An LED epitaxial wafer, an epitaxial growth method, and an LED chip

Abstract

This invention provides an LED epitaxial wafer, an epitaxial growth method, and an LED chip. The LED epitaxial wafer includes a buffer layer, which is composed of an Al / AlN / NH3 superlattice layer and an Al / AlN / H2 superlattice layer deposited on the Al / AlN / NH3 superlattice layer. The Al / AlN / NH3 superlattice layer is a periodic structure formed by the alternating growth of Al, AlN, and NH3 sublayers, and the Al / AlN / H2 superlattice layer is also a periodic structure formed by the alternating growth of Al, AlN, and H2 sublayers. Because the Al / AlN / NH3 superlattice layer is grown in a three-dimensional mode, and the Al / AlN / H2 superlattice layer is grown in a two-dimensional mode, a relatively flat epitaxial layer can be obtained by covering the already grown three-dimensional Al / AlN superlattice layer, thus solving the problem of poor crystal quality in existing ultraviolet light-emitting diodes.

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] Over the past decade, AlGaN materials have attracted much attention due to their enormous application potential in ultraviolet optoelectronic devices. Ultraviolet LEDs have the characteristics of high photon energy, short wavelength, small size, low power consumption, long lifespan, and environmental friendliness, and have wide applications in high color rendering index white light illumination, high-density optical data storage, sensors, offset printing, air purification and environmental protection.

[0003] The development of AlGaN-based ultraviolet LEDs faces numerous technical challenges. First, the relatively low effective mass of electrons and their high mobility mean that many electrons easily overflow into the P-layer through the quantum well. Second, increasing the Al content leads to high defect density and surface unevenness in epitaxially grown AlGaN films, making it difficult to obtain high-quality AlGaN materials. Furthermore, high-Al-content AlGaN materials, whether N-type or P-type doped, are significantly more difficult to develop than GaN materials, especially P-AlGaN doping. Particularly challenging are the low activation efficiency of the dopant Mg, leading to insufficient holes and reduced radiative recombination efficiency; and the upward diffusion of oxygen atoms from the decomposition of oxides on the substrate surface under the high-temperature conditions of epitaxial growth. Since the Al content in the epitaxial layer of a UV LED is high, and Al atoms have a strong adsorption capacity for oxygen atoms, the oxygen content in the epitaxial layer is high, resulting in a high background carrier concentration and a decrease in crystal quality. The luminous efficiency of a UV LED is closely related to its crystal quality; the higher the crystal quality of the UV LED epitaxial layer, the higher its luminous efficiency. Therefore, to improve the photoelectric capability of UV LEDs, it is necessary to fabricate UV LED epitaxial layer structures with high crystal quality.

[0004] Currently, the epitaxial growth of ultraviolet LEDs generally involves first preparing an AlN (or AlGaN) buffer layer using MOCVD, PVD, or a combination of both methods, and then continuing the epitaxial growth of subsequent structures in MOCVD. Although the AlN (or AlGaN) buffer layer can alleviate the lattice mismatch between the substrate and the AlGaN epitaxial layer to some extent and meet the requirements of epitaxial growth, it is far from sufficient for ultraviolet light-emitting diodes (UV LEDs) with higher crystal quality requirements, and further improvements in the crystal quality of epitaxial growth are needed. Summary of the Invention

[0005] 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 of poor crystal quality in existing ultraviolet light-emitting diodes with epitaxial growth.

[0006] According to an embodiment of the present invention, an LED epitaxial wafer includes a buffer layer, the buffer layer being composed of an Al / AlN / NH3 superlattice layer and an Al / AlN / H2 superlattice layer, wherein the Al / AlN / H2 superlattice layer is deposited on the Al / AlN / NH3 superlattice layer;

[0007] The Al / AlN / NH3 superlattice layer is a periodic structure formed by the alternating growth of Al sublayers, AlN sublayers, and NH3 sublayers, and the Al / AlN / H2 superlattice layer is a periodic structure formed by the alternating growth of the Al sublayers, AlN sublayers, and H2 sublayers.

[0008] Preferably, the LED epitaxial wafer further includes a sapphire substrate, an undoped AlGaN layer, an N-type doped AlGaN layer, a multiple quantum well layer, an electron blocking layer, a P-type doped GaN layer, and an AlGaN contact layer;

[0009] The buffer layer, the undoped AlGaN layer, the N-type doped AlGaN layer, the multiple quantum well layer, the electron blocking layer, the P-type doped GaN layer, and the AlGaN contact layer are sequentially epitaxially grown on the sapphire substrate.

[0010] Preferably, the total thickness of the Al / AlN / NH3 superlattice layer is 50nm to 100nm, the thickness of the Al sublayer in a single period is 1nm to 2nm, the thickness of the AlN sublayer in a single period is 5nm to 10nm, the total thickness of the Al / AlN / H2 superlattice layer is 100nm to 200nm, the thickness of the Al sublayer in a single period is 1nm to 2nm, the thickness of the AlN sublayer in a single period is 10nm to 20nm, the thickness of the undoped AlGaN layer is 1μm to 3μm, the thickness of the N-type doped AlGaN layer is 1μm to 3μm, the thickness of the multiple quantum well layer is 50nm to 288nm, the thickness of the electron blocking layer is 20nm to 100nm, the thickness of the P-type doped GaN layer is 30nm to 200nm, and the thickness of the AlGaN contact layer is 10nm to 50nm.

[0011] Preferably, the multiple quantum well layer is a periodic structure formed by alternating growth of AlGaN layers and GaN layers, wherein the GaN layer is a well layer with a thickness of 2nm to 4nm in a single period, and the AlGaN layer is a barrier layer with a thickness of 8nm to 20nm in a single period.

[0012] 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:

[0013] During the growth of the buffer layer, the Al sublayer, AlN sublayer, and NH3 sublayer are controlled to grow alternately in a cycle to form an Al / AlN / NH3 superlattice layer.

[0014] The Al sublayer, AlN sublayer, and H2 sublayer are cyclically and alternately grown on the Al / AlN / NH3 superlattice layer to form an Al / AlN / H2 superlattice layer.

[0015] Preferably, the epitaxial growth method further includes:

[0016] Provide a sapphire substrate required for growth;

[0017] The buffer layer, the undoped AlGaN layer, the N-type doped AlGaN layer, the multiple quantum well layer, the electron blocking layer, the P-type doped GaN layer, and the AlGaN contact layer are epitaxially grown sequentially on the sapphire substrate.

[0018] Preferably, the growth temperature of the Al / AlN / NH3 superlattice layer is 800℃~900℃, the growth pressure is 30torr~80torr, the molar ratio of V / III is between 2000 and 4000, and the NH3 layer is annealed by only introducing NH3 in a single cycle for 5s~10s, without introducing a MO source for growth.

[0019] Preferably, the growth temperature of the Al / AlN / H2 superlattice layer is 1050℃~1200℃, the growth pressure is 30 torr~80 torr, the molar ratio of V / III is between 50 and 500, and the H2 layer is annealed by only introducing H2 in a single cycle for 5s~10s, without introducing a MO source for growth.

[0020] Preferably, the growth temperature of the undoped AlGaN layer is 1050℃-1200℃, the growth pressure is between 50 torr and 100 torr, and the Al composition is between 0.3 and 0.8.

[0021] An LED chip according to an embodiment of the present invention includes the above-described LED epitaxial wafer.

[0022] Compared with existing technologies: By using a buffer layer composed of a low-temperature Al / AlN / NH3 superlattice layer with a high V / III ratio and a high-temperature Al / AlN / H2 superlattice layer with a low V / III ratio, the high-V / III ratio low-temperature Al / AlN / NH3 superlattice layer in the buffer layer grows in a three-dimensional mode, which can effectively annihilate dislocations caused by lattice mismatch between the substrate and the epitaxial layer, and prevent defects from continuing to extend into the epitaxial layer. Then, through NH3 annealing, the epitaxial layer is more inclined to grow in a three-dimensional mode, further reducing dislocations. The low-V / III ratio high-temperature Al / AlN / H2 superlattice layer in the buffer layer grows in a two-dimensional mode. By covering the above-mentioned grown three-dimensional Al / AlN superlattice layer, a relatively flat epitaxial layer can be obtained. Then, through H2 annealing, the surface of the epitaxial layer is made smoother, and the crystal quality is further improved. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the LED epitaxial wafer in Embodiment 1 of the present invention;

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

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Example 1

[0029] Please see Figure 1The image shows an LED epitaxial wafer in Embodiment 1 of the present invention, including a sapphire substrate 1, and a buffer layer 2, an undoped AlGaN layer 3, an N-type doped AlGaN layer 4, a multiple quantum well layer 5, an electron blocking layer 6, a P-type doped GaN layer 7, and an AlGaN contact layer 8 epitaxially grown sequentially on the sapphire substrate 1.

[0030] In this embodiment, the buffer layer 2 is composed of an Al / AlN / NH3 superlattice layer 21 and an Al / AlN / H2 superlattice layer 22, with the Al / AlN / H2 superlattice layer 22 deposited on the Al / AlN / NH3 superlattice layer 21. The Al / AlN / NH3 superlattice layer 21 is a periodic structure formed by the alternating growth of Al sublayers, AlN sublayers, and NH3 sublayers, and the Al / AlN / H2 superlattice layer 22 is a periodic structure formed by the alternating growth of Al sublayers, AlN sublayers, and H2 sublayers.

[0031] As an example, and not a limitation, in some preferred embodiments of this example, the total thickness of the Al / AlN / NH3 superlattice layer 21 is 50nm to 100nm, for example, 60nm, 70nm, 80nm, etc.; the thickness of the Al sublayer within a single period is 1nm to 2nm, for example, 1nm, 1.5nm, 2nm, etc.; the thickness of the AlN sublayer within a single period is 5nm to 10nm, for example, 6nm, 7nm, 8nm, etc.; the total thickness of the Al / AlN / H2 superlattice layer 22 is 100nm to 200nm, for example, 100nm, 120nm, 140nm, etc.; the thickness of the Al sublayer within a single period is 1nm to 2nm, for example, 1nm, 1.5nm, 2nm, etc.; and the thickness of the AlN sublayer within a single period is 10nm to 20nm, for example... For example, the thickness of the undoped AlGaN layer 3 is 1μm to 3μm, such as 1μm, 2μm, 3μm, etc.; the thickness of the N-type doped AlGaN layer 4 is 1μm to 3μm, such as 1μm, 2μm, 3μm, etc.; the thickness of the multiple quantum well layer 5 is 50nm to 288nm, such as 100nm, 150nm, 200nm, etc.; the thickness of the electron blocking layer 6 is 20nm to 100nm, such as 20nm, 40nm, 60nm, etc.; the thickness of the P-type doped GaN layer 7 is 30nm to 200nm, such as 40nm, 60nm, 80nm, etc.; and the thickness of the AlGaN contact layer 8 is 10nm to 50nm, such as 20nm, 30nm, 40nm, etc. In the Al / AlN / NH3 superlattice layer 21, the Al sublayer, AlN sublayer, and NH3 sublayer grow in alternating cycles of 3 to 10 times, for example, 5 times, meaning that a total of 5 Al / AlN / NH3 superlattice layers 21 are grown. Similarly, in the Al / AlN / H2 superlattice layer 22, the Al sublayer, AlN sublayer, and H2 sublayer grow in alternating cycles of 3 to 10 times, for example, 5 times, meaning that a total of 5 Al / AlN / H2 superlattice layers 22 are grown.

[0032] Specifically, the multi-quantum well layer 5 is a periodic structure formed by alternating growth of AlGaN and GaN layers, wherein the GaN layer is the well layer and the AlGaN layer is the barrier layer. This is an example, not a limitation. In some preferred embodiments of this example, the thickness of the GaN layer within a single period is 2nm to 4nm, for example, 2nm, 3nm, 4nm, etc., and the thickness of the AlGaN layer within a single period is 8nm to 20nm, for example, 10nm, 12nm, 14nm, etc. The number of alternating growth periods of AlGaN and GaN layers in the multi-quantum well layer 5 is 5 to 12, for example, 8, meaning a total of 8 quantum well layers are grown.

[0033] Example 2

[0034] Please see Figure 2The 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 S209, wherein:

[0035] Step S201: Provide a sapphire substrate required for growth.

[0036] Step S202: Grow a buffer layer with a thickness of 150nm to 300nm.

[0037] In this embodiment, the buffer layer includes a low-temperature Al / AlN / NH3 superlattice layer with a high V / III ratio and a high-temperature Al / AlN / H2 superlattice with a low V / III ratio. It should be noted that the Al / AlN / NH3 superlattice layer and the Al / AlN / H2 superlattice are sequentially deposited on the sapphire substrate. Trimethylaluminum (TMAl), trimethylgallium or triethylgallium (TMGa or TEGa) and ammonia are used as precursors for group III and group V sources, respectively. Silane and magnesium pyrocene are used as precursors for N-type dopant and P-type dopant, respectively. Nitrogen and hydrogen are used as carrier gases.

[0038] Specifically, the growth temperature range for the Al / AlN / NH3 superlattice layer is 800℃~900℃, the growth pressure range is 30 torr~80 torr, the molar ratio of V / III is between 2000 and 4000, the NH3 flow rate is 3000 sccm~6000 sccm, and the Al flow rate is 100 sccm~200 sccm. When growing an Al sublayer in a single cycle, only the Al source is introduced for growth, and the time is 5s~15s without introducing NH3; when growing an AlN sublayer in a single cycle, both the Al source and NH3 are introduced simultaneously for growth, and the growth time is 1min~3min; when growing an NH3 sublayer in a single cycle, only NH3 is introduced for annealing, and the Al source is not introduced for growth, and the time is 5s~10s.

[0039] In addition, the growth temperature range of the Al / AlN / H2 superlattice layer is 1050℃~1200℃, the growth pressure range is 30torr~80torr, the molar ratio of V / III is between 50 and 500, the NH3 flow rate is 100sccm~500sccm, and the Al flow rate is 500sccm~1000sccm. When growing the Al sublayer in a single cycle, only the Al source is introduced for growth, and the time is 5s~15s without introducing NH3; when growing the AlN sublayer in a single cycle, both the Al source and NH3 are introduced simultaneously for growth, and the growth time is 1min~3min; when growing the H2 sublayer in a single cycle, only H2 is introduced for annealing, and the Al source is not introduced for growth, and the time is 5s~10s.

[0040] Understandably, the Al sublayer in the superlattice is set up to first wet the substrate or the already grown epitaxial layer with the Al layer, which is beneficial to improve the migration ability of the subsequent AlN sublayer, thereby obtaining an epitaxial layer with better crystal quality.

[0041] Step S203: Grow an undoped AlGaN layer with a thickness of 1 μm to 3 μm.

[0042] It should be noted that the growth temperature of the undoped AlGaN layer is 1050℃~1200℃, the growth pressure is 50 torr~100 torr, and the Al composition is 0.3~0.8.

[0043] Step S204: Grow an N-type doped AlGaN layer with a thickness of 1 μm to 3 μm.

[0044] Specifically, the N-type doped AlGaN layer is doped with Si, with a growth temperature of 1100℃~1200℃, a growth pressure of 50 torr~100 torr, and a Si doping concentration of 10¹⁹ cm⁻¹. 3 ~1020cm 3 The Al component is 0.2–0.6%.

[0045] Step S205: Alternately grow quantum well layers and quantum barrier layers to obtain a multi-quantum well layer with a growth thickness of 50 nm to 288 nm.

[0046] It should be noted that the multi-quantum well layer consists of 5 to 12 cycles of GaN / AlGaN, where GaN is the well layer and AlGaN is the barrier layer. The well layer is grown at a temperature of 900℃ to 1000℃ and a growth pressure of 50 torr to 200 torr; the barrier layer is grown at a temperature of 1000℃ to 1100℃ and a pressure of 50 torr to 100 torr, with an Al composition of 0.1 to 0.5%.

[0047] Step S206: Grow an electron blocking layer with a thickness of 20 nm to 100 nm.

[0048] The electron blocking layer is grown at a temperature of 1000℃ to 1100℃, a growth pressure of 50 torr to 100 torr, and an Al composition of 0.1 to 0.5.

[0049] Step S207: Grow a P-type doped GaN layer with a thickness of 30 nm to 200 nm.

[0050] The p-type doped AlGaN layer contains Mg dopant, with a growth temperature of 950℃~1050℃, a growth pressure of 50 torr~300 torr, and a Mg doping concentration of 10¹⁹ cm⁻¹. 3 ~1020cm3 .

[0051] Step S208: Grow an AlGaN contact layer with a thickness of 10 nm to 50 nm.

[0052] Specifically, the growth temperature of the AlGaN contact layer is 1000℃~1100℃, the growth pressure is 50 torr~100 torr, and the Al composition is 0.0~0.3.

[0053] Step S209, annealing.

[0054] In this embodiment, after the epitaxial structure growth is completed, the temperature of the reaction chamber is lowered and annealed in a nitrogen atmosphere at a temperature of 650°C to 850°C for 5 to 15 minutes. When the temperature reaches approximately room temperature, the epitaxial growth is completed.

[0055] In summary, the LED epitaxial wafer and its epitaxial growth method in the embodiments of the present invention utilize a buffer layer composed of a low-temperature Al / AlN / NH3 superlattice layer with a high V / III ratio and a high-temperature Al / AlN / H2 superlattice layer with a low V / III ratio. The low-temperature Al / AlN / NH3 superlattice layer with a high V / III ratio in the buffer layer grows in a three-dimensional mode, which can effectively annihilate dislocations caused by lattice mismatch between the substrate and the epitaxial layer, preventing defects from continuing to extend into the epitaxial layer. Then, through NH3 annealing, the epitaxial layer is made more inclined to grow in a three-dimensional mode, further reducing dislocations. The high-temperature Al / AlN / H2 superlattice layer with a low V / III ratio in the buffer layer grows in a two-dimensional mode. By covering the above-mentioned grown three-dimensional Al / AlN superlattice layer, a relatively flat epitaxial layer can be obtained. Then, through H2 annealing, the surface of the epitaxial layer becomes smoother, and the crystal quality is further improved.

[0056] Example 3

[0057] 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.

[0058] 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, It includes a buffer layer, which is composed of an Al / AlN / NH3 superlattice layer and an Al / AlN / H2 superlattice layer, and the Al / AlN / H2 superlattice layer is deposited on the Al / AlN / NH3 superlattice layer; The Al / AlN / NH3 superlattice layer is a periodic structure formed by the alternating growth of Al sublayers, AlN sublayers, and NH3 sublayers, and the Al / AlN / H2 superlattice layer is a periodic structure formed by the alternating growth of Al sublayers, AlN sublayers, and H2 sublayers. The Al / AlN / NH3 superlattice layer is grown in a three-dimensional mode, while the Al / AlN / H2 superlattice layer is grown in a two-dimensional mode. The molar ratio of V / III in the Al / AlN / NH3 superlattice layer ranges from 2000 to 4000, and the molar ratio of V / III in the Al / AlN / H2 superlattice layer ranges from 50 to 500.

2. The LED epitaxial wafer according to claim 1, characterized in that, The LED epitaxial wafer also includes a sapphire substrate, an undoped AlGaN layer, an N-type doped AlGaN layer, a multiple quantum well layer, an electron blocking layer, a P-type doped GaN layer, and an AlGaN contact layer. The buffer layer, the undoped AlGaN layer, the N-type doped AlGaN layer, the multiple quantum well layer, the electron blocking layer, the P-type doped GaN layer, and the AlGaN contact layer are sequentially epitaxially grown on the sapphire substrate.

3. The LED epitaxial wafer according to claim 2, characterized in that, The total thickness of the Al / AlN / NH3 superlattice layer is 50nm~100nm, the thickness of the Al sublayer in a single period is 1nm~2nm, the thickness of the AlN sublayer in a single period is 5nm~10nm, the total thickness of the Al / AlN / H2 superlattice layer is 100nm~200nm, the thickness of the Al sublayer in a single period is 1nm~2nm, the thickness of the AlN sublayer in a single period is 10nm~20nm, the thickness of the undoped AlGaN layer is 1μm~3μm, the thickness of the N-type doped AlGaN layer is 1μm~3μm, the thickness of the multiple quantum well layer is 50nm~288nm, the thickness of the electron blocking layer is 20nm~100nm, the thickness of the P-type doped GaN layer is 30nm~200nm, and the thickness of the AlGaN contact layer is 10nm~50nm.

4. The LED epitaxial wafer according to claim 2, characterized in that, The multiple quantum well layer is a periodic structure formed by alternating growth of AlGaN layers and GaN layers. The GaN layer is a well layer with a thickness of 2nm to 4nm in a single period, and the AlGaN layer is a barrier layer with a thickness of 8nm to 20nm in a single period.

5. A method for epitaxial growth of LED epitaxial wafers, characterized in that, The epitaxial growth method for preparing the LED epitaxial wafer according to any one of claims 1-4 includes: During the growth of the buffer layer, the Al sublayer, AlN sublayer, and NH3 sublayer are controlled to grow alternately in a cycle to form an Al / AlN / NH3 superlattice layer. The Al sublayer, the AlN sublayer, and the H2 sublayer are controlled to grow alternately on the Al / AlN / NH3 superlattice layer to form an Al / AlN / H2 superlattice layer; The Al / AlN / NH3 superlattice layer is grown in a three-dimensional mode, while the Al / AlN / H2 superlattice layer is grown in a two-dimensional mode. The molar ratio of V / III in the Al / AlN / NH3 superlattice layer ranges from 2000 to 4000, and the molar ratio of V / III in the Al / AlN / H2 superlattice layer ranges from 50 to 500.

6. The epitaxial growth method for LED epitaxial wafers according to claim 5, characterized in that, The epitaxial growth method further includes: Provide a sapphire substrate required for growth; The buffer layer, undoped AlGaN layer, N-type doped AlGaN layer, multiple quantum well layer, electron blocking layer, P-type doped GaN layer and AlGaN contact layer are epitaxially grown sequentially on the sapphire substrate.

7. The epitaxial growth method for LED epitaxial wafers according to claim 5, characterized in that, The growth temperature of the Al / AlN / NH3 superlattice layer is 800℃~900℃, the growth pressure is 30 torr~80 torr, the molar ratio of V / III is between 2000 and 4000, and the NH3 layer is annealed by only introducing NH3 in a single cycle for 5s~10s, without introducing a MO source for growth.

8. The epitaxial growth method for LED epitaxial wafers according to claim 5, characterized in that, The growth temperature of the Al / AlN / H2 superlattice layer is 1050℃~1200℃, the growth pressure is 30 torr~80 torr, the molar ratio of V / III is between 50 and 500, and the H2 layer is annealed by only introducing H2 in a single cycle for 5s~10s, without introducing a MO source for growth.

9. The epitaxial growth method for LED epitaxial wafers according to claim 6, characterized in that, The growth temperature of the undoped AlGaN layer is 1050℃-1200℃, the growth pressure is between 50 torr and 100 torr, and the Al composition is between 0.3 and 0.

8.

10. An LED chip, characterized in that, Includes the LED epitaxial wafer as described in any one of claims 1-4.

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