LED epitaxial wafer, epitaxial growth method and LED chip

Abstract

The application provides an LED epitaxial wafer, an epitaxial growth method and an LED chip, the LED epitaxial wafer comprises an electron blocking layer and a P-type GaN layer, the P-type GaN layer comprises a P-type GaN atmosphere transition layer, an undoped P-type GaN layer and an Mg-doped P-type GaN layer, and is sequentially stacked on the electron blocking layer, the thickness of the undoped P-type GaN layer is 1-1.5 times the thickness of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5-2 times the thickness of the P-type GaN atmosphere transition layer, wherein the P-type GaN atmosphere transition layer is deposited under the condition of atmosphere gradual change, and the undoped P-type GaN layer and the Mg-doped P-type GaN layer are deposited under a stable N2 / H2 / NH3 atmosphere. The application can effectively solve the problem that the P-type nitride layer has weak V-pit filling ability in the existing GaN-based LED epitaxial structure.

Description

Technical Field

[0001] This invention relates to the field of LED technology, and in particular to an LED epitaxial wafer, an epitaxial growth method, and an LED chip. Background Technology

[0002] Light-emitting diodes (LEDs) are semiconductor electronic components that emit light. Due to their small size, high brightness, and low power consumption, they have attracted increasing attention from researchers. Among them, GaN-based LEDs have advantages such as high density, low power consumption, long lifespan, short response time, and no radiation, and are widely used in lighting and display fields.

[0003] Currently, the traditional epitaxial structure of GaN-based LEDs involves sequentially depositing a buffer layer, an undoped nitride layer, an N-type nitride layer, a stress relief layer, a multiple quantum well layer, an electron blocking layer, a P-type GaN layer, and a P-type contact layer on a substrate. The P-type nitride layer is primarily grown in a high-H2 atmosphere with a high concentration of Mg-doped GaN. Throughout the growth process, a high Mg concentration is maintained within the reaction chamber to increase the activation Mg concentration of the P-type GaN layer. However, this growth method has several drawbacks. Firstly, the P-type nitride layer has a weak ability to fill V-pits, typically requiring additional processing time. First, a relatively thick p-type nitride layer is needed to fill the V-pits. Second, during the growth process in MOCVD, a large number of H atoms are present. When the growth temperature is high, the ability of H ions to form is lower than that of nitrogen vacancies (VN). Therefore, Mg is passivated by H ions, resulting in a low concentration of activated Mg in the p-type nitride. Third, when the Mg doping concentration is very high, Mg atoms and N atoms form Mg3N2 complexes, which will produce a serious self-compensation effect and greatly reduce the activation rate of Mg. Fourth, the energy level of Mg acceptors is relatively deep, about 170 meV, and the ionization rate of Mg at room temperature is only about 1%. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide an LED epitaxial wafer, an epitaxial growth method, and an LED chip, aiming to solve the problem that the P-type nitride layer has a weak ability to fill V-pits in existing GaN-based LED epitaxial structures.

[0005] An LED epitaxial wafer according to an embodiment of the present invention includes an electron blocking layer and a P-type GaN layer. The P-type GaN layer includes a P-type GaN atmosphere transition layer, an undoped P-type GaN layer, and a Mg-doped P-type GaN layer, which are sequentially stacked on the electron blocking layer. The thickness of the undoped P-type GaN layer is 1 to 1.5 times the thickness of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5 to 2 times the thickness of the P-type GaN atmosphere transition layer. The P-type GaN atmosphere transition layer is deposited in an atmosphere that gradually changes from the N2 / NH3 atmosphere of the electron blocking layer to an N2 / H2 / NH3 atmosphere. The undoped P-type GaN layer and the Mg-doped P-type GaN layer are deposited in a stable N2 / H2 / NH3 atmosphere.

[0006] Preferably, the LED epitaxial wafer further includes a patterned substrate, a buffer layer, an unintentionally doped GaN layer, an N-type GaN layer, a multiple quantum well layer, and a P-type contact layer;

[0007] The buffer layer, the unintentionally doped GaN layer, the N-type GaN layer, the multiple quantum well layer, the electron blocking layer, the P-type GaN layer, and the P-type contact layer are sequentially epitaxially grown on the patterned substrate.

[0008] Preferably, the thickness of the P-type GaN layer is 5 nm to 100 nm, the thickness of the buffer layer is 10 nm to 30 nm, the thickness of the unintentionally doped GaN layer is 2 μm to 3 μm, the thickness of the N-type GaN layer is 2 μm to 3 μm, the thickness of the multiple quantum well layer is 11 nm to 15.5 nm, the thickness of the electron blocking layer is 10 nm to 40 nm, and the thickness of the P-type contact layer is 1 nm to 5 nm.

[0009] Preferably, the multiple quantum well layer is an alternating stack of InGaN quantum well layers and AlGaN quantum barrier layers, with a stacking period of 6 to 12.

[0010] According to an embodiment of the present invention, an epitaxial growth method for LED epitaxial wafers is used to prepare the aforementioned LED epitaxial wafers. The epitaxial growth method includes:

[0011] Provide an electron blocking layer;

[0012] A P-type GaN layer is deposited on the electron blocking layer;

[0013] The P-type GaN layer comprises a P-type GaN atmosphere transition layer, an undoped P-type GaN layer, and a Mg-doped P-type GaN layer, which are sequentially stacked on the electron blocking layer. The P-type GaN atmosphere transition layer is deposited under an atmosphere that gradually changes from the N2 / NH3 atmosphere of the electron blocking layer to an N2 / H2 / NH3 atmosphere. The undoped P-type GaN layer and the Mg-doped P-type GaN layer are deposited under a stable N2 / H2 / NH3 atmosphere. The thickness of the undoped P-type GaN layer is 1 to 1.5 times the thickness of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5 to 2 times the thickness of the P-type GaN atmosphere transition layer.

[0014] Preferably, the epitaxial growth method further includes:

[0015] Provide a patterned substrate required for growth;

[0016] A buffer layer, an unintentionally doped GaN layer, an N-type GaN layer, a multiple quantum well layer, the electron blocking layer, the P-type GaN layer, and a P-type contact layer are epitaxially grown sequentially on the patterned substrate.

[0017] Preferably, the ratio of each gas in the N2 / H2 / NH3 atmosphere is 1:5:10 to 1:10:20.

[0018] Preferably, the growth temperature of the P-type GaN layer is 950℃~1000℃, and the growth pressure is 100~600 torr.

[0019] Preferably, the unintentionally doped GaN layer is grown at a temperature of 1100°C and a pressure of 100–600 torr.

[0020] An LED chip according to an embodiment of the present invention includes the above-described LED epitaxial wafer.

[0021] Compared with existing technologies: By sequentially stacking a P-type GaN atmosphere transition layer, an undoped P-type GaN layer, and a Mg-doped P-type GaN layer on an electron blocking layer, and introducing H2 during the deposition of the P-type GaN atmosphere transition layer to change the electron blocking layer atmosphere from N2 / NH3 to N2 / H2 / NH3, the growth atmosphere transition time is reduced. Introducing H2 at this stage can improve the crystal quality of the P-type GaN atmosphere transition layer. Furthermore, by sequentially depositing an undoped P-type GaN layer and a Mg-doped P-type GaN layer on the P-type GaN atmosphere transition layer... In the N-layer, since neither the P-type GaN atmosphere transition layer nor the undoped P-type GaN layer is doped with Mg, the possibility of light absorption and reduced luminous efficiency due to excessive Mg doping is reduced. Specifically, the thickness of the undoped P-type GaN layer is 1 to 1.5 times that of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5 to 2 times that of the P-type GaN atmosphere transition layer. With this thickness ratio, V-pits can be filled more effectively, and the thickness of the P-type GaN layer is reduced, thereby improving the light extraction efficiency of the LED. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the LED epitaxial wafer in Embodiment 1 of the present invention;

[0023] Figure 2 This is a schematic diagram of the structure of the P-type GaN layer in the LED epitaxial wafer according to Embodiment 1 of the present invention;

[0024] Figure 3 This is a flowchart of the epitaxial growth method for LED epitaxial wafers in Embodiment 2 of the present invention.

[0025] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0026] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0027] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Example 1

[0030] Please see Figure 1 and Figure 2 The image shows an LED epitaxial wafer in Embodiment 1 of the present invention, including a patterned substrate 10 and a buffer layer 20, an unintentionally doped GaN layer 30, an N-type GaN layer 40, a multiple quantum well layer 50, an electron blocking layer 60, a P-type GaN layer 70, and a P-type contact layer 80, which are epitaxially grown sequentially on the patterned substrate.

[0031] In this embodiment, the patterned substrate is a sapphire substrate. The P-type GaN layer 70 includes a P-type GaN atmosphere transition layer 701, an undoped P-type GaN layer 702, and a Mg-doped P-type GaN layer 703, which are sequentially stacked on the electron blocking layer 60. It should be noted that the epitaxial wafer is grown using A7 MOCVD (Metal-organic Chemical Vapor Deposition). The process is achieved in a MOCVD (Metal-Oxide-Chip Deposition) device, using one of the following as the carrier gas: high-purity H2 (hydrogen), high-purity N2 (nitrogen), or a mixture of high-purity H2 and high-purity N2. High-purity NH3 is used as the N source. Understandably, during the growth of the electron blocking layer, the environment contains a mixture of high-purity N2 and high-purity NH3. When the P-type GaN atmosphere transition layer 701 begins to grow, the ambient atmosphere gradually changes from an N2 / NH3 atmosphere to an N2 / H2 / NH3 atmosphere, that is, H2 is introduced into the growth environment. When the H2 concentration reaches a certain level, the introduction is stopped. In addition, the undoped P-type GaN layer 702 and the Mg-doped P-type GaN layer 703 are sequentially deposited on the P-type GaN atmosphere transition layer 701 under a stable N2 / H2 / NH3 atmosphere.

[0032] By way of example and not limitation, in some preferred embodiments of this embodiment, the thickness of the undoped P-type GaN layer 702 is 1 to 1.5 times the thickness of the P-type GaN atmosphere transition layer 701, for example, 1, 1.3, 1.5 times, etc.; the thickness of the Mg-doped P-type GaN layer 703 is 1.5 to 2 times the thickness of the P-type GaN atmosphere transition layer 701, for example, 1.5, 1.7, 2 times, etc.

[0033] By way of example and not limitation, in some preferred embodiments of this embodiment, the thickness of the P-type GaN layer 70 is 5nm to 100nm, for example, 10nm, 15nm, 20nm, etc.; the thickness of the buffer layer 20 is 10nm to 30nm, for example, 10nm, 15nm, 20nm, etc.; the thickness of the unintentionally doped GaN layer 30 is 2um to 3um, for example, 2um, 2.5um, 3um, etc.; the thickness of the N-type GaN layer 40 is 2um to 3um, for example, 2um, 2.5um, 3um, etc.; the thickness of the multiple quantum well layer 50 is 11nm to 15.5nm, for example, 11nm, 13nm, 15nm, etc.; the thickness of the electron blocking layer 60 is 10 to 40nm, for example, 10nm, 20nm, 30nm, etc.; and the thickness of the P-type contact layer 80 is 1nm to 5nm, for example, 2nm, 3nm, 4nm, etc. The multi-quantum well layer 50 consists of alternating stacked InGaN quantum well layers and AlGaN quantum barrier layers, with a stacking period of 6 to 12, such as 6, 8, or 10. It should be noted that the thickness of the InGaN quantum well layer is 2 nm to 3.5 nm, such as 2 nm, 2.5 nm, or 3 nm, and the thickness of the AlGaN quantum barrier layer is 9 nm to 12 nm, such as 9 nm, 10.5 nm, or 12 nm.

[0034] Example 2

[0035] Please see Figure 3 The figure shows an epitaxial growth method for an LED epitaxial wafer according to Embodiment 2 of the present invention, used to prepare the LED epitaxial wafer in Embodiment 1 above. The method specifically includes steps S201 to S208, wherein:

[0036] Step S201: Provide a patterned substrate required for growth.

[0037] Specifically, the patterned substrate is a sapphire substrate. However, this is not a limitation. In some preferred embodiments of this example, the patterned substrate may also be a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, a zinc oxide substrate, etc.

[0038] Step S202: Grow a buffer layer with a thickness of 10 nm to 30 nm.

[0039] In this embodiment, the buffer layer is AlN, which is deposited in a PVD (physical vapor deposition) system with a deposition thickness of 15 nm.

[0040] Step S203: Grow an unintentionally doped GaN layer with a thickness of 2µm to 3µm.

[0041] The patterned substrate is a sapphire substrate with an AlN buffer layer deposited on it. It is placed on a graphite tray and sent into the reaction chamber for epitaxial material growth. The growth temperature of the unintentionally doped GaN layer is 1100℃ and the pressure is 100-600 torr.

[0042] It should be noted that the growth of the LED epitaxial wafer was achieved using an AMEC A7 MOCVD (Metal-organic Chemical Vapor Deposition, or MOCVD) system. A sapphire substrate with an AlN buffer layer was placed in the MOCVD chamber. One of the following gases was used as the carrier gas: high-purity H2 (hydrogen), high-purity N2 (nitrogen), or a mixture of high-purity H2 and high-purity N2. High-purity NH3 was used as the N-type source, trimethylgallium (TMGa) and triethylgallium (TEGa) as gallium sources, trimethylindium (TMIn) as the indium source, trimethylaluminum (TMAl) as the aluminum source, silane (SiH4) as the N-type dopant, and magnesium diacene (CP2Mg) as the P-type dopant for epitaxial growth.

[0043] Step S204: Grow an N-type GaN layer with a thickness of 2µm to 3µm.

[0044] Specifically, the growth temperature of the N-type GaN layer is 1100℃, and the Si doping concentration is 1.6E19.

[0045] Step S205: Grow a multi-quantum well layer with a thickness of 11 nm to 15.5 nm.

[0046] In this embodiment, the quantum well light-emitting layer is an alternating stack of InGaN quantum well layers and AlGaN quantum barrier layers, wherein the growth temperature of the InGaN quantum well layer is 790℃~810℃ and the growth temperature of the AlGaN quantum barrier layer is 850℃~9000℃.

[0047] Step S206: Grow an electron blocking layer with a thickness of 10 nm to 40 nm.

[0048] Specifically, the electron blocking layer is AlInGaN, and its growth temperature is 900℃-1000℃.

[0049] Step S207: Grow a P-type GaN layer with a thickness of 5 nm to 100 nm.

[0050] It should be noted that the P-type GaN layer includes a P-type GaN atmosphere transition layer, an undoped P-type GaN layer, and a Mg-doped P-type GaN layer, sequentially stacked on an electron blocking layer AlInGaN. Neither the P-type GaN atmosphere transition layer nor the undoped P-type GaN layer is Mg-doped, while the Mg-doped P-type GaN layer is heavily Mg-doped. The atmosphere of the P-type GaN atmosphere transition layer gradually changes from the N2 / NH3 atmosphere of the electron blocking layer to an N2 / H2 / NH3 atmosphere, while the undoped P-type GaN layer and the Mg-doped P-type GaN layer are deposited in a stable N2 / H2 / NH3 atmosphere. The final thickness of the undoped P-type GaN layer is 1 to 1.5 times that of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5 to 2 times that of the P-type GaN atmosphere transition layer. It is worth noting that while a thicker P-type GaN layer can better fill V-pits, excessive thickness can lead to absorption of light emitted by the LED, thus reducing luminous efficiency.

[0051] Understandably, H2 is introduced during the growth of the P-type GaN atmosphere transition layer, gradually changing the N2 / NH3 atmosphere of the electron blocking layer to an N2 / H2 / NH3 atmosphere. The ratio of each gas in the N2 / H2 / NH3 atmosphere is 1:5:10 to 1:10:20. This is an example and not a limitation. In some preferred embodiments of this example, when the N2 / H2 / NH3 atmosphere ratio is 1:6:15, better crystal quality can be obtained under this atmosphere condition.

[0052] In this embodiment, the thickness of the p-type GaN layer is 15 nm, and the Mg concentration is greater than 1E19. The thickness of the undoped p-type GaN layer is 1.3 times the thickness of the p-type GaN atmosphere transition layer, and the thickness of the Mg-doped p-type GaN layer is 1.5 times the thickness of the p-type GaN atmosphere transition layer. This effectively fills the V-Pits, reduces the thickness of the Mg-doped p-type GaN layer, and increases the active Mg concentration of the p-type GaN layer.

[0053] Specifically, the growth temperature of the P-type GaN layer is 950℃~1000℃, and the growth pressure is 100~600 torr. In this embodiment, the growth temperature of the P-type GaN layer is 980℃, and the growth pressure is 200 torr. Growing the P-type GaN layer at a higher temperature and lower pressure improves the atomic mobility and enhances the ability of GaN to fill V-Pits.

[0054] Step S208: Grow a P-type contact layer with a thickness of 1 nm to 5 nm.

[0055] The P-type contact layer is a heavily Mg-doped GaN layer, and the growth temperature is 800℃~900℃.

[0056] In summary, the LED epitaxial wafer and its epitaxial growth method in the embodiments of the present invention involve sequentially stacking a P-type GaN atmosphere transition layer, an undoped P-type GaN layer, and a Mg-doped P-type GaN layer on an electron blocking layer. During the deposition of the P-type GaN atmosphere transition layer, H2 is introduced to change the atmosphere from N2 / NH3 to N2 / H2 / NH3, thereby reducing the growth atmosphere transition time. Introducing H2 at this stage can improve the crystal quality of the P-type GaN atmosphere transition layer. Furthermore, undoped P-type GaN layers are sequentially deposited on the P-type GaN atmosphere transition layer. The Mg-doped P-type GaN layer and the Mg-doped P-type GaN layer are designed to reduce the possibility of light absorption and reduced luminous efficiency caused by excessive Mg doping, since neither the P-type GaN atmosphere transition layer nor the undoped P-type GaN layer is doped with Mg. Specifically, the thickness of the undoped P-type GaN layer is 1-1.5 times that of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5-2 times that of the P-type GaN atmosphere transition layer. With this thickness ratio, V-pits can be filled more effectively, and the thickness of the P-type GaN layer is reduced, thereby improving the light extraction efficiency of the LED.

[0057] Example 3

[0058] Embodiment 3 of the present invention provides an LED chip, including the LED epitaxial wafer in Embodiment 1 above. The LED epitaxial wafer can be epitaxially grown by the epitaxial growth method of the LED epitaxial wafer in Embodiment 2 above.

[0059] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An LED epitaxial wafer, characterized in that, The P-type GaN layer includes a P-type GaN atmosphere transition layer, a non-doped P-type GaN layer, and a Mg-doped P-type GaN layer, which are sequentially stacked on the electron blocking layer, the thickness of the non-doped P-type GaN layer is 1-1.5 times the thickness of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5-2 times the thickness of the P-type GaN atmosphere transition layer, wherein the P-type GaN atmosphere transition layer is deposited in the case that the atmosphere gradually changes from the N2 / NH3 atmosphere of the electron blocking layer to the N2 / H2 / NH3 atmosphere, the non-doped P-type GaN layer and the Mg-doped P-type GaN layer are deposited in the stable N2 / H2 / NH3 atmosphere, neither the P-type GaN atmosphere transition layer nor the non-doped P-type GaN layer is doped with Mg, the ratio of the N2 / H2 / NH3 atmosphere is 1:6:15, the thickness of the P-type GaN layer is 15 nm, the Mg concentration is greater than 1E19, the thickness of the non-doped P-type GaN layer is 1.3 times the thickness of the P-type GaN atmosphere transition layer, and the thickness of the Mg-doped P-type GaN layer is 1.5 times the thickness of the P-type GaN atmosphere transition layer.

2. The LED epitaxial wafer of claim 1, wherein, The LED epitaxial wafer further includes a patterned substrate, a buffer layer, a non-intentionally doped GaN layer, an N-type GaN layer, a multi-quantum well layer, and a P-type contact layer. The buffer layer, the non-intentionally doped GaN layer, the N-type GaN layer, the multi-quantum well layer, the electron blocking layer, the P-type GaN layer, and the P-type contact layer are sequentially epitaxially grown on the patterned substrate.

3. The LED epitaxial wafer of claim 2, wherein, The thickness of the P-type GaN layer is 5-100 nm, the thickness of the buffer layer is 10-30 nm, the thickness of the non-intentionally doped GaN layer is 2-3 um, the thickness of the N-type GaN layer is 2-3 um, the thickness of the multi-quantum well layer is 11-15.5 nm, the thickness of the electron blocking layer is 10-40 nm, and the thickness of the P-type contact layer is 1-5 nm.

4. The LED epitaxial wafer of claim 2, wherein, The multi-quantum well layer is an InGaN quantum well layer and an AlGaN quantum barrier layer which are alternately stacked, and the number of stacking periods is 6-12.

5. An epitaxial growth method of an LED epitaxial wafer, characterized by, The epitaxial growth method for preparing the LED epitaxial wafer of any one of claims 1-4 comprises: providing an electron blocking layer; depositing a P-type GaN layer on the electron blocking layer; The P-type GaN layer comprises a P-type GaN atmosphere transition layer, an undoped P-type GaN layer, and a Mg-doped P-type GaN layer, which are sequentially stacked on the electron blocking layer, wherein the P-type GaN atmosphere transition layer is deposited in a case where the atmosphere gradually changes from the N2 / NH3 atmosphere of the electron blocking layer to an N2 / H2 / NH3 atmosphere, the undoped P-type GaN layer and the Mg-doped P-type GaN layer are deposited in the stable N2 / H2 / NH3 atmosphere, the thickness of the undoped P-type GaN layer is 1-1.5 times the thickness of the P-type GaN atmosphere transition layer, the thickness of the Mg-doped P-type GaN layer is 1.5-2 times the thickness of the P-type GaN atmosphere transition layer, and neither the P-type GaN atmosphere transition layer nor the undoped P-type GaN layer is doped with Mg.

6. The method of epitaxial growth of an LED epiwafer of claim 5, wherein, The epitaxial growth method further comprises: providing a patterned substrate required for growth; sequentially epitaxially growing a buffer layer, an unintentionally doped GaN layer, an N-type GaN layer, a multi-quantum well layer, the electron blocking layer, the P-type GaN layer, and a P-type contact layer on the patterned substrate.

7. The method of epitaxial growth of LED epiwafers according to claim 5, wherein, The ratio of each gas in the N2 / H2 / NH3 atmosphere is 1:5:10-1:10:

20.

8. The method of epitaxial growth of LED epiwafers according to claim 5, wherein, The growth temperature of the P-type GaN layer is 950-1000°C, and the growth pressure is 100-600 torr.

9. The method of epitaxial growth of LED epiwafers according to claim 6, wherein, The growth temperature of the unintentionally doped GaN layer is 1100°C, and the pressure is 100-600 torr.

10. An LED chip, characterized by An LED epitaxial wafer comprising any one of claims 1-4. An LED epitaxial wafer comprising any one of claims 1-4.

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