Preparation method of light-emitting diode epitaxial wafer, light-emitting diode epitaxial wafer and equipment

Abstract

The invention provides a preparation method of a light-emitting diode epitaxial wafer, the light-emitting diode epitaxial wafer and equipment. The preparation method of the light-emitting diode comprises the following steps: sequentially depositing an aluminum nitride buffer layer and an aluminum gallium nitride layer on a substrate; depositing a first heterogeneous layer on the aluminum gallium nitride layer; etching a part of the substrate composite layer; sequentially depositing a second heterogeneous layer and a third heterogeneous layer; sequentially depositing a gallium nitride layer, an N-type gallium nitride layer, a light-emitting layer and a P-type gallium nitride layer; and stripping the substrate to form a composite epitaxial wafer, and corroding part of the composite epitaxial wafer by adopting a sodium hydroxide solution to form the light-emitting diode epitaxial wafer. The patterned initial composite substrate is obtained by etching the substrate composite layer, and the grown epitaxial wafer has the advantage of high external quantum efficiency; by arranging the second heterogeneous layer and the third heterogeneous layer, when the substrate is peeled off, damage to the epitaxial structure is avoided, the method for obtaining the graphical epitaxial structure through corrosion is simple, and the graphical epitaxial structure with higher quality can be obtained.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a method for preparing a light emitting diode epitaxial wafer, a light emitting diode epitaxial wafer and equipment. Background Art

[0002] Light-emitting diodes are electronic components that convert electrical energy into light energy. Light-emitting diode epitaxial wafers are the basic structure of light-emitting diodes. Existing light-emitting diode epitaxial wafers are usually grown on patterned or non-patterned substrates, including aluminum nitride buffer layers, N-type gallium nitride layers, light-emitting layers, and P-type gallium nitride layers.

[0003] The luminous efficiency of light emitting diodes is affected by internal quantum efficiency and external quantum efficiency. The light emitting diode epitaxial sheet grown using a flat non-patterned substrate has a problem of low external quantum efficiency. The patterned substrate usually has multiple convex structures on the substrate surface, which is beneficial to obtaining the patterned epitaxial sheet, changing the light output angle, improving the external quantum efficiency of the epitaxial sheet, and further improving the light efficiency of the light emitting diode.

[0004] However, substrate peeling is required in the preparation process of light-emitting diodes. For patterned substrates, there are height differences and uneven interface inclinations at the peeling interface between the substrate and the epitaxial structure. The peeling process can easily cause abnormal conditions such as hidden cracks and peeling surface damage in the light-emitting diode epitaxial wafer, resulting in low peeling quality, making it difficult to achieve both external quantum efficiency and peeling quality of the light-emitting diode epitaxial wafer. Summary of the invention

[0005] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a method for preparing a light-emitting diode epitaxial wafer, a light-emitting diode epitaxial wafer and an apparatus, aiming to solve the problem in the prior art that it is difficult to achieve both external quantum efficiency and peeling quality of the light-emitting diode epitaxial wafer.

[0006] In order to achieve the above object, the present invention is implemented by the following technical solutions:

[0007] A method for preparing a light emitting diode epitaxial wafer comprises the following steps:

[0008] Providing a substrate, and sequentially depositing an aluminum nitride buffer layer and an aluminum gallium nitride layer on the substrate;

[0009] A first heterogeneous layer is deposited on the aluminum gallium nitride layer. The aluminum nitride buffer layer, the aluminum gallium nitride layer and the first heterogeneous layer are combined to form a substrate composite layer. The thickness of the first heterogeneous layer is in the range of

[0010]

[0011] Etching part of the substrate composite layer until the substrate is exposed, the etched substrate composite layer forms a plurality of substrate composite parts, the substrate composite parts include a plurality of first heterogeneous parts formed by the etched first heterogeneous layer, and the plurality of substrate composite parts and the substrate are combined to form an initial composite substrate;

[0012] Depositing a second heterogeneous layer and a third heterogeneous layer in sequence on the initial composite substrate to form a final composite substrate;

[0013] Depositing a gallium nitride layer, an N-type gallium nitride layer, a light-emitting layer, and a P-type gallium nitride layer on the final composite substrate in sequence to form an epitaxial structure, wherein a top surface height of the gallium nitride layer is lower than a top height of the first heterogeneous portion;

[0014] The substrate is peeled off to form a composite epitaxial wafer, and a sodium hydroxide solution is used to etch one end of the composite epitaxial wafer facing away from the P-type gallium nitride layer until the etching reaches the gallium nitride layer to form a light-emitting diode epitaxial wafer.

[0015] Compared with the prior art, the advantageous effect of the present invention is that by depositing the aluminum nitride buffer layer, the aluminum gallium nitride layer and the first heterolayer on the substrate, forming the substrate composite layer, etching the substrate composite layer to obtain the raised substrate composite part on the substrate surface, and obtaining the patterned initial composite substrate. The epitaxial sheet grown with a patterned substrate has the advantage of high external quantum efficiency; by depositing the second heterolayer and the third heterolayer on the initial composite substrate, it is not only beneficial to improve the subsequent growth quality of the epitaxial structure, but also to make the epitaxial structure have a space between the epitaxial structure and the substrate, avoiding direct contact. When the substrate is peeled off, whether the peeling process produces hidden cracks or the peeling surface damage only affects the second heterolayer and the third heterolayer, and avoids the epitaxial structure. Due to the material differences, the corrosion rate of the second heterogeneous layer, the third heterogeneous layer and the aluminum gallium nitride layer in the sodium hydroxide solution is different from the gallium nitride layer in the epitaxial structure. The gallium nitride layer in the sodium hydroxide solution is slow, so the method of further obtaining a complete patterned epitaxial structure through corrosion is simpler, and compared with the traditional physical peeling method that is prone to cause cracking and damage, a higher quality patterned epitaxial structure can be obtained; by providing the thicker first heterogeneous layer, when the composite epitaxial sheet is corroded to the gallium nitride layer, the first heterogeneous portion and part of the heterogeneous layer surrounding the first heterogeneous portion remain in the light emitting diode epitaxial sheet, and the light emitting diode epitaxial sheet has a high-quality patterned structure, which is beneficial to improving the light output angle and improving the external quantum efficiency.

[0016] Furthermore, the thickness of the aluminum nitride buffer layer is in the range of

[0017] Furthermore, the thickness of the aluminum gallium nitride layer is in the range of

[0018] Furthermore, the material of the second heterogeneous layer is aluminum nitride, and the thickness of the second heterogeneous layer is in the range of The material of the third heterogeneous layer is aluminum gallium nitride, and the thickness of the third heterogeneous layer is equal to the thickness of the aluminum gallium nitride layer.

[0019] Furthermore, the thickness of the gallium nitride layer is in the range of

[0020] Furthermore, the first heterogeneous portion is cone-shaped.

[0021] The embodiment of the present invention further provides a light emitting diode epitaxial wafer, which is prepared by the light emitting diode preparation method described in the above technical solution.

[0022] An embodiment of the present invention further provides a device, comprising the light emitting diode epitaxial wafer described in the above technical solution. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Flow chart of a method for preparing a light emitting diode epitaxial wafer according to an embodiment of the present invention;

[0024] Figure 2 It is a schematic diagram of preparing an initial composite substrate in a method for preparing a light emitting diode epitaxial wafer in an embodiment of the present invention;

[0025] Figure 3 It is a schematic diagram of depositing a gallium nitride layer on a final composite substrate in a method for preparing a light-emitting diode epitaxial wafer in an embodiment of the present invention;

[0026] Figure 4 It is a structural schematic diagram of an epitaxial structure in a method for preparing a light emitting diode epitaxial wafer in an embodiment of the present invention;

[0027] Figure 5 A schematic structural diagram of a light emitting diode epitaxial wafer in another embodiment of the present invention;

[0028] Description of main component symbols:

[0029] The first heterogeneous part 100 The first heterogeneous layer 101 Substrate 110 Aluminum Nitride Buffer Layer 120 Aluminum Gallium Nitride Layer 130 The second heterogeneous layer 210 The third heterogeneous layer 220 GaN layer 300 Composite epitaxial layer 400

[0030] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0031] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0032] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0034] See also Figure 1 The method for preparing a light emitting diode epitaxial wafer in an embodiment of the present invention comprises the following steps:

[0035] S10: providing a substrate, and sequentially depositing an aluminum nitride buffer layer and an aluminum gallium nitride layer on the substrate;

[0036] Preferably, see Figure 2 The substrate 110 is a sapphire substrate. The upper surface of the substrate 110 is flat. The aluminum nitride buffer layer 120 and the aluminum gallium nitride layer 130 are deposited on the flat surface of the substrate 110 .

[0037] Specifically, step S10 includes:

[0038] The thickness of the aluminum nitride buffer layer is in the range of

[0039] Preferably, the thickness of the aluminum nitride buffer layer 120 is selected from It can be understood that depositing the aluminum nitride buffer layer 120 on the sapphire substrate is beneficial to improving the surface roughness and enhancing the growth quality of the subsequent epitaxial structure on the surface.

[0040] The thickness of the aluminum gallium nitride layer is in the range of

[0041] Preferably, the thickness of the aluminum gallium nitride layer 130 is selected from The preparation is performed by using a MOCVD (Metal-Organic Chemical Vapor Deposition) process. Furthermore, after the aluminum nitride buffer layer 120 and the aluminum gallium nitride layer 130 are deposited, a high-temperature annealing planarization treatment is performed.

[0042] S20: depositing a first heterogeneous layer on the aluminum gallium nitride layer, wherein the aluminum nitride buffer layer, the aluminum gallium nitride layer and the first heterogeneous layer are combined to form a substrate composite layer, and the thickness of the first heterogeneous layer is in the range of

[0043]

[0044] Preferably, the material of the first heterogeneous layer 101 can be made of high-transparent and low-refractive index dielectric materials such as silicon oxide, magnesium fluoride, silicon nitride, etc. The preparation process can be made of PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) or chemical vapor deposition. Preferably, the first heterogeneous layer 101 in this embodiment can be made of silicon oxide, and PECVD (Plasma Enhance Chemical Vapor Deposition) technology, with a thickness of After the deposition of the first heterogeneous layer 101 is completed, the first heterogeneous layer 101 is planarized.

[0045] S30: etching a portion of the substrate composite layer until the substrate is exposed, wherein the etched substrate composite layer forms a plurality of substrate composite parts, wherein the substrate composite parts include a plurality of first heterogeneous parts formed by the etched first heterogeneous layer, and the plurality of substrate composite parts and the substrate are combined to form an initial composite substrate;

[0046] Preferably, see Figure 2, in order to prepare a periodic mask to prepare a periodic structure, photoresist or nanoimprint glue can be spin-coated or sprayed on the first heterogeneous layer 101, with one or more layers. In this embodiment, a layer of photoresist is covered by spin-coating. The photoresist layer is turned into a photoresist mask layer through pattern transfer technology, with a periodic pattern on it, and dry etched according to the periodic pattern, until the substrate 110 faces one side of the aluminum nitride buffer layer 120, several substrate composite parts are arranged periodically, the shape of the substrate composite part is axially symmetrical, and has a slope. Specifically, the shape of the substrate composite part is conical. It can be understood that the initial composite substrate has a raised periodic structure, which is different from the refractive index of the epitaxial layer, which easily changes the angle of the emitted light, which is beneficial to improving the light output efficiency of the light emitting diode epitaxial sheet.

[0047] Specifically, the step S30 includes:

[0048] The first heterogeneous portion is cone-shaped.

[0049] Preferably, the first heterogeneous portion 100 is located at the top of the composite portion of the substrate, and the first heterogeneous portion 100 is conical. The refractive index of the first heterogeneous portion is quite different from the refractive index of the common epitaxial layer material. The combination of the two forms a patterned composite epitaxial, which can change the light angle in the light emitting diode, thereby greatly improving the external quantum efficiency and benefiting to improve the light efficiency of the light emitting diode product.

[0050] S40: sequentially depositing a second heterogeneous layer and a third heterogeneous layer on the initial composite substrate to form a final composite substrate;

[0051] See also Figure 3 , if gallium nitride epitaxial is grown on the upper surface of the initial composite substrate, it is easy to cause lattice mismatch and other negative effects on epitaxial growth quality. When the sapphire substrate is peeled off, it is easy to cause damage to the epitaxial layer that directly contacts the sapphire substrate; through the second hetero layer 210 and the third hetero layer 220, it is beneficial to improve the epitaxial growth quality and reduce lattice mismatch. When the sapphire substrate is peeled off, if hidden cracks or peeling surfaces occur, it will only affect the second hetero layer 210 and even the third hetero layer 220. The second hetero layer 210 and the third hetero layer 220 effectively protect the epitaxial layer and improve the quality of the epitaxial layer after the epitaxial layer is peeled off.

[0052] Specifically, the step S40 includes:

[0053] The material of the second heterogeneous layer is aluminum nitride, and the thickness of the second heterogeneous layer is in the range of The material of the third heterogeneous layer is aluminum gallium nitride, and the thickness of the third heterogeneous layer is equal to the thickness of the aluminum gallium nitride layer.

[0054] Preferably, the second heterogeneous layer 210 and the third heterogeneous layer 220 are both subjected to a planarization treatment by high temperature annealing, and aluminum nitride is used as a buffer layer for growing subsequent structures. The thickness of the second heterogeneous layer 210 is selected from The thickness of the third heterogeneous layer 220 is The second heterogeneous layer 210 and the third heterogeneous layer 220 are both prepared by MOCVD process. It can be understood that aluminum nitride as a buffer layer can improve the surface roughness, so that the structure grown on the aluminum nitride in the subsequent preparation process is smoother. Further, the aluminum gallium nitride layer 130 and the third heterogeneous layer 220 both have the characteristic of smooth surface.

[0055] S50: depositing a gallium nitride layer, an N-type gallium nitride layer, a light-emitting layer, and a P-type gallium nitride layer on the final composite substrate in sequence to form an epitaxial structure, wherein a top surface height of the gallium nitride layer is lower than a top height of the first heterogeneous portion;

[0056] Preferably, see Figure 3 Since the top surface height of the gallium nitride layer 300 is lower than the top height of the first heterogeneous part 100, it is equivalent to that the gallium nitride layer 300 is only distributed in the gaps between the plurality of substrate composite parts, and a gallium nitride buffer layer with a periodic pattern is naturally deposited without graphic processing, see Figure 4 The N-type gallium nitride layer, the light emitting layer and the P-type gallium nitride layer form a composite epitaxial layer 400, and the composite epitaxial layer 400 covers the final composite substrate and the gallium nitride layer 300. The N-type gallium nitride layer undergoes homogeneous growth on the basis of the gallium nitride layer 300, which weakens the abnormal influence of the patterned bottom morphology and is beneficial to improving crystal quality. Further, the aluminum gallium nitride of the third hetero layer 220 has the dual advantages of aluminum nitride and gallium nitride. When the flat buffer layer used for epitaxial growth is thick, the problem of insufficient epitaxial recrystallization is prone to occur. The N-type gallium nitride layer can also grow along a partial slope of the aluminum gallium nitride material of the third hetero layer 220 during the deposition process, and the growth quality of the epitaxial layer is excellent.

[0057] Specifically, the step S50 includes:

[0058] The thickness of the gallium nitride layer is in the range of

[0059] Preferably, the thickness of the gallium nitride layer 300 is selected from The gallium nitride layer 300 has a high breakdown voltage, low sensitivity to ionizing radiation, and high thermal conductivity, which is beneficial for stable operation in a high temperature environment.

[0060] S60: peeling off the substrate to form a composite epitaxial wafer, and etching one end of the composite epitaxial wafer facing away from the P-type gallium nitride layer with a sodium hydroxide solution until the etching reaches the gallium nitride layer to form a light-emitting diode epitaxial wafer.

[0061] Preferably, the composite epitaxial sheet is peeled off from the sapphire substrate by laser peeling. The laser peeling is to focus a high-energy laser on the interface between the substrate and the composite epitaxial sheet, and gradually scan the melted part of the composite epitaxial sheet by laser, so as to separate the substrate 110 from the composite epitaxial sheet. After laser peeling, the composite epitaxial sheet is immersed in the high concentration of the sodium hydroxide solution, and both aluminum nitride and aluminum gallium nitride and the sodium hydroxide solution react rapidly. , while the reaction between gallium nitride material and the sodium hydroxide solution is slow, and the corrosion rate difference between aluminum gallium nitride and gallium nitride in the sodium hydroxide solution is large. Therefore, chemical corrosion can be used to remove the bottom aluminum nitride and aluminum gallium nitride in the process of preparing the light emitting diode epitaxial sheet, and prevent the physical structure from cracking. The composite epitaxial sheet is turned off when corrosion to the one end of the P-type gallium nitride layer 300, and the formed light emitting diode epitaxial sheet is removed. If the top surface height of the third hetero layer 220 is greater than the top surface height of the aluminum gallium nitride layer 130, since the sodium hydroxide solution still has a corrosive effect on the silicon oxide material of the first hetero block 100, the light emitting diode epitaxial sheet with a flat bottom can still be obtained through chemical soaking; if the top surface height of the third hetero layer 220 is less than the top surface height of the aluminum gallium nitride 130 layer, when the sodium hydroxide solution corrodes to the gallium nitride layer 300, part of the aluminum gallium nitride layer 130 is still connected to the bottom of the first hetero portion 100, and the remaining part of the aluminum gallium nitride layer 130 is a common bottom surface with the gallium nitride layer 300 after chemical soaking. Since the aluminum gallium nitride layer 130 grows on the flat surface of the aluminum nitride buffer layer 120, it also has a good flatness.

[0062] It can be understood that the bottom of the light emitting diode epitaxial sheet has a complete patterned structure, wherein the first heterogeneous portion 100, part of the second heterogeneous layer 210, and part of the third heterogeneous layer 220 have a refractive index difference and the composite epitaxial layer, which can improve the light output efficiency. When the substrate 110 is peeled off, under the protection of the second heterogeneous layer 210 and the third heterogeneous layer 220, it does not affect the gallium nitride layer 300 and the composite epitaxial layer 400, and the peeling quality is greatly improved.

[0063] See also Figure 5, In some embodiments, the present invention also provides a light emitting diode epitaxial sheet prepared by the light emitting diode epitaxial sheet preparation method in the above-mentioned embodiment. Preferably, the light emitting diode epitaxial sheet includes an epitaxial structure, several first heterogeneous parts 100, several second heterogeneous layers 210 and several third heterogeneous layers 220, the second heterogeneous layer 210 covers the top surface of the first heterogeneous part 100, the third heterogeneous layer 220 covers a side facing the first heterogeneous part 100, the third heterogeneous layer 220, the second heterogeneous layer 210 and the first heterogeneous part 100 are all one-to-one, and the epitaxial structure covers a side facing the third heterogeneous layer 220 against the second heterogeneous layer 210, and the epitaxial structure includes a bottom-up gallium nitride layer 300, an N-type gallium nitride layer, a light emitting layer and a P-type gallium nitride layer, and the top height of the gallium nitride layer 300 is lower than the top height of the first heterogeneous part 100.

[0064] Specifically, the substrate used for the light-emitting diode epitaxial wafer is a sapphire substrate, the bottoms of the epitaxial structure, the plurality of the first heterogeneous parts 100, the plurality of the second heterogeneous layers 210 and the plurality of the third heterogeneous layers 220 all share a bottom surface, the material of the first heterogeneous part 100 is silicon oxide, and the height range is The thickness of the second heterogeneous layer 210 is in the range of The thickness of the third heterogeneous layer 220 is in the range of Furthermore, the height of the first heterogeneous portion 100 is selected from The thickness of the second heterogeneous layer 210 is selected from The thickness of the third heterogeneous layer 220 is selected from The shape of the first heterogeneous portion 100 is conical, and several first heterogeneous portions 100 form periodic arrangements. Several periodic arrangements are distributed on the gallium nitride layer 300. The through holes correspond to the first heterogeneous portion 100 so that the first heterogeneous portion 100 passes through the gallium nitride layer 300 to form a patterned epitaxial buffer layer in combination with the second heterogeneous layer 210 and the third heterogeneous layer 220. The N-type gallium nitride layer, the light emitting layer and the P-type gallium nitride layer form a composite epitaxial layer 400. It can be understood that the bottom of the light emitting diode epitaxial sheet is provided with a heterogeneous periodic microstructure, wherein the silicon oxide of the first heterogeneous portion 100 has the characteristics of high transparency and low refractive index, and the difference in refractive index between the composite epitaxial layer 400 is beneficial to changing the light output angle and improving the light output efficiency.

[0065] Further, during the preparation process of the light emitting diode epitaxial sheet, when the composite epitaxial layer 400 is deposited, the gallium nitride layer 300 is located at the bottom, and the third heterogeneous layer 220 is located on the side of the area to be deposited. During the deposition process, the grown composite epitaxial layer 400 has a high quality. After the multi-layer semiconductor structure is prepared, the substrate is peeled off and the high concentration sodium hydroxide solution is soaked to expose the gallium nitride layer 300, removing the excess structure, and causing little damage to the bottom of the light emitting diode epitaxial sheet, avoiding the phenomenon that traditional laser peeling is prone to cause hidden cracks or other damage on the peeling surface, so that high epitaxial quality and high luminous efficiency are both present.

[0066] In some embodiments, the present invention further provides a device, which includes the light-emitting diode epitaxial wafer as described in the above embodiments.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0068] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a light emitting diode epitaxial wafer, characterized in that: The steps include: Providing a substrate, and sequentially depositing an aluminum nitride buffer layer and an aluminum gallium nitride layer on the substrate; A first heterogeneous layer is deposited on the aluminum gallium nitride layer. The aluminum nitride buffer layer, the aluminum gallium nitride layer and the first heterogeneous layer are combined to form a substrate composite layer. The thickness of the first heterogeneous layer is in the range of Etching part of the substrate composite layer until the substrate is exposed, the etched substrate composite layer forms a plurality of substrate composite parts, the substrate composite parts include a plurality of first heterogeneous parts formed by the etched first heterogeneous layer, and the plurality of substrate composite parts and the substrate are combined to form an initial composite substrate; Depositing a second heterogeneous layer and a third heterogeneous layer in sequence on the initial composite substrate to form a final composite substrate; Depositing a gallium nitride layer, an N-type gallium nitride layer, a light-emitting layer, and a P-type gallium nitride layer on the final composite substrate in sequence to form an epitaxial structure, wherein a top surface height of the gallium nitride layer is lower than a top height of the first heterogeneous portion; The substrate is peeled off to form a composite epitaxial wafer, and a sodium hydroxide solution is used to etch one end of the composite epitaxial wafer facing away from the P-type gallium nitride layer until the etching reaches the gallium nitride layer to form a light-emitting diode epitaxial wafer.

2. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the aluminum nitride buffer layer is in the range of 3. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the aluminum gallium nitride layer is in the range of 4. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The material of the second heterogeneous layer is aluminum nitride, and the thickness of the second heterogeneous layer is in the range of The material of the third heterogeneous layer is aluminum gallium nitride, and the thickness of the third heterogeneous layer is equal to the thickness of the aluminum gallium nitride layer.

5. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The thickness of the gallium nitride layer is in the range of 6. The method for preparing a light emitting diode epitaxial wafer according to claim 1, characterized in that: The first heterogeneous portion is cone-shaped.

7. A light emitting diode epitaxial wafer, characterized in that: The light emitting diode is prepared by the light emitting diode preparation method according to any one of claims 1 to 6.

8. A device, characterized in that: Comprising the light emitting diode epitaxial wafer as claimed in claim 7.

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