Multi-color LED chip and manufacturing method thereof

Abstract

The application provides a multi-color LED chip and a manufacturing method thereof. A first reflection layer, a first type limiting layer, an active region, a second type limiting layer, a composite current spreading structure and an ohmic contact layer are sequentially stacked on a substrate surface. The composite current spreading structure comprises a current spreading bottom layer, a second reflection layer, a third reflection layer and a current spreading top layer which are sequentially stacked along a first direction. Light waves reflected by the first reflection layer, the second reflection layer and the third reflection layer are sequentially reduced to realize a multi-color three-dimensional display effect of a single LED chip. Based on this, the wavelength bands reflected from the bottom surface of the light-emitting epitaxial structure are gradually reduced, and the light-emitting epitaxial structure surface is effectively prevented from emitting light downward to the active region to reduce light loss, and the lateral current spreading of the light-emitting epitaxial structure surface can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of light emitting diodes, in particular to a multi-color LED chip and a manufacturing method thereof. BACKGROUND

[0002] In recent years, III-V nitrides have been widely concerned and applied in the fields of electricity and optics due to their excellent physical and chemical properties (large band gap, high breakdown field, high electron saturation mobility, etc.).

[0003] In the prior art, LED chips are generally single-color chips, and a single chip cannot obtain full-color effect, which has the following defects: each chip is transferred to a substrate by a die bonding device, three chips are needed in each pixel point, and the production capacity per unit time is limited; three independent RGB LED chips limit the minimum pixel point spacing of the display screen; and the processing cost of downstream enterprises is high. At the same time, after the rise of Micro-LED technology, due to the reduction of the size and spacing of LED chips, the distance between each group of RGB is correspondingly shortened, which causes color mixing; on the other hand, the massive transfer of Micro-LED mixes each group of RGB in a complex process, which leads to a low yield in mass production and high production cost.

[0004] Therefore, the present application has been developed to solve the above problems. SUMMARY

[0005] The present application aims to provide a multi-color LED chip and a manufacturing method thereof to form a single LED chip with a multi-color three-dimensional display effect.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A multi-color LED chip, comprising:

[0008] a substrate and a first reflective layer, a first type confinement layer, an active region, a second type confinement layer, a composite current spreading structure and an ohmic contact layer which are sequentially stacked along the surface of the substrate, and each functional layer of the active region close to the substrate side is an N-type doped layer, and each functional layer of the active region away from the substrate side is a P-type doped layer; wherein the composite current spreading structure at least includes a current spreading bottom layer, a second reflective layer, a third reflective layer and a current spreading top layer which are sequentially stacked along a first direction; and the light waves reflected by the first reflective layer, the second reflective layer and the third reflective layer are sequentially reduced; the first direction is perpendicular to the substrate and points from the substrate to the first reflective layer.

[0009] Preferably, a first waveguide layer is arranged between the first type confinement layer and the active region, and a barrier height of the first type confinement layer is higher than a barrier height of the first waveguide layer.

[0010] Preferably, a second waveguide layer is arranged between the active region and the second type confinement layer, and a barrier height of the second type confinement layer is higher than a barrier height of the second waveguide layer.

[0011] Preferably, the first reflective layer, the first type confinement layer, the active region and the second type confinement layer form a red light emitting epitaxial structure.

[0012] Preferably, the second reflective layer is used for reflecting green light.

[0013] Preferably, the third reflective layer is used for reflecting blue light.

[0014] Preferably, the red light emitting epitaxial structure comprises an AlGaInP-based epitaxial structure.

[0015] Preferably, a thickness of the current spreading bottom layer is greater than a thickness of the current spreading top layer.

[0016] Preferably, each layer in the composite current spreading structure comprises one or more of AlGaP, AlGaInP and AlGaAs with different Al components.

[0017] Preferably, the second reflective layer and the third reflective layer respectively comprise DBR reflective layers composed of any two semiconductor epitaxial materials, and Al components of the second reflective layer and the third reflective layer are respectively higher than Al components of the current spreading bottom layer and / or the current spreading top layer.

[0018] The application also provides a manufacturing method of a multi-color LED chip, which comprises the following steps:

[0019] Step S01, providing a substrate;

[0020] Step S02, sequentially growing, on a surface of the substrate, a first reflective layer, a first type confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second type confinement layer, a composite current spreading structure and an ohmic contact layer, wherein each functional layer on a side of the active region close to the substrate is an N-type doped layer, and each functional layer on a side of the active region away from the substrate is a P-type doped layer; wherein the composite current spreading structure at least comprises a current spreading bottom layer, a second reflective layer, a third reflective layer and a current spreading top layer stacked in sequence along a growth direction; and light waves reflected by the first reflective layer, the second reflective layer and the third reflective layer decrease in sequence;

[0021] The barrier height of the first type confinement layer is higher than the barrier height of the first waveguide layer, the barrier height of the second type confinement layer is higher than the barrier height of the second waveguide layer, and the thickness of the current spreading bottom layer is greater than the thickness of the current spreading top layer.

[0022] Preferably, the first reflective layer, the first type confinement layer, the active region and the second type confinement layer form a red light emitting epitaxial structure, the second reflective layer is used for reflecting green light, and the third reflective layer is used for reflecting blue light.

[0023] The red light emitting epitaxial structure comprises an AlGaInP-based epitaxial structure, and each layer in the composite current spreading structure comprises one or more of AlGaP, AlGaInP and AlGaAs with different Al components.

[0024] Preferably, the second reflective layer and the third reflective layer each comprise a DBR reflective layer composed of any two semiconductor epitaxial materials, and the Al components of the second reflective layer and the third reflective layer are higher than the Al components of the current spreading bottom layer and / or the current spreading top layer.

[0025] The growth temperatures of the second reflective layer and the third reflective layer are lower than the growth temperatures of the current spreading bottom layer and / or the current spreading top layer, and the second reflective layer and the third reflective layer are processed in a variable temperature growth mode to treat the interfaces of different material layers in the DBR reflective layer, in particular, the interfaces in the DBR reflective layer are raised in temperature and the input of Al and P type doping is increased.

[0026] According to the technical solution, the multi-color LED chip comprises a first reflective layer, a first type confinement layer, an active region, a second type confinement layer, a composite current spreading structure and an ohmic contact layer which are sequentially stacked on the surface of a substrate, wherein the composite current spreading structure comprises a current spreading bottom layer, a second reflective layer, a third reflective layer and a current spreading top layer which are sequentially stacked along a first direction, and the light waves reflected by the first reflective layer, the second reflective layer and the third reflective layer are sequentially reduced to realize the multi-color three-dimensional display effect of a single LED chip.

[0027] Secondly, by the second reflective layer and the third reflective layer respectively comprising DBR reflective layers composed of any two semiconductor epitaxial materials, and the Al components of the second reflective layer and the third reflective layer are respectively higher than the Al components of the current spreading bottom layer and / or the current spreading top layer. The materials and components in the DBR reflective layer can be effectively utilized to make the current better realize local longitudinal blocking in the current spreading bottom layer and / or the current spreading top layer, and further better realize the current spreading ability in the horizontal direction.

[0028] The application further provides a manufacturing method of the multi-color LED chip, which is simple in operation and easy to realize while realizing the above technical effects.

[0029] Meanwhile, in the manufacturing process of the composite current spreading structure, the growth temperature of the second reflective layer and the third reflective layer is respectively lower than the growth temperature of the current spreading bottom layer and / or the current spreading top layer by the gradient design of the growth temperature, and the second reflective layer and the third reflective layer adopt the variable-temperature growth mode to process the interfaces of different material layers in the DBR reflective layer, especially the cyclic interface temperature rising and the increase of the input of Al and P type doping in the DBR reflective layer. Therefore, the composite current spreading structure has higher crystal quality, and the material reflection interface and the doping interface are clearer on the cyclic interfaces of different materials in the second reflective layer and the third reflective layer, so that the internal quantum and external quantum efficiencies of the light emitting epitaxial structure are effectively improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on the provided drawings.

[0031] Figure 1 The structure schematic diagram of the multi-color LED chip provided by the embodiments of the present application;

[0032] Figure 2 The change schematic diagram of the growth temperature of each functional layer in the multi-color LED chip provided by the embodiments of the present application along the growth direction;

[0033] Symbols in the diagram: 1. Substrate; 2. Buffer layer; 3. First reflective layer; 4. Type I confinement layer; 5. First waveguide layer; 6. Active region; 61. Quantum barrier; 62. Quantum well; 7. Second waveguide layer; 8. Type II confinement layer; 9. Current spreading bottom layer; 10. Second reflective layer; 11. Third reflective layer; 12. Current spreading top layer; 13. Ohmic contact layer. Detailed Implementation

[0034] To make the content of this invention clearer, the following description, in conjunction with the accompanying drawings, further illustrates the invention. This invention is not limited to this specific embodiment. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0035] like Figure 1 As shown, a multi-color LED chip includes:

[0036] The substrate 1 and the first reflective layer 3, the first type confinement layer 4, the active region 6, the second type confinement layer 8, the composite current extension structure, and the ohmic contact layer 13 are stacked sequentially along the surface of the substrate 1. Each functional layer on the side of the active region 6 near the substrate 1 is N-type doped, and each functional layer on the side of the active region 6 away from the substrate 1 is P-type doped. The composite current extension structure includes at least a current extension bottom layer 9, a second reflective layer 10, a third reflective layer 11, and a current extension top layer 12 stacked sequentially along a first direction. The light waves reflected by the first reflective layer 3, the second reflective layer 10, and the third reflective layer 11 decrease sequentially. The first direction is perpendicular to the substrate 1 and points from the substrate 1 to the first reflective layer 3.

[0037] It should be noted that, in this embodiment, the substrate 100 is preferably a gallium arsenide substrate.

[0038] Furthermore, the N-type dopant can be at least one of silicon (Si) and tellurium (Te), but is not limited thereto. Further, the first type dopant is preferably Si.

[0039] Accordingly, the N-type dopant can be at least one of magnesium (Mg) and zinc (Zn), but is not limited thereto. Further, the second type dopant is preferably Mg.

[0040] Furthermore, based on the above embodiments of the present invention, a first waveguide layer 5 is provided between the first type of confinement layer 4 and the active region 6, and the barrier height of the first type of confinement layer 4 is higher than the barrier height of the first waveguide layer 5.

[0041] Furthermore, based on the above embodiments of the present invention, a second waveguide layer 7 is provided between the active region 6 and the second type confinement layer 8, and the barrier height of the second type confinement layer 8 is higher than the barrier height of the second waveguide layer 7.

[0042] Further, based on the above embodiment of the present application, the first reflective layer 3, the first confinement layer 4, the active region 6 and the second confinement layer 8 form a red light emitting epitaxial structure.

[0043] Further, based on the above embodiment of the present application, the second reflective layer 10 is used for reflecting green light.

[0044] Further, based on the above embodiment of the present application, the third reflective layer 11 is used for reflecting blue light.

[0045] Further, based on the above embodiment of the present application, the red light emitting epitaxial structure comprises an AlGaInP-based epitaxial structure.

[0046] In a specific embodiment of the present application, the active region 6 adopts a non-doped AlGaInP (quantum barrier 61) / AlGaInP (quantum well 62) with quantum barriers 61 and quantum wells 62 alternating with each other, and the Al component of the AlGaInP (quantum barrier 61) is higher than that of the AlGaInP (quantum well 62).

[0047] The first and second confinement layers and the first and second waveguide layers are composed of AlGaInP with different Al components, and the Al component of the first confinement layer 4 is higher than that of the first waveguide layer 5, and the Al component of the second confinement layer 8 is higher than that of the second waveguide layer 7.

[0048] Further, based on the above embodiment of the present application, the thickness of the current spreading bottom layer 9 is greater than that of the current spreading top layer 12.

[0049] Further, based on the above embodiment of the present application, each layer in the composite current spreading structure comprises one or more of AlGaP, AlGaInP and AlGaAs with different Al components.

[0050] Further, based on the above embodiment of the present application, the second reflective layer 10 and the third reflective layer 11 respectively comprise DBR reflective layers composed of any two of the above semiconductor epitaxial materials, and the Al components of the second reflective layer 10 and the third reflective layer 11 are respectively higher than the Al components of the current spreading bottom layer 9 and / or the current spreading top layer 12.

[0051] It should be noted that the thickness of each layer of the second reflective layer is 1 / 4n of the center wavelength of reflection (i.e. green wave), and the thickness of each layer of the third reflective layer is 1 / 4n of the center wavelength of reflection (i.e. blue wave). The present embodiment does not limit the number of periods of the second reflective layer 10 and the third reflective layer 11.

[0052] In a specific embodiment, the current spreading bottom layer 9 is (Al 0.4 Ga0.6 ) 0.5 In 0.5 P, the second reflective layer 10 is composed of (Al) 0.4 Ga 0.6 ) 0.5 In 0.5 P / Al 0.5 Ga 0.5 The DBR reflective layer is composed of As, and the third reflective layer 11 is composed of (Al) 0.5 Ga 0.5 ) 0.5 In 0.5 P / Al 0.6 Ga 0.4 The DBR reflective layer composed of As has a current-extending top layer 12 made of (Al) 0.45 Ga 0.55 ) 0.5 In 0.5 P.

[0053] Furthermore, based on the above embodiments of the present invention, a buffer layer 2 is further provided between the substrate 1 and the first reflective layer 3. In this embodiment, the buffer layer 2 can be any one or more of an AlN buffer layer, a GaAs buffer layer, a GaN buffer layer, or an AlGaN buffer layer; in this embodiment, a GaAs buffer layer is preferred.

[0054] This invention also provides a method for manufacturing a multi-color LED chip, the method comprising the following steps:

[0055] Step S01: Provide a substrate 1;

[0056] Step S02: A first reflective layer 3, a first type confinement layer 4, a first waveguide layer 5, an active region 6, a second waveguide layer 7, a second type confinement layer 8, a composite current extension structure, and an ohmic contact layer 13 are sequentially grown on the surface of substrate 1. Each functional layer on the side of the active region 6 closest to substrate 1 is an N-type doped layer, and each functional layer on the side of the active region 6 away from substrate 1 is a P-type doped layer. The composite current extension structure includes at least a current extension bottom layer 9, a second reflective layer 10, a third reflective layer 11, and a current extension top layer 12 stacked sequentially along the growth direction. The light waves reflected by the first reflective layer 3, the second reflective layer 10, and the third reflective layer 11 decrease sequentially.

[0057] Among them, the barrier height of the first type confinement layer 4 is higher than that of the first waveguide layer 5; the barrier height of the second type confinement layer 8 is higher than that of the second waveguide layer 7; and the thickness of the current-spreading bottom layer 9 is greater than that of the current-spreading top layer 12.

[0058] Further, based on the above-mentioned embodiments of the present application, the first reflective layer 3, the first type confinement layer 4, the active region 6 and the second type confinement layer 8 are the light-emitting epitaxial structure for red light; the second reflective layer 10 is used for reflecting green light; and the third reflective layer 11 is used for reflecting blue light.

[0059] The light-emitting epitaxial structure for red light comprises an AlGaInP-based epitaxial structure; and the layers in the composite current spreading structure comprise one or more of AlGaP, AlGaInP and AlGaAs with different Al components.

[0060] In a specific embodiment of the present application, the active region 6 adopts a non-doped AlGaInP (quantum barrier 61) / AlGaInP (quantum well 62) with quantum barriers 61 and quantum wells 62 alternating with each other, and the Al component of the AlGaInP (quantum barrier 61) is higher than that of the AlGaInP (quantum well 62).

[0061] The first and second type confinement layers and the first and second waveguide layers are composed of AlGaInP with different Al components, and the Al component of the first type confinement layer 4 is higher than that of the first waveguide layer 5, and the Al component of the second type confinement layer 8 is higher than that of the second waveguide layer 7.

[0062] Further, based on the above-mentioned embodiments of the present application, the second reflective layer 10 and the third reflective layer 11 each comprise a DBR reflective layer composed of any two semiconductor epitaxial materials, and the Al components of the second reflective layer 10 and the third reflective layer 11 are respectively higher than the Al components of the current spreading bottom layer 9 and / or the current spreading top layer 12; in a specific embodiment, the current spreading bottom layer 9 is (Al 0.4 Ga 0.6 ) 0.5 In 0.5 P, the second reflective layer 10 is a DBR reflective layer composed of (Al 0.4 Ga 0.6 ) 0.5 In 0.5 P / Al 0.5 Ga 0.5 As, the third reflective layer 11 is a DBR reflective layer composed of (Al 0.5 Ga 0.5 ) 0.5 In 0.5 P / Al 0.6 Ga 0.4 As, and the current spreading top layer 12 is (Al 0.45 Ga 0.55 ) 0.5 In 0.5 P.

[0063] The growth temperature of the second reflective layer 10 and the third reflective layer 11 is lower than the growth temperature of the current spreading bottom layer 9 and / or the current spreading top layer 12, respectively. Figure 2 The second reflective layer 10 and the third reflective layer 11 are used to process the interface of different material layers in the DBR reflective layer by means of variable temperature growth, and in particular, the temperature of the interface of the DBR reflective layer is raised to the highest point and the input of Al and P type doping is increased.

[0064] According to the technical solution, the multi-color LED chip comprises a substrate 1, a first reflective layer 3, a first type confinement layer 4, an active region 6, a second type confinement layer 8, a composite current spreading structure and an ohmic contact layer 13 which are sequentially stacked on the surface of the substrate 1; the composite current spreading structure comprises a current spreading bottom layer 9, a second reflective layer 10, a third reflective layer 11 and a current spreading top layer 12 which are sequentially stacked along a first direction; and the light reflected by the first reflective layer 3, the second reflective layer 10 and the third reflective layer 11 is sequentially reduced, so that the multi-color three-dimensional display effect of a single LED chip is realized. Based on this, the wavelength band reflected from the bottom surface of the light emitting epitaxial structure is gradually reduced, and the light emitted from the surface of the light emitting epitaxial structure is effectively prevented from being emitted downward to the active region 6 and wasted, and the lateral current spreading of the surface of the light emitting epitaxial structure is realized.

[0065] Secondly, the second reflective layer 10 and the third reflective layer 11 each comprise a DBR reflective layer composed of any two semiconductor epitaxial materials, and the Al component of the second reflective layer 10 and the third reflective layer 11 is higher than the Al component of the current spreading bottom layer 9 and / or the current spreading top layer 12. The different materials and components in the DBR reflective layer are effectively utilized to better realize the local longitudinal blocking of the current spreading bottom layer 9 and / or the current spreading top layer 12, and the lateral current spreading ability of the current is better realized.

[0066] The application further provides a manufacturing method of the multi-color LED chip, which is simple in operation and easy to realize.

[0067] Meanwhile, the manufacturing method of the multi-color LED chip provided by the application, in the manufacturing process of the composite current spreading structure, the growth temperature gradient is designed, the growth temperature of the second reflection layer 10 and the third reflection layer 11 is lower than the growth temperature of the current spreading bottom layer 9 and / or the current spreading top layer 12 respectively, and the second reflection layer 10 and the third reflection layer 11 adopt the variable temperature growth mode to process the interface of different material layers in the DBR reflection layer, especially in the cycle interface of the DBR reflection layer, the temperature is raised and the input of Al and P type doping is improved. Therefore, the composite current spreading structure has higher crystal quality, and the material reflection interface and the doping interface on the cycle interface of different materials in the second reflection layer 10 and the third reflection layer 11 are clearer, so that the internal quantum and external quantum efficiency of the light emitting epitaxial structure are effectively improved.

[0068] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

[0069] It should also be noted that the relational terms herein such as first and second and the like are used only to distinguish one entity or operation from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In addition, the terms "comprise", "contain" or any other variant thereof are intended to cover non-exclusive inclusion, so that the article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the article or device including the above element.

[0070] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the present application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-color LED chip, characterized by, The application relates to a light-emitting diode (LED) wafer, which comprises a substrate and a first reflective layer, a first type confinement layer, an active region, a second type confinement layer, a composite current spreading structure and an ohmic contact layer which are sequentially stacked along the surface of the substrate, and each functional layer of the active region close to the substrate is an N-type doped layer, and each functional layer of the active region away from the substrate is a P-type doped layer; wherein the composite current spreading structure at least comprises a current spreading bottom layer, a second reflective layer, a third reflective layer and a current spreading top layer which are sequentially stacked along a first direction; and the light waves reflected by the first reflective layer, the second reflective layer and the third reflective layer are sequentially reduced; and the first direction is perpendicular to the substrate and points from the substrate to the first reflective layer. A first waveguide layer is arranged between the first type confinement layer and the active region, and the barrier height of the first type confinement layer is higher than the barrier height of the first waveguide layer.

2. The multi-color LED chip of claim 1, wherein, A second waveguide layer is arranged between the active region and the second type confinement layer, and the barrier height of the second type confinement layer is higher than the barrier height of the second waveguide layer.

3. The multi-color LED chip of claim 1, wherein, The first reflective layer, the first type confinement layer, the active region and the second type confinement layer are a light-emitting epitaxial structure of red light.

4. The multi-color LED chip of claim 1, wherein, The second reflective layer is used for reflecting green light.

5. The multi-color LED chip of claim 4, wherein, The third reflective layer is used for reflecting blue light.

6. The multi-color LED chip of claim 5, wherein, The light-emitting epitaxial structure of red light comprises an AlGaInP-based epitaxial structure.

7. The multi-color LED chip of claim 4, wherein, The thickness of the current spreading bottom layer is greater than the thickness of the current spreading top layer.

8. The multi-color LED chip of claim 1, wherein, Each layer in the composite current spreading structure comprises one or more of AlGaP, AlGaInP and AlGaAs with different Al components.

9. The multi-color LED chip of claim 7, wherein, The second reflective layer and the third reflective layer respectively comprise DBR reflective layers composed of any two semiconductor epitaxial materials, and the Al components of the second reflective layer and the third reflective layer are respectively higher than the Al components of the current spreading bottom layer and / or the current spreading top layer.

10. The multi-color LED chip of claim 1, wherein, The manufacturing method comprises the following steps:

11. A method of fabricating a multi-color LED chip, comprising: Step S01: providing a substrate; Step S02: sequentially growing a first reflective layer, a first type confinement layer, a first waveguide layer, an active region, a second waveguide layer, a second type confinement layer, a composite current spreading structure and an ohmic contact layer on the surface of the substrate, and each functional layer of the active region close to the substrate is an N-type doped layer, and each functional layer of the active region away from the substrate is a P-type doped layer; wherein the composite current spreading structure at least comprises a current spreading bottom layer, a second reflective layer, a third reflective layer and a current spreading top layer which are sequentially stacked along the growth direction; and the light waves reflected by the first reflective layer, the second reflective layer and the third reflective layer are sequentially reduced. The barrier height of the first type confinement layer is higher than the barrier height of the first waveguide layer; the barrier height of the second type confinement layer is higher than the barrier height of the second waveguide layer; and the thickness of the current spreading bottom layer is greater than the thickness of the current spreading top layer. The first reflective layer, the first type confinement layer, the active region and the second type confinement layer are a light-emitting epitaxial structure of red light; the second reflective layer is used for reflecting green light; and the third reflective layer is used for reflecting blue light.

12. The method of claim 11, wherein the method further comprises: ​ The light-emitting epitaxial structure of the red light comprises an AlGaInP-based epitaxial structure; and each layer in the composite current spreading structure comprises one or more of AlGaP, AlGaInP and AlGaAs with different Al components.

13. The method of claim 11, wherein the method further comprises: The second reflective layer and the third reflective layer each comprise a DBR reflective layer composed of any two semiconductor epitaxial materials, and the Al components of the second reflective layer and the third reflective layer are higher than the Al components of the current spreading bottom layer and / or the current spreading top layer. The growth temperatures of the second reflective layer and the third reflective layer are lower than the growth temperatures of the current spreading bottom layer and / or the current spreading top layer.

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