11S1), for example, on the surface 13S2 of the second cladding layer 13. This makes it possible to efficiently reflect light traveling in the direction opposite to the light emitting surface (surface 11S1) side toward the light emitting surface (surface 11S1).

[0064] <9. Variation 8> 23 is a schematic diagram illustrating an example of a cross-sectional configuration of a light-emitting unit according to Modification 7 of the present disclosure. In the above embodiment, three light-emitting devices 1, each separated from the other, are mounted on a driving substrate 31 to form a light-emitting unit. However, the first cladding layer 11, the active layer 12, and the second cladding layer 13 constituting these three light-emitting devices may be continuous with each other as a common layer for the three light-emitting devices. This reduces the occurrence of non-light-emitting edges due to Ferro-Peripheral degradation.

[0065] 23, when the first cladding layer 11, the active layer 12, and the second cladding layer 13 are used as common layers for a plurality of light-emitting devices, an isolation region 18 may be provided to electrically or optically isolate adjacent light-emitting devices, as shown in, for example, Fig. 24. The isolation region 18 may be formed by implanting, for example, hydrogen or boron from the second cladding layer 13 side. Alternatively, as shown in, for example, Fig. 25, grooves 11X and 13X may be provided in the first cladding layer 11 and the second cladding layer 13, respectively, leaving the active layer 12, to electrically isolate the light-emitting devices from each other.

[0066] <10. Application Example 1> 26 is a perspective view showing an example of a schematic configuration of an image display device (image display device 100). The image display device 100 uses a light-emitting device according to the present disclosure (e.g., light-emitting device 1) in a display pixel P. The image display device 100 includes, for example, a display panel 110 and a control circuit 140 that drives the display panel 110, as shown in FIG.

[0067] The display panel 110 is formed by overlapping a mounting substrate 120 and a transparent substrate 130. The surface of the transparent substrate 130 serves as an image display surface, with a display area 100A in the center and a frame area 100B, which is a non-display area, surrounding the display area 100A.

[0068] 27 shows an example of a wiring layout in a region corresponding to the display region 100A on the surface of the mounting substrate 120 facing the transparent substrate 130. In the region corresponding to the display region 100A on the surface of the mounting substrate 120, for example, as shown in FIG. 27, a plurality of data wirings 1021 are formed extending in a predetermined direction and arranged in parallel at a predetermined pitch. In the region corresponding to the display region 100A on the surface of the mounting substrate 120, a plurality of scan wirings 1022 are further formed extending in a direction intersecting (for example, perpendicular to) the data wirings 1021 and arranged in parallel at a predetermined pitch. The data wirings 1021 and the scan wirings 1022 are made of a conductive material such as Cu.

[0069] The scan lines 1022 are formed, for example, in the outermost layer, for example, on an insulating layer (not shown) formed on the surface of a substrate. The substrate of the mounting board 120 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 lines 1021 are formed in a layer different from the outermost layer including the scan lines 1022 (for example, a layer below the outermost layer), for example, in an insulating layer on the substrate.

[0070] The vicinity of the intersection of the data wiring 1021 and the scan wiring 1022 is a display pixel P, and a plurality of display pixels P are arranged in, for example, a matrix within the display area 100A. Each display pixel P has color pixels Pr, Pg, and Pb corresponding to, for example, RGB, and each color pixel Pr, Pg, and Pb is respectively equipped with a corresponding light-emitting device 1R, 1G, and 1B. Figure 27 illustrates an example in which one display pixel P is configured with three light-emitting devices 1R, 1G, and 1B, and red light can be output from the light-emitting device 1R, green light can be output from the light-emitting device 1G, and blue light can be output from the light-emitting device 1B.

[0071] The light-emitting device 1 is provided with a pair of terminal electrodes, for example, one for each of the color pixels Pr, Pg, and Pb, or one common and the other for each of the color pixels Pr, Pg, and Pb. One of the terminal electrodes is electrically connected to a data line 1021, and the other is electrically connected to a scan line 1022. For example, one of the terminal electrodes is electrically connected to a pad electrode 1021B at the tip of a branch 1021A provided on the data line 1021. Furthermore, for example, the other terminal electrode is electrically connected to a pad electrode 1022B at the tip of a branch 1022A provided on the scan line 1022.

[0072] The pad electrodes 1021B and 1022B are formed, for example, on the outermost layer and are provided in a portion where the light emitting device 1 is mounted, as shown in Fig. 27. Here, the pad electrodes 121B and 122B are made of a conductive material such as Au (gold).

[0073] The mounting substrate 120 is further provided with, for example, a plurality of support columns (not shown) that regulate the distance between the mounting substrate 120 and the transparent substrate 130. The support columns may be provided in the region facing the display region 100A, or in the region facing the frame region 100B.

[0074] The transparent substrate 130 is made of, for example, a glass substrate or a resin substrate. The surface of the transparent substrate 130 facing the light-emitting device 1 may be flat, but is preferably roughened. The roughened surface may be provided over the entire area facing the display area 100A, or only in the area facing the display pixels P. The roughened surface has fine irregularities that allow the light emitted from the color pixels Pr, Pg, and Pb to enter the roughened surface. The irregularities on the roughened surface can be created by, for example, sandblasting or dry etching.

[0075] The control circuit 140 drives each display pixel P (each light-emitting device 1) based on a video signal. The control circuit 140 is configured, for example, with a data driver that drives data wiring 1021 connected to the display pixel P and a scan driver that drives scan wiring 1022 connected to the display pixel P. For example, as shown in FIG. 26 , the control circuit 140 may be provided separately from the display panel 110 and connected to the mounting substrate 120 via wiring, or may be mounted on the mounting substrate 120.

[0076] The image display device 100 shown in Fig. 26 is an example of a passive matrix image display device. The light emitting device 1 of this embodiment is not limited to passive matrix image display devices (image display devices 100) but can also be applied to active matrix image display devices. In an active matrix image display device, for example, the frame region 100B shown in Fig. 26 is not necessary.

[0077] <11. Application Example 2> 28 is a perspective view showing another example configuration of an image display device (image display device 200) using a light-emitting device (e.g., light-emitting device 1) according to the present disclosure. The image display device 200 is a so-called tiling display. As shown in FIG. 28, the image display device 200 includes, for example, a display panel 210 and a control circuit 240 that drives the display panel 210.

[0078] The display panel 210 is formed by stacking a mounting substrate 220 and a counter substrate 230 on top of each other. The surface of the counter substrate 230 serves as an image display surface, with a display area in the center and a frame area, which is a non-display area, around it (neither is shown). The counter substrate 230 is disposed in a position opposite the mounting substrate 220, for example, with a predetermined gap therebetween. The counter substrate 230 may also be in contact with the upper surface of the mounting substrate 220.

[0079] Fig. 29 is a schematic diagram showing an example of the configuration of the mounting board 220. For example, as shown in Fig. 29, the mounting board 220 is made up of a plurality of unit boards 250 laid out in a tiled pattern. Note that Fig. 29 shows an example in which the mounting board 220 is made up of nine unit boards 250, but the number of unit boards 250 may be ten or more, or eight or less.

[0080] FIG. 30 shows an example of the configuration of a unit substrate 250. The unit substrate 250 has, for example, a plurality of light-emitting devices 1 arranged in a tiled pattern and a support substrate 260 that supports each of the light-emitting devices 1. Each unit substrate 250 also has a control substrate (not shown). The support substrate 260 is made of, for example, a metal frame (metal plate) or a wiring substrate. If the support substrate 260 is made of a wiring substrate, it can also serve as the control substrate. In this case, at least one of the support substrate 260 and the control substrate is electrically connected to each of the light-emitting devices 1.

[0081] <12. Application Example 3> 31 shows the appearance of a transparent display 300. The transparent display 300 has, for example, a display unit 310, an operation unit 311, and a housing 312. The display unit 310 uses a light-emitting device (for example, the light-emitting device 1) of the present disclosure. The transparent display 300 can display images and text information while allowing the background of the display unit 310 to be seen through.

[0082] In the transparent display 300, a light-transmitting substrate is used as the mounting substrate. Each electrode provided on the light-emitting device 1 is formed using a light-transmitting conductive material, similar to the mounting substrate. Alternatively, each electrode is structured to be less visible by increasing the wiring width or reducing the wiring thickness. In addition, the transparent display 300 can display black by, for example, overlaying a liquid crystal layer equipped with a drive circuit, and switching between transparent and black display is possible by controlling the light distribution direction of the liquid crystal.

[0083] Although the present disclosure has been described above by way of the embodiment, modifications 1 to 8, and application examples, the present disclosure is not limited to the above-described embodiment, etc., and various modifications are possible. For example, two or more of the modifications 1 to 8 may be combined.

[0084] In addition, while the above-described embodiments and the like have illustrated light-emitting units that emit light corresponding to RGB, the configuration of the light-emitting units is not limited thereto. For example, the light-emitting units may be configured to emit light of two colors, such as RG and RB. Alternatively, the light-emitting units may be configured to emit light of four or more colors, such as RGBW. Furthermore, while FIG. 20 illustrates a light-emitting unit in which a display pixel P including color pixels Pr, Pg, and Pb is used as one unit, the configuration of the light-emitting units is not limited thereto. For example, the light-emitting units may be configured such that the entire display area 100A of the image display device 100 is used as one unit. In this case, the light-emitting devices 1Fr, 1Fg, and 1Fb corresponding to the color pixels Pr, Pg, and Pb are regularly arranged in a mosaic pattern on the drive substrate 31.

[0085] The effects described in this specification are merely examples and are not limited to those described, and other effects may also be obtained.

[0086] This technology can also be configured as follows. According to this technology configured as follows, a light-collecting structure is provided on the light-emitting surface of a second compound semiconductor layer, which is stacked in order of a first compound semiconductor layer, an active layer, and a second compound semiconductor layer, and a current-confining structure is provided within the first compound semiconductor layer or the second compound semiconductor layer. This limits the light-emitting region of the active layer and increases the proportion of light that enters the lens's acceptance angle. This makes it possible to improve the light extraction efficiency. (1) a first compound semiconductor layer having a first surface and a second surface opposite to each other; an active layer facing the second surface of the first compound semiconductor layer; a second compound semiconductor layer having a third surface facing the active layer and a fourth surface facing the third surface and serving as a light emitting surface, the second compound semiconductor layer having one or more light collecting structures on the fourth surface; a current confinement structure provided in the first compound semiconductor layer or the second compound semiconductor layer; Equipped with The one or more light-collecting structures are formed by a nanoantenna or a Fresnel lens formed on the fourth surface of the second compound semiconductor layer. A light-emitting device comprising: (2) The light-emitting device according to (1), wherein the current confinement structure has a current injection region and a current confinement region provided around the current injection region. (3) The light-emitting device according to (1) or (2), wherein the current confinement structure is formed from the first compound semiconductor layer to the second compound semiconductor layer or from the second compound semiconductor layer to the first compound semiconductor layer. (4) The light-emitting device described in (1) or (2), wherein the current confinement structure is formed by a groove provided in at least one of the first surface of the first compound semiconductor layer and the fourth surface of the second compound semiconductor layer. (5) The light-emitting device according to (2) or (3), wherein the current confinement region of the current confinement structure is constituted by an impurity region provided in the first compound semiconductor layer or the second compound semiconductor layer. (6) The light-emitting device according to (2) or (3), wherein the current confinement region of the current confinement structure is formed by an oxide layer provided in the first compound semiconductor layer or the second compound semiconductor layer. (7) a plurality of light-emitting regions within the active layer; The light-emitting device according to any one of (1) to (6), wherein the one or more light-collecting structures are provided on each of the fourth surfaces corresponding to the plurality of light-emitting regions. (8) The light-emitting device according to (7), wherein the active layer electrically or mechanically separates the adjacent light-emitting regions. (9 ) beforea first electrode electrically connected to the first compound semiconductor layer and a second electrode electrically connected to the second compound semiconductor layer; the second electrode is laminated to the one or more light-collecting structures; Any one of the above (1) to (8) The light-emitting device according to claim 1. (10) a light-reflecting film is laminated on the fourth surface around the one or more light-collecting structures; (9) The light-emitting device according to claim 1. (11) a first electrode electrically connected to the first compound semiconductor layer and a second electrode electrically connected to the second compound semiconductor layer; the second electrode is disposed around the one or more light-collecting structures; Any one of the above (1) to (8) The light-emitting device according to claim 1. (12) the first compound semiconductor layer has a mesa shape as the current confinement structure; Any one of the above (1) to (11) The light-emitting device according to claim 1. (13) the first compound semiconductor layer has a concave mirror structure on the first surface; Any one of the above (1) to (12) The light-emitting device according to claim 1. (14) side surfaces of the first compound semiconductor layer, the active layer, and the second compound semiconductor layer have a continuous mirror structure; Any one of the above (1) to (13) The light-emitting device according to claim 1. (15) The mirror structure is composed of a light reflecting film, a Fresnel mirror, or a parabolic mirror. (14) The light-emitting device according to claim 1. (16) The active layer is made up of a plurality of layers that emit light in different wavelength bands. Any one of the above (1) to (15) The light-emitting device according to claim 1. (17) 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 comprises: a first compound semiconductor layer having a first surface and a second surface opposite to each other; an active layer facing the second surface of the first compound semiconductor layer; a second compound semiconductor layer having a third surface facing the active layer and a fourth surface facing the third surface and serving as a light emitting surface, the second compound semiconductor layer having one or more light collecting structures on the fourth surface; a current confinement structure provided in the first compound semiconductor layer or the second compound semiconductor layer; and The one or more light-collecting structures are formed by a nanoantenna or a Fresnel lens formed on the fourth surface of the second compound semiconductor layer. An image display device having the above configuration. (18) The pitch of the plurality of pixels is 20 μm or less. (17) The image display device according to claim 1. (19) a pitch of the plurality of light-collecting structures is equal to or less than a pitch of the plurality of pixels; (17) or (18) above The image display device according to claim 1.

[0087] This application claims priority based on Japanese Patent Application No. 2021-140413, filed on August 30, 2021, with the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0088] 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 first compound semiconductor layer having a first surface and a second surface opposite to each other; an active layer facing the second surface of the first compound semiconductor layer; a second compound semiconductor layer having a third surface facing the active layer and a fourth surface facing the third surface and serving as a light emitting surface, the second compound semiconductor layer having one or more light collecting structures on the fourth surface; a current confinement structure provided in the first compound semiconductor layer or the second compound semiconductor layer, The one or more light-collecting structures are formed by a nanoantenna or a Fresnel lens formed on the fourth surface of the second compound semiconductor layer. Light-emitting device.

2. The light-emitting device according to claim 1 , wherein the current confinement structure comprises a current injection region and a current confinement region provided around the current injection region.

3. 2. The light-emitting device according to claim 1, wherein the current confinement structure is formed from the first compound semiconductor layer to the second compound semiconductor layer or from the second compound semiconductor layer to the first compound semiconductor layer.

4. 2. The light-emitting device according to claim 1, wherein the current confinement structure is formed by a groove provided in at least one of the first surface of the first compound semiconductor layer and the fourth surface of the second compound semiconductor layer.

5. 3. The light-emitting device according to claim 2, wherein the current confinement region of the current confinement structure is formed by an impurity region provided in the first compound semiconductor layer or the second compound semiconductor layer.

6. 3. The light-emitting device according to claim 2, wherein the current confinement region of the current confinement structure is formed by an oxide layer provided in the first compound semiconductor layer or the second compound semiconductor layer.

7. a plurality of light-emitting regions within the active layer; The light-emitting device according to claim 1 , wherein the one or more light-collecting structures are provided on each of the fourth surfaces corresponding to the plurality of light-emitting regions.

8. The light-emitting device according to claim 7 , wherein the active layer electrically or mechanically separates the adjacent light-emitting regions.

9. a first electrode electrically connected to the first compound semiconductor layer and a second electrode electrically connected to the second compound semiconductor layer; The light-emitting device of claim 1 , wherein the second electrode is laminated to the one or more light-collecting structures.

10. The light-emitting device according to claim 9 , wherein the fourth surface around the one or more light-collecting structures is laminated with a light-reflecting film.

11. a first electrode electrically connected to the first compound semiconductor layer and a second electrode electrically connected to the second compound semiconductor layer; The light-emitting device of claim 1 , wherein the second electrode is disposed around the one or more light-collecting structures.

12. The light-emitting device according to claim 1 , wherein the first compound semiconductor layer has a mesa shape as the current confinement structure.

13. The light-emitting device of claim 1 , wherein the first compound semiconductor layer has a concave mirror structure on the first surface.

14. The light-emitting device according to claim 1 , wherein the side surfaces of the first compound semiconductor layer, the active layer, and the second compound semiconductor layer have a continuous mirror structure.

15. The light-emitting device according to claim 14, wherein the mirror structure is formed by a light-reflecting film, a Fresnel mirror, or a parabolic mirror.

16. 2. The light-emitting device according to claim 1, wherein the active layer is made up of a plurality of layers that emit light in different wavelength bands.

17. 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 comprises: a first compound semiconductor layer having a first surface and a second surface opposite to each other; an active layer facing the second surface of the first compound semiconductor layer; a second compound semiconductor layer having a third surface facing the active layer and a fourth surface facing the third surface and serving as a light emitting surface, the second compound semiconductor layer having one or more light collecting structures on the fourth surface; a current confinement structure provided in the first compound semiconductor layer or the second compound semiconductor layer; The one or more light-collecting structures are formed by a nanoantenna or a Fresnel lens formed on the fourth surface of the second compound semiconductor layer. Image display device.

18. 18. The image display device according to claim 17, wherein the pitch of the plurality of pixels is 20 [mu]m or less.

19. The image display device according to claim 17 , wherein the pitch of the plurality of light-collecting structures is equal to or smaller than the pitch of the plurality of pixels.

Images