Light-emitting device and preparation method thereof

Abstract

A light-emitting device and a method for preparing the same. The method comprises: providing an epitaxial substrate (1), the epitaxial substrate (1) having a first recessed portion (101), the inner surface of the first recessed portion (101) being a curved surface; epitaxially growing a light-emitting structure layer (2) on the epitaxial substrate (1), the light-emitting structure layer (2) comprising a first surface (204) and a second surface (205) opposite to each other, the second surface (205) being convex toward the first recessed portion (101); forming a first reflector layer (3) on the first surface (204); and removing the epitaxial substrate (1) to form a second reflector layer (8) covering the second surface (205). This method can form a curved resonant cavity.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a light-emitting device and a method for preparing the light-emitting device. Background Art

[0002] In recent years, semiconductor light-emitting devices, as a new generation of green light sources, have been widely used in lighting, backlighting, display, indication and other fields.

[0003] To improve the performance of semiconductor light-emitting devices, a resonant cavity is often formed within them. The basic structure of a semiconductor light-emitting device with such a resonant cavity includes a first reflector layer, a second reflector layer, and a light-emitting structure layer. The light-emitting structure layer is located between the first and second reflector layers. However, engineers have been unable to create a curved resonant cavity in actual products. Summary of the Invention

[0004] The purpose of the present disclosure is to provide a light-emitting device and a method for preparing the light-emitting device, which can form a curved resonant cavity.

[0005] According to one aspect of the present disclosure, there is provided a method for preparing a light-emitting device, comprising:

[0006] Providing an epitaxial substrate, wherein the epitaxial substrate has a first recessed portion, and an inner surface of the first recessed portion is a curved surface;

[0007] epitaxially growing a light emitting structure layer on the epitaxial substrate, wherein the light emitting structure layer includes a first surface and a second surface opposite to each other, and the second surface is convex toward the first recessed portion;

[0008] forming a first reflector layer on the first surface;

[0009] The epitaxial substrate is removed to form a second reflector layer covering the second surface.

[0010] Furthermore, the epitaxial base includes a substrate, and the first recessed portion is formed in the substrate.

[0011] Furthermore, the epitaxial base includes a substrate and a nucleation layer from bottom to top, the first recessed portion is formed in the substrate, and the nucleation layer is conformally formed on the substrate.

[0012] Furthermore, the epitaxial base includes, from bottom to top, a substrate, a dielectric layer, and a nucleation layer; the first recessed portion is formed in the dielectric layer; and the nucleation layer is conformally formed on the dielectric layer.

[0013] Furthermore, there are multiple first recessed portions.

[0014] Furthermore, the light emitting structure layer further includes a side wall connecting the first surface and the second surface, and forming a second reflector layer covering the second surface includes:

[0015] A second reflector layer is formed to cover the sidewalls of the light emitting structure layer and the second surface.

[0016] Furthermore, the reflectivity of the second reflector layer is 50%-80%.

[0017] Furthermore, the second reflector layer is made of insulating material.

[0018] Furthermore, the light emitting structure layer includes an active layer, and the active layer includes, from top to bottom, a first conductive type semiconductor layer, a light emitting layer, and a second conductive type semiconductor layer. The preparation method further includes:

[0019] forming a first electrode electrically connected to the first conductive type semiconductor layer;

[0020] A second electrode electrically connected to the second conductive type semiconductor layer is formed.

[0021] Furthermore, the first electrode and the second electrode are located on both sides of the light emitting structure layer.

[0022] Furthermore, the first electrode and the second electrode are both located on a side of the first conductive type semiconductor layer away from the first reflector layer.

[0023] Furthermore, the light emitting structure layer includes an active layer and an oxide layer stacked together, the oxide layer includes a low resistance region and a high resistance region surrounding the low resistance region, and the resistance of the low resistance region is smaller than that of the high resistance region.

[0024] According to one aspect of the present disclosure, a light-emitting device is provided. The light-emitting device is manufactured by the above-mentioned method for manufacturing a light-emitting device.

[0025] In the light-emitting device and the method for preparing the light-emitting device disclosed herein, the epitaxial substrate has a first recessed portion, and the inner surface of the first recessed portion is a curved surface, so that the second surface of the light-emitting structure layer grown on the epitaxial substrate protrudes toward the first recessed portion, and then the second reflector layer covering the second surface protrudes outward to form a curved resonant cavity, thereby increasing the cavity of the resonant cavity, enhancing light confinement, and improving the photoelectric performance of the light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flow chart of a method for preparing a light-emitting device according to a first embodiment of the present disclosure;

[0027] Figure 2 is a schematic diagram of an epitaxial substrate in the first embodiment of the present disclosure;

[0028] Figure 3 is a schematic diagram after forming a support layer in the first embodiment of the present disclosure;

[0029] Figure 4 is a schematic diagram of the light-emitting structure layer after patterning in the first embodiment of the present disclosure;

[0030] Figure 5 is another schematic diagram of the light emitting structure layer after patterning in the first embodiment of the present disclosure;

[0031] Figure 6 is a schematic diagram of a light emitting device according to a first embodiment of the present disclosure;

[0032] Figure 7 is a schematic diagram of an epitaxial substrate in the second embodiment of the present disclosure;

[0033] Figure 8 is a schematic diagram of the epitaxial substrate in the third embodiment of the present disclosure;

[0034] Figure 9 is a schematic diagram of a light-emitting device according to a fourth embodiment of the present disclosure;

[0035] Figure 10 is a schematic diagram of a light-emitting device according to a fifth embodiment of the present disclosure;

[0036] Figure 11 is a schematic diagram of a light-emitting device according to a sixth embodiment of the present disclosure;

[0037] Figure 12 is a schematic diagram of a light-emitting device according to a seventh embodiment of the present disclosure;

[0038] Figure 13 This is another schematic diagram of the light-emitting device of the seventh embodiment of the present disclosure.

[0039] Explanation of the accompanying drawings: 1. Epitaxial base; 101. First recessed portion; 102. Substrate; 103. Nucleation layer; 104. Dielectric layer; 2. Light-emitting structure layer; 20. Active layer; 201. First conductive type semiconductor layer; 202. Light-emitting layer; 203. Second conductive type semiconductor layer; 204. First surface; 205. Second surface; 21. Oxide layer; 211. Low resistance region; 212. High resistance region; 3. First reflector layer; 4. ITO layer; 5. Support layer; 501. Heavily doped silicon substrate; 502. Metal bonding layer; 6. Metal protective layer; 7. Isolation trench; 8. Second reflector layer; 9. First electrode; 10. Second electrode. DETAILED DESCRIPTION

[0040] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present disclosure. Rather, they are merely examples of devices consistent with certain aspects of the present disclosure, as detailed in the appended claims.

[0041] Example 1

[0042] Figure 1 This is a flow chart of a method for preparing a light-emitting device according to the first embodiment of the present disclosure. Figure 2 It is a schematic diagram of the epitaxial substrate in the first embodiment of the present disclosure. Figure 3 It is a schematic diagram after the support layer is formed in the first embodiment of the present disclosure. Figure 4 It is a schematic diagram of the light-emitting structure layer after patterning in the first embodiment of the present disclosure. Figure 5 This is another schematic diagram of the light-emitting structure layer after patterning in the first embodiment of the present disclosure. Figure 6 Schematic diagram of the light-emitting device according to the first embodiment of the present disclosure.

[0043] like Figure 1 As shown, the method for preparing the light-emitting device according to the first embodiment of the present disclosure may include steps S100 to S130:

[0044] Step S100 : providing an epitaxial substrate, wherein the epitaxial substrate has a first recessed portion, and an inner surface of the first recessed portion is a curved surface.

[0045] Step S110 , epitaxially growing a light emitting structure layer on the epitaxial substrate, wherein the light emitting structure layer includes a first surface and a second surface opposite to each other, and the second surface is convex toward the first recessed portion.

[0046] Step S120 , forming a first reflector layer on the first surface.

[0047] Step S130 , removing the epitaxial substrate to form a second reflector layer covering the second surface.

[0048] In the method for preparing the light-emitting device of the first embodiment of the present disclosure, the epitaxial substrate has a first recessed portion, and the inner surface of the first recessed portion is a curved surface, so that the second surface of the light-emitting structure layer grown on the epitaxial substrate protrudes toward the first recessed portion, and then the second reflector layer covering the second surface protrudes outward to form a curved resonant cavity, thereby increasing the cavity of the resonant cavity, enhancing light confinement, and improving the photoelectric performance of the light-emitting device.

[0049] The following is a detailed description of each step of the method for preparing the light-emitting device according to the first embodiment of the present disclosure:

[0050] In step S100 , an epitaxial substrate is provided. The epitaxial substrate has a first recessed portion, and the inner surface of the first recessed portion is a curved surface.

[0051] like Figure 2 As shown, the first recessed portion 101 can be flared, that is, the cross-sectional area of ​​the first recessed portion 101 in a direction parallel to the epitaxial substrate 1 gradually increases from the bottom to the top of the first recessed portion 101. The number of the first recessed portions 101 can be one, two, three, or more. Taking the example of a plurality of first recessed portions 101, the plurality of recessed portions can be located on the same surface of the epitaxial substrate 1, and the plurality of first recessed portions 101 can be spaced apart. In this embodiment, the epitaxial substrate 1 can include a substrate 102, and the first recessed portion 101 can be formed in the substrate 102. The substrate 102 can be a silicon substrate, or of course, a silicon carbide substrate, but is not limited thereto, and can also be a sapphire substrate.

[0052] In step S110 , a light emitting structure layer is epitaxially grown on the epitaxial substrate. The light emitting structure layer includes a first surface and a second surface opposite to each other. The second surface is convex toward the first recessed portion.

[0053] like Figure 3 As shown, the light-emitting structure layer 2 can be grown on the side of the substrate 102 having the recess. The light-emitting structure layer 2 includes an active layer 20. The active layer 20 may include, from top to bottom, a first conductivity-type semiconductor layer 201, a light-emitting layer 202, and a second conductivity-type semiconductor layer 203. For example, epitaxially growing the light-emitting structure layer 2 on the epitaxial substrate 1 may include sequentially epitaxially growing the second conductivity-type semiconductor layer 203, the light-emitting layer 202, and the first conductivity-type semiconductor layer 201 on the epitaxial substrate 1. The light-emitting layer 202 may have at least one of a single quantum well structure, a multiple quantum well (MQW) structure, a quantum wire structure, and a quantum dot structure. For example, if the light-emitting layer 202 is a multiple quantum well structure, the light-emitting layer 202 includes alternating well layers and barrier layers. The first conductivity type is different from the second conductivity type. The first conductivity-type semiconductor layer 201 may be a P-type semiconductor layer, and the second conductivity-type semiconductor layer 203 may be an N-type semiconductor layer, but this is not specifically limited in this disclosure. The first surface 204 of the light-emitting structure layer 2 can be the surface of the first conductive type semiconductor layer 201 facing away from the light-emitting layer 202. The second surface 205 of the light-emitting structure layer 2 can be the surface of the second conductive type semiconductor layer 203 facing away from the light-emitting layer 202, and the second surface 205 is aligned with the inner surface of the first recessed portion 101. Because the inner surface of the first recessed portion 101 is curved, the second surface 205 is convex toward the first recessed portion 101. In other words, the portion of the second surface 205 aligned with the first recessed portion 101 is also curved. In addition, the light-emitting structure layer 2 may further include sidewalls connecting the first surface 204 and the second surface 205.

[0054] like Figure 3 As shown, the materials of the potential well layer, barrier layer, first conductivity type semiconductor layer 201, and second conductivity type semiconductor layer 203 can all be Group III-V semiconductor materials, but this is not particularly limited in the present disclosure. For example, the material of the potential well layer is InGaN, the material of the barrier layer is GaN, the material of the first conductivity type semiconductor layer 201 is GaN, and the material of the second conductivity type semiconductor layer 203 is GaN.

[0055] Step S120 , forming a first reflector layer on the first surface.

[0056] like Figure 3 As shown, the first reflector layer 3 can be formed in the region of the first surface 204 corresponding to the first recess 101. Specifically, the first reflector layer 3 can be formed in the region of the first conductive type semiconductor layer 201 corresponding to the first recess 101. The boundary of the opening of the first recess 101 can surround the first reflector layer 3, that is, the area of ​​the first reflector layer 3 is smaller than the opening area of ​​the first recess 101. The first reflector layer 3 can be formed by evaporation coating, or alternatively, by sputtering coating, but the present disclosure is not limited thereto. The reflectivity of the first reflector layer 3 can be 99%-100%, but this is not particularly limited in the present disclosure. The number of first reflector layers 3 can be one, two, four, or more. For example, in the case where both the first recess 101 and the first reflector layer 3 are multiple, the multiple first reflector layers 3 correspond one-to-one to the multiple first recesses 101.

[0057] like Figure 3 As shown, the first reflector layer 3 is a Bragg reflector (DBR). The material of the Bragg reflector is a multi-periodic material selected from the group consisting of TiO2 / SiO2, Ti3O5 / SiO2, Ta2O5 / SiO2, Ti3O5 / Al2O3, ZrO2 / SiO2, or TiO2 / Al2O3, but the present disclosure is not limited thereto. Furthermore, taking the first reflector layer 3 as an example of a Bragg reflector, before forming the first reflector layer 3, this embodiment may further include: forming an ITO layer 4 on the first surface 204. The first reflector layer 3 may be formed on the ITO layer 4. The ITO layer 4 is an indium tin oxide layer.

[0058] In step S130 , the epitaxial substrate is removed to form a second reflective mirror layer covering the second surface.

[0059] like Figure 3As shown, before removing the epitaxial substrate 1, the disclosed embodiment may further include forming a support layer 5 that covers the first reflector layer 3. Specifically, the support layer 5 contacts the ITO layer 4, and the first reflector layer 3 is coated between the support layer 5 and the ITO layer 4. The support layer 5 may include a heavily doped silicon substrate 501 and a metal bonding layer 502. The epitaxial substrate 1 can be removed by a laser lift-off process.

[0060] like Figure 4 and Figure 5 As shown, taking the number of the first reflector layer 3 as an example, after removing the epitaxial substrate 1 and before forming the second reflector layer 8, the embodiment of the present disclosure may include: patterning the light emitting structure layer 2 to form an isolation trench 7, the light emitting structure layer 2 is divided into multiple parts by the isolation trench 7, each part of the light emitting structure layer 2 is provided with a first reflector layer 3, and the depth of the isolation trench 7 can be less than or equal to the thickness of the light emitting structure layer 2. Figure 4 As shown, when the depth of the isolation groove 7 is equal to the thickness of the light emitting structure layer 2, the above-mentioned ITO layer 4 is exposed through the isolation groove 7; Figure 5 As shown, when the depth of the isolation trench 7 is less than the thickness of the light emitting structure layer 2, the first conductive type layer is exposed through the isolation trench 7. Figure 6 As shown, the second reflector layer 8 can cover the second surface 205 of the light-emitting structure layer 2. Furthermore, while the second reflector layer 8 covers the second surface 205 of the light-emitting structure layer 2, the second reflector layer 8 can also cover the sidewalls of the light-emitting structure layer 2. The second reflector layer 8 can cover the entire sidewalls of the light-emitting structure layer 2, or, of course, it can also cover a portion of the sidewalls of the light-emitting structure layer 2, which is not specifically limited in this disclosure. The second reflector layer 8 can be a Bragg reflector. The reflectivity of the second reflector layer 8 can be greater than the reflectivity of the first reflector layer 3, or, of course, it can be less than the reflectivity of the first reflector layer 3. For example, the reflectivity of the second reflector layer 8 can be 50%-80%. In addition, the second reflector layer 8 can be made of an insulating material. Based on this, taking the example of the second reflector layer 8 covering the sidewalls of the light-emitting structure layer 2, the insulating second reflector layer 8 can serve as a protective layer for the light-emitting diode, protecting the top and sidewalls of the light-emitting diode, reducing the steps in manufacturing the insulating protective layer and saving costs.

[0061] The first embodiment of the present disclosure further provides a light-emitting device, which is manufactured by the above-mentioned method for manufacturing a light-emitting device and thus has the same beneficial effects, which will not be described in detail in the present disclosure.

[0062] Example 2

[0063] Figure 7Schematic diagram of the epitaxial substrate in the second embodiment of the present disclosure. The light-emitting device and the method for preparing the light-emitting device in the second embodiment of the present disclosure are substantially the same as those in the first embodiment of the present disclosure, and the only difference is the structure of the epitaxial substrate. Figure 7 As shown, the epitaxial substrate 1 of the second embodiment of the present disclosure includes, from bottom to top, a substrate 102 and a nucleation layer 103. The first recess 101 is formed in the substrate 102, and the nucleation layer 103 is conformally formed on the substrate 102. The nucleation layer 103 is conformally formed on the substrate 102, that is, the area of ​​the nucleation layer 103 corresponding to the first recess 101 protrudes toward the first recess 101, forming a recessed structure on the side of the nucleation layer 103 facing away from the substrate 102. The light-emitting structure layer 2 is grown on the side of the nucleation layer 103 facing away from the substrate 102.

[0064] Example 3

[0065] Figure 8 Schematic diagram of the epitaxial substrate in the third embodiment of the present disclosure. The light-emitting device and the method for preparing the light-emitting device in the third embodiment of the present disclosure are substantially the same as those in the first embodiment of the present disclosure, with the only difference being the structure of the epitaxial substrate and the method for removing the epitaxial substrate. Figure 8 As shown, the epitaxial substrate 1 of the third embodiment of the present disclosure includes, from bottom to top, a substrate 102, a dielectric layer 104, and a nucleation layer 103. The first recess 101 is formed within the dielectric layer 104, and the nucleation layer 103 is conformally formed on the dielectric layer 104. The dielectric layer 104 may be made of, for example, SiO2, but this is not particularly limited in the present embodiment. The epitaxial substrate 1 of the third embodiment of the present disclosure can be stripped using a chemical etching process. The etching solution used in this chemical etching process may be, for example, hydrofluoric acid.

[0066] Example 4

[0067] Figure 9 Schematic diagram of the light emitting device of the fourth embodiment of the present disclosure. The light emitting device and the method for manufacturing the light emitting device of the fourth embodiment of the present disclosure are substantially the same as the light emitting device and the method for manufacturing the light emitting device of any one of the first to third embodiments of the present disclosure, with the only difference being the first reflector layer. Figure 9 As shown, the first reflector layer 3 of the fourth embodiment of the present disclosure is a metal reflector. The material of the metal reflector can be Ag, Ni / Ag / Ni, etc. Furthermore, to prevent oxidation of the first reflector layer 3, the fourth embodiment of the present disclosure can also form a metal protective layer 6 covering the first reflector layer 3. The material of the metal protective layer 6 can be Ni, TiW, Pt, etc. The aforementioned support layer 5 can cover the metal protective layer 6.

[0068] Example 5

[0069] Figure 10 Schematic diagram of the light-emitting device of the fifth embodiment of the present disclosure. The light-emitting device and the method for preparing the light-emitting device of the fifth embodiment of the present disclosure are substantially the same as the light-emitting device and the method for preparing the light-emitting device of any one of the first to fourth embodiments of the present disclosure, with the only difference being: Figure 10 As shown, a first electrode 9 electrically connected to the first conductive type semiconductor layer 201 and a second electrode 10 electrically connected to the second conductive type semiconductor layer 203 are also formed. The first electrode 9 and the second electrode 10 can be located on both sides of the light emitting structure layer 2. Specifically, the first electrode 9 can be provided on the side of the support layer 5 away from the light emitting structure layer 2, and the second electrode 10 can be provided through the second reflector layer 8 and in contact with the light emitting structure layer 2. The light emitting device of the fifth embodiment of the present disclosure is a resonant cavity LED. Taking the first conductive type semiconductor layer 201 as a P-type semiconductor layer and the second conductive type semiconductor layer 203 as an N-type semiconductor layer as an example, the first electrode 9 is a P-type electrode and the second electrode 10 is an N-type electrode. The material of the first electrode 9 and the material of the second electrode 10 can be selected from at least one of gold, silver, aluminum, chromium, nickel, platinum, and titanium.

[0070] Example 6

[0071] Figure 11 Schematic diagram of the light emitting device of the sixth embodiment of the present disclosure. The light emitting device and the method for preparing the light emitting device of the sixth embodiment of the present disclosure are substantially the same as the light emitting device and the method for preparing the light emitting device of the fifth embodiment of the present disclosure, with the only difference being: Figure 11 As shown, the first electrode 9 and the second electrode 10 are both located on the side of the first conductive type semiconductor layer 201 away from the first reflector layer 3. Specifically, the first electrode 9 can be provided on the surface of the first conductive type semiconductor layer 201 facing away from the first reflector layer 3, and the second electrode 10 can be provided through the second reflector layer 8 and in contact with the light emitting structure layer 2. The light emitting device in the sixth embodiment of the present disclosure is a resonant cavity LED. When the first reflector layer 3 is a Bragg reflector, an ITO layer is not required between the first reflector layer 3 and the first conductive type semiconductor layer 201.

[0072] Example 7

[0073] Figure 12 This is a schematic diagram of a light-emitting device according to a seventh embodiment of the present disclosure. Figure 13 This is another schematic diagram of the light-emitting device of the seventh embodiment of the present disclosure. The light-emitting device and the method for preparing the light-emitting device of the seventh embodiment of the present disclosure are substantially the same as the light-emitting device and the method for preparing the light-emitting device of any one of the first to fifth embodiments of the present disclosure, with the only difference being the light-emitting structure layer. Figure 12 and Figure 13As shown, the light-emitting structure layer 2 of the seventh embodiment of the present disclosure may include an active layer 20 and an oxide layer 21 arranged in a stacked manner. The oxide layer 21 may include a low resistance region 211 and a high resistance region 212. The high resistance region 212 surrounds the low resistance region 211, and the low resistance region 211 forms a current aperture, i.e., an internal current window, so that the light-emitting device of the seventh embodiment of the present disclosure constitutes a vertical cavity surface emitting laser (VCSEL). Among them, the low resistance region 211 also forms an optical path of the vertical cavity surface emitting laser.

[0074] like Figure 12 and Figure 13 As shown, the active layer 20 may include a first conductive type semiconductor layer 201, a light emitting layer 202, and a second conductive type semiconductor layer 203 that are stacked. Figure 12 As shown, the oxide layer 21 can also be located on the side of the second conductive type semiconductor layer 203 away from the light emitting layer 202, that is, the second surface of the light emitting structure layer 2 is the surface of the oxide layer 21 facing away from the second conductive type semiconductor layer 203. Figure 13 As shown, the oxide layer 21 can be located on the side of the first conductive type semiconductor layer 201 away from the light emitting layer 202, that is, the first surface of the light emitting structure layer 2 is the surface of the oxide layer 21 facing away from the first conductive type semiconductor layer 201. In addition, the oxide layer 21 can also be located in the light emitting layer 202. There can be multiple oxide layers 21. Taking the number of oxide layers 21 as two as an example, one oxide layer 21 can be located in the light emitting layer 202, and the other oxide layer 21 can be located on the side of the first conductive type semiconductor layer 201 away from the light emitting layer 202. The oxide layer 21 of the embodiment of the present disclosure can be obtained by oxidizing a single layer structure of AlInN, AlGaAs, AlAs or AlN, or by oxidizing AlInN / GaN, AlN / GaN, AlGaAs / GaN or AlAs / GaN.

[0075] The above description is merely a preferred embodiment of the present disclosure and does not constitute any form of limitation to the present disclosure. Although the present disclosure has been disclosed as a preferred embodiment as above, it is not intended to limit the present disclosure. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical content disclosed above without departing from the scope of the technical solution of the present disclosure. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present disclosure without departing from the content of the technical solution of the present disclosure are still within the scope of the technical solution of the present disclosure.

Claims

1. A method for preparing a light-emitting device, characterized in that: include: An epitaxial substrate (1) is provided, wherein the epitaxial substrate (1) has a first recessed portion (101), and the inner surface of the first recessed portion (101) is a curved surface; Epitaxially growing a light-emitting structure layer (2) on the epitaxial substrate (1), the light-emitting structure layer (2) comprising a first surface (204) and a second surface (205) opposite to each other, the second surface (205) protruding toward the first recessed portion (101); forming a first reflector layer (3) on the first surface (204); removing the epitaxial substrate (1) to form a second reflector layer (8) covering the second surface (205); The light emitting structure layer (2) further comprises a side wall connecting the first surface (204) and the second surface (205), and the second reflector layer (8) covering the second surface (205) comprises: A second reflector layer (8) is formed to cover the sidewalls of the light-emitting structure layer (2) and the second surface (205).

2. The method for preparing a light-emitting device according to claim 1, wherein: The epitaxial base (1) comprises a substrate (102), and the first recessed portion (101) is formed in the substrate (102).

3. The method for preparing a light-emitting device according to claim 1, wherein: The epitaxial base (1) comprises a substrate (102) and a nucleation layer (103) from bottom to top, the first recessed portion (101) is formed in the substrate (102), and the nucleation layer (103) is conformally formed on the substrate (102).

4. The method for preparing a light-emitting device according to claim 1, wherein: The epitaxial base (1) comprises, from bottom to top, a substrate (102), a dielectric layer (104) and a nucleation layer (103); the first recessed portion (101) is formed in the dielectric layer (104); and the nucleation layer (103) is conformally formed on the dielectric layer (104).

5. The method for preparing a light-emitting device according to claim 1, wherein: The number of the first recessed portions (101) is plural.

6. The method for preparing a light-emitting device according to claim 1, wherein: The reflectivity of the second reflector layer (8) is 50%-80%.

7. The method for preparing a light-emitting device according to claim 1, wherein: The second reflector layer (8) is made of insulating material.

8. The method for preparing a light-emitting device according to claim 1, wherein: The light emitting structure layer (2) comprises an active layer (20), wherein the active layer (20) comprises, from top to bottom, a first conductive type semiconductor layer (201), a light emitting layer (202), and a second conductive type semiconductor layer (203), and the preparation method further comprises: forming a first electrode (9) electrically connected to the first conductive type semiconductor layer (201); A second electrode (10) electrically connected to the second conductive type semiconductor layer (203) is formed.

9. The method for preparing a light-emitting device according to claim 8, wherein: The first electrode (9) and the second electrode (10) are located on both sides of the light-emitting structure layer (2).

10. The method for preparing a light-emitting device according to claim 9, wherein: The first electrode (9) and the second electrode (10) are both located on a side of the first conductive type semiconductor layer (201) away from the first reflector layer (3).

11. The method for preparing a light-emitting device according to claim 1, wherein: The light emitting structure layer (2) comprises an active layer (20) and an oxide layer (21) which are stacked, and the oxide layer (21) comprises a low resistance region (211) and a high resistance region (212) surrounding the low resistance region (211).

12. A light emitting device, characterized in that: The light-emitting device is prepared by the method for preparing a light-emitting device according to any one of claims 1 to 11.

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