CN109860345B

CN109860345B - LED epitaxial structure growth method

Info

Publication number: CN109860345B
Application number: CN201910047686.2A
Authority: CN
Inventors: 徐平; 季辉; 何鹏
Original assignee: Xiangneng Hualei Optoelectrical Co Ltd
Current assignee: Xiangneng Hualei Optoelectrical Co Ltd
Priority date: 2019-01-18
Filing date: 2019-01-18
Publication date: 2020-01-10
Anticipated expiration: 2039-01-18
Also published as: CN109860345A

Abstract

The invention discloses a method for growing an LED epitaxial structure, which comprises the following steps: processing the sapphire substrate; growing a low-temperature GaN buffer layer on the sapphire substrate, and processing the low-temperature GaN buffer layer to form irregular islands on the low-temperature GaN buffer layer; growing an undoped GaN layer on the low-temperature GaN buffer layer; growing an N-type GaN layer doped with Si on the undoped GaN layer; growing a multi-quantum well layer on the Si-doped N-type GaN layer, and growing an AlGaN electronic barrier layer on the multi-quantum well layer; growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer; and cooling. By the growth method, the luminous efficiency of the LED can be effectively improved, the warping of the epitaxial wafer can be reduced, the yield of the GaN epitaxial wafer is improved, the surface of the epitaxial layer is smooth, and the appearance is better.

Description

LED epitaxial structure growth method

Technical Field

The invention relates to the technical field of LEDs, in particular to a growing method of an LED epitaxial structure.

Background

A Light-Emitting Diode (LED) is a semiconductor electronic device that converts electrical energy into optical energy. When current flows, electrons and holes recombine in the quantum well to emit monochromatic light. As a novel efficient, environment-friendly and green solid-state lighting source, the LED has the advantages of low voltage, low power consumption, small size, light weight, long service life, high reliability, rich colors and the like. At present, the scale of domestic LED production is gradually enlarged, but the LED still has the problem of low luminous efficiency, and the energy-saving effect of the LED is influenced.

In the traditional LED epitaxial InGaN/GaN multi-quantum well layer growing method, the InGaN/GaN multi-quantum well layer is low in quality, the radiation efficiency of a light emitting region of a quantum well is low, the improvement of the LED light emitting efficiency is seriously hindered, and the energy-saving effect of an LED is influenced.

Therefore, it is an urgent technical problem to be solved in the art to provide a method for growing an LED epitaxial structure, so as to solve the problem of low recombination efficiency of light emission radiation in the conventional LED multiple quantum well layer, thereby improving the light emission efficiency of the LED.

Disclosure of Invention

In view of this, the invention provides a method for growing an LED epitaxial structure, which solves the problem of low quantum well luminescence radiation recombination efficiency in the existing LED epitaxial growth method, thereby improving the LED luminescence efficiency, reducing the warpage of an epitaxial wafer, and improving the yield of products.

The invention provides a method for growing an LED epitaxial structure, which comprises the following steps:

processing the sapphire substrate;

growing a low-temperature GaN buffer layer on the sapphire substrate, and processing the low-temperature GaN buffer layer to form irregular islands on the low-temperature GaN buffer layer;

growing an undoped GaN layer on the low-temperature GaN buffer layer;

growing an N-type GaN layer doped with Si on the undoped GaN layer;

growing a multiple quantum well layer on the Si-doped N-type GaN layer, the multiple quantum well layer including high temperature In_x2Ga_(1-x2)N well layer, high temperature GaN barrier layer, low temperature In_x3Ga_(1-x3)The N-well layer and the low-temperature GaN barrier layer are grown by the following steps:

controlling the pressure of the reaction chamber between 200 and 280mbar and the temperature of the reaction chamber between 500 and 580 ℃, and introducing 20000 and 30000sccm NH₃200-300sccm TEGa, 60-90sccm SiH₄And 1300 plus 1400sccm TMIn with a growth thickness D₁In of Si doped_x1Ga_(1-x1)N transition layer, D₁60-80nm, wherein the Si doping concentration is reduced by 1E +17atoms/cm per second³At a speed of from 4E +19atoms/cm³Linear ramp down to 2E +19atoms/cm³；

Keeping the pressure of the reaction cavity and NH₃The flow rate of the TEGa is unchanged, the temperature of the reaction chamber is raised to 1000-1100 ℃, the flow rate of the stable TMIn is 1300-1400sccm, and the growth thickness is D₂High temperature In of_x2Ga_(1-x2)An N well layer with an In doping concentration of 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³，D₂72-104nm, wherein D₂＝(1.2-1.3)D₁，x₁And x₂Are all in the range of 0.26-0.32, and x₂＝x₁+0.01；

Keeping the pressure and the temperature of the reaction cavity unchanged,TMGa of 150-₂And 6000 plus 8000sccm NH₃The mol ratio of nitrogen atoms to gallium atoms is controlled to be 800:1-900:1, the temperature in the reaction cavity is controlled to be gradually reduced from 1100 ℃ to 1020 ℃ at the speed of reducing 0.4-0.5 ℃ per second in the growth process, and the growth thickness is D₃High temperature GaN barrier layer of (D)₃＝4-6nm；

Periodically growing the high temperature In_x2Ga_(1-x2)The N well layer and the high-temperature GaN barrier layer have the growth cycle number of 2-4;

reducing the temperature of the reaction chamber to 550-₃200-300sccm TEGa, 60-90sccm SiH₄And 1300 plus 1400sccm TMIn with a growth thickness D₄Low temperature In of_x3Ga_(1-x3)An N well layer with an In doping concentration of 4E +20-5E +20atoms/cm³，D₄＝D₂- (10-20) nm, and x₃＝x₂-0.02；

Keeping the pressure and temperature of the reaction chamber unchanged, introducing 150-200sccm TMGa and 200-250L/min N₂And 6000 plus 8000sccm NH₃The molar ratio of nitrogen atoms to gallium atoms is controlled to be 800:1-900:1, and the growth thickness D₅Low temperature GaN barrier layer of (D)₅＝(1.1-1.3)D₃；

Periodically growing the low temperature In_x3Ga_(1-x3)The N well layer and the low-temperature GaN barrier layer have the growth cycle number of 3-5;

growing an AlGaN electronic barrier layer on the multi-quantum well layer;

growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer;

and cooling.

Preferably, the sapphire substrate is treated by further introducing 100-130L/min H at the temperature of 620-650 ℃ and the pressure of the reaction chamber of 100-300mbar₂The sapphire substrate was processed for 5 to 10 minutes under the conditions of (1).

Preferably, the low-temperature GaN buffer layer is grown on the sapphire substrate and is processed to form irregular islands on the low-temperature GaN buffer layer, and further,

introducing 10000-20000sccm NH into the reaction chamber at the temperature of 500-600 ℃ and the pressure of 300-600mbar₃TMGa 50-100sccm, H100-130L/min₂Growing the low-temperature GaN buffer layer on the sapphire substrate under the condition (1), wherein the thickness of the low-temperature GaN buffer layer is 20-40 nm;

introducing NH of 30000-40000sccm at the temperature of 1000-1100 ℃ and the pressure of the reaction chamber of 300-600mbar₃100-130L/min H₂Under the condition (2), the irregular islands are formed on the low-temperature GaN buffer layer.

Preferably, the non-doped GaN layer is grown on the low-temperature GaN buffer layer, and further, NH of 30000-₃200-400sccm TMGa, 100-130L/min H₂Growing the non-doped GaN layer on the low-temperature GaN buffer layer under the condition (2-4 microns).

Preferably, the Si-doped N-type GaN layer is grown on the non-doped GaN layer by keeping the pressure of the reaction chamber at 300-₃200-400sccm TMGa, 100-130L/min H₂And 20-50sccm SiH₄Continuously growing Si-doped N-type GaN with the thickness of 3-4 μm on the undoped GaN layer, wherein the doping concentration of Si is 5E18-1E19atoms/cm³。

Preferably, the AlGaN electron blocking layer is grown on the multi-quantum well layer, and further, NH of 50000-₃TMGa 30-60sccm, H100-130L/min₂100-TMAl of 130sccm, and 1000-Cp of 1300sccm₂Growing the AlGaN electron barrier layer on the multi-quantum well layer under the condition of Mg, wherein the thickness of the AlGaN layer is 40-60nm, and the concentration of Mg doping is 1E19-1E20atoms/cm³。

Preferably, the AlGaN electron blocking layerGrowing a P-type GaN layer doped with Mg, and introducing NH of 50000-70000sccm at a reaction chamber temperature of 950-1000 ℃ and a reaction chamber pressure of 400-900mbar₃20-100sccm of TMGa, 100-₂1000-Cp of 3000sccm₂Growing a P-type GaN layer doped with Mg with a thickness of 50-200nm under the condition of Mg, wherein the Mg doping concentration is 1E19-1E20atoms/cm³。

Preferably, the temperature is reduced and cooled, and further, the temperature is maintained for 20-30min under the condition that the temperature is 650-.

Compared with the prior art, the LED epitaxial structure growth method provided by the invention at least realizes the following beneficial effects:

the LED epitaxial structure growth method of the invention firstly grows In doped with Si when growing multiple quantum wells_x1Ga_(1-x1)The N transition layer can prevent defects generated by lattice mismatch in the early stage from extending upwards, so that the dislocation density is reduced, the crystal quality is improved, and the performances of LED brightness, electric leakage, static resistance and the like are improved.

The LED epitaxial structure growth method can effectively improve the concentration of holes and the recombination probability of electrons and the holes, and the growth mode is favorable for improving the doping efficiency of In and forming indium-rich regions In quantum wells, so that current carriers are easily captured by the indium-rich regions to generate radiative recombination, thereby improving the luminous efficiency. The whole quantum well layer forms a gradient capacitor structure by adopting a high-temperature periodic growth mode and a low-temperature periodic growth mode, so that the current-limiting effect can be better achieved, and the light-emitting attenuation effect under high current density is greatly reduced.

According to the invention, the doping concentration of Si and In and the temperature are controlled to change regularly In the process of growing the multi-quantum well layer, and the lattice matching degree between the epitaxial layers In the multi-quantum well can be improved, so that the stress existing In the process of growing the multi-quantum well layer can be reduced, and when the AlGaN electronic barrier layer is continuously grown on the basis, the whole epitaxial material reaches a completely relaxed state, so that the stress caused by lattice mismatch In the process of growing the LED epitaxial material is eliminated, the stress control window of the epitaxial film material is obviously enlarged, the warping of an epitaxial wafer can be reduced, and the qualification rate of the GaN epitaxial wafer is improved.

In the growth process of the quantum well, the control of the two-dimensional growth process of the nitrogen atoms and the gallium atoms is realized by controlling the molar ratio of the nitrogen atoms to the gallium atoms, so that the surface of the epitaxial layer becomes flat;

by the growth method, the luminous efficiency of the LED can be effectively improved, the warping of the epitaxial wafer can be reduced, the yield of the GaN epitaxial wafer is improved, the surface of the epitaxial layer is smooth, and the appearance is better.

Of course, it is not necessary for any product in which the present invention is practiced to achieve all of the above-described technical effects simultaneously.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a flowchart of a method for growing an epitaxial structure of an LED according to embodiment 1 of the present invention.

Detailed Description

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In this embodiment, the LED epitaxial structure growth method provided by the present invention is adopted, a high-brightness GaN-based LED epitaxial wafer is grown by MOCVD of a model of VECOO K465i, and high-purity H is adopted₂Or high purity N₂Or high purity H₂And high purity N₂The mixed gas of (2) is used as a carrier gas, high-purity NH₃As the N source, a metal organic source, trimethyl gallium (TMGa) as the gallium source, trimethyl indium (TMIn) as the indium source, and an N-type dopant, Silane (SiH)₄) Trimethylaluminum (TMAl) as the aluminum source and magnesium diclomelate (CP) as the P-type dopant₂Mg), the reaction pressure is between 70mbar and 900 mbar.

Example 1:

with reference to fig. 1, this embodiment provides a method for growing an LED epitaxial structure, which includes the following steps:

step 101, processing a sapphire substrate:

introducing 100L/min H at 620 deg.C and reaction chamber pressure of 100mbar₂The sapphire substrate was processed for 5 minutes.

102, growing a low-temperature GaN buffer layer on the sapphire substrate, and processing the low-temperature GaN buffer layer to form irregular islands on the low-temperature GaN buffer layer, wherein the specific steps are as follows:

1): introducing 10000sccm of NH into the reaction chamber at the temperature of 500 ℃ and the pressure of the reaction chamber of 300mbar₃TMGa of 50sccm, H of 100L/min₂Growing the low-temperature GaN buffer layer on the sapphire substrate under the condition (1), wherein the thickness of the low-temperature GaN buffer layer is 20 nm;

2) introducing 30000sccm of NH into the reaction chamber at 1000 deg.C and 300mbar₃100L/min H₂Under the conditions of (1) at said low temperature GaAnd the irregular islands are formed on the N buffer layer.

Step 103, growing an undoped GaN layer on the low-temperature GaN buffer layer:

introducing 30000sccm of NH into the reaction chamber at the temperature of 1000 ℃ and the pressure of the reaction chamber of 300mbar₃TMGa of 200sccm, H of 100L/min₂Under the condition (2), growing the non-doped GaN layer on the low-temperature GaN buffer layer, wherein the thickness of the non-doped GaN layer is 2 microns.

Step 104, growing an N-type GaN layer doped with Si on the undoped GaN layer:

keeping the pressure of the reaction cavity at 300mbar and the temperature of the reaction cavity at 1000 ℃, and introducing NH with the flow rate of 30000sccm₃TMGa of 200sccm, H of 100L/min₂And 20sccm of SiH₄Continuously growing Si-doped N-type GaN of 3 μm on the undoped GaN layer, wherein the doping concentration of Si is 5E18atoms/cm³。

Step 105 of growing a multiple quantum well layer on the Si-doped N-type GaN layer, the multiple quantum well layer including high temperature In_x2Ga_(1-x2)N well layer, high temperature GaN barrier layer, low temperature In_x3Ga_(1-x3)The N-well layer and the low-temperature GaN barrier layer are grown by the following steps:

a) controlling the pressure of the reaction cavity between 200mbar and the temperature of the reaction cavity between 500 ℃, and introducing NH of 20000sccm₃TEGa of 200sccm, SiH of 60sccm₄And 1300sccm TMIn grown to a thickness D₁In of Si doped_x1Ga_(1-x1)N transition layer, D₁60nm, with the Si doping concentration decreasing by 1E +17atoms/cm per second³At a speed of from 4E +19atoms/cm³Linear ramp down to 2E +19atoms/cm³；

In doped with Si is grown first when growing multiple quantum wells_x1Ga_(1-x1)The N transition layer can prevent defects generated by lattice mismatch in the early stage from extending upwards, so that the dislocation density is reduced, the crystal quality is improved, and the performances of the LED such as brightness, electric leakage, static resistance and the like are improved;

b) keeping the pressure of the reaction cavity and NH₃And the flow rate of TEGa is not changed, the reaction chamber is raisedThe temperature is up to 1000 ℃, the flow of the stable TMIn is 1300sccm, and the growth thickness is D₂High temperature In of_x2Ga_(1-x2)An N well layer with an In doping concentration of 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³，D₂72nm, wherein D₂＝1.2D₁，x₁And x₂Are all in the range of 0.26-0.32, and x₂＝x₁+0.01；

c) Keeping the pressure and temperature of the reaction chamber constant, introducing 150-200sccm TMGa and 200L/min N₂And NH of 6000sccm₃The mol ratio of nitrogen atoms to gallium atoms is controlled to be 800:1, the temperature in the reaction cavity is controlled to be gradually reduced from 1100 ℃ to 1020 ℃ at the speed of reducing 0.4-0.5 ℃ per second in the growth process, and the growth thickness is D₃High temperature GaN barrier layer of (D)₃＝4nm；

Repeating the above steps b) and c), periodically growing the high temperature In_x2Ga_(1-x2)The N well layer and the high-temperature GaN barrier layer have the growth cycle number of 2;

controlling the doping concentrations of Si and In and the temperature to change regularly during the growth of the multiple quantum well layer can improve the lattice matching degree between the epitaxial layers inside the multiple quantum well, and thus can reduce the stress existing when the multiple quantum well layer is grown. When the AlGaN electronic barrier layer continues to grow on the basis, the whole epitaxial material reaches a completely relaxed state, so that the stress caused by lattice mismatch in the growth process of the LED epitaxial material is eliminated, the stress control window of the epitaxial film material is obviously enlarged, the warping of an epitaxial wafer can be reduced, and the yield of the GaN epitaxial wafer is improved.

d) Reducing the temperature of the reaction chamber to 550 ℃, keeping the pressure of the reaction chamber unchanged, and introducing NH of 20000sccm₃TEGa of 200sccm, SiH of 60sccm₄And 1300sccm TMIn grown to a thickness D₄Low temperature In of_x3Ga_(1-x3)An N well layer with an In doping concentration of 4E +20atoms/cm³，D₄＝D₂-10nm, and x₃＝x₂-0.02；

e) Keeping the pressure and temperature of the reaction chamber constant, introducing 150sccmTMGa, N200L/min₂And NH of 6000sccm₃The molar ratio of nitrogen atoms to gallium atoms is controlled to be 800:1, and the growth thickness D₅Low temperature GaN barrier layer of (D)₅＝1.1D₃；

Repeating the above steps d) and e), periodically growing the low temperature In_x3Ga_(1-x3)The N well layer and the low-temperature GaN barrier layer have the growth cycle number of 3;

the growth process of the quantum well can effectively improve the concentration of the holes and the recombination probability of electrons and the holes, and the growth mode is favorable for improving the doping efficiency of In and forming indium-rich areas In the quantum well, so that current carriers are easily captured by the indium-rich areas to generate radiative recombination, thereby improving the luminous efficiency.

the invention adopts the mode of high-temperature periodic growth firstly and then the mode of low-temperature periodic growth to ensure that the whole quantum well layer forms a gradient capacitor structure, thereby better achieving the current-limiting effect and greatly reducing the luminous attenuation effect under the high current density.

Step 106, growing an AlGaN electron barrier layer on the multi-quantum well layer:

introducing NH of 50000sccm into the reaction chamber at 900 deg.C and 200mbar₃TMGa of 30sccm, H of 100L/min₂TMAl of 100sccm, and Cp of 1000sccm₂Growing the AlGaN electron barrier layer on the multi-quantum well layer under the condition of Mg, wherein the thickness of the AlGaN layer is 40nm, and the concentration of Mg doping is 1E19atoms/cm³。

Step 107, growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer:

introducing 50000sccm NH into the reaction chamber at 950 ℃ and 400mbar₃TMGa of 20sccm, H of 100L/min₂Cp of 1000sccm₂Growing the film with the thickness of 50nm under the condition of MgThe Mg-doped P-type GaN layer of (1E 19 atoms/cm) Mg doping concentration³。

And step 108, cooling:

keeping the temperature at 650 ℃ for 20min, then closing the heating system, closing the gas supply system, and cooling along with the furnace.

Example 2:

the embodiment further provides a method for growing an LED epitaxial structure, which includes the following steps:

step 201, processing a sapphire substrate:

introducing 130L/min H at 650 deg.C and 300mbar in the reaction chamber₂The sapphire substrate was processed for 10 minutes under the conditions of (1).

Step 202, growing a low-temperature GaN buffer layer on the sapphire substrate, and processing the low-temperature GaN buffer layer to form irregular islands on the low-temperature GaN buffer layer, which comprises the following specific steps:

1): introducing NH of 20000sccm at the temperature of 600 ℃ and the pressure of the reaction cavity of 600mbar₃TMGa of 100sccm, H of 130L/min₂Growing the low-temperature GaN buffer layer on the sapphire substrate under the condition (1), wherein the thickness of the low-temperature GaN buffer layer is 40 nm;

2) introducing NH of 40000sccm at 1100 deg.C and 600mbar in the reaction chamber₃130L/min H₂Under the condition (2), the irregular islands are formed on the low-temperature GaN buffer layer.

Step 203, growing an undoped GaN layer on the low-temperature GaN buffer layer:

introducing NH of 40000sccm at the temperature of 1200 ℃ and the pressure of the reaction cavity of 600mbar₃TMGa of 400sccm, H of 130L/min₂Under the condition (2), growing the non-doped GaN layer on the low-temperature GaN buffer layer, wherein the thickness of the non-doped GaN layer is 4 mu m.

Step 204, growing an N-type GaN layer doped with Si on the undoped GaN layer:

keeping the pressure of the reaction cavity at 600mbar and the temperature of the reaction cavity at 1200 ℃, and introducing NH with the flow rate of 60000sccm₃TMGa of 400sccm, H of 130L/min₂And 50sccm of SiH₄Continuously growing Si-doped N-type GaN of 4 μm on the undoped GaN layer, wherein the doping concentration of Si is 1E19atoms/cm³。

Step 205, growing a multi-quantum well layer on the Si-doped N-type GaN layer, wherein the multi-quantum well layer comprises high-temperature In_x2Ga_(1-x2)N well layer, high temperature GaN barrier layer, low temperature In_x3Ga_(1-x3)The N-well layer and the low-temperature GaN barrier layer are grown by the following steps:

a) controlling the pressure of the reaction cavity between 280mbar and the temperature of the reaction cavity between 580 ℃, and introducing 30000sccm NH₃300sccm TEGa, 90sccm SiH₄And 1400sccm TMIn with a growth thickness D₁In of Si doped_x1Ga_(1-x1)N transition layer, D₁80nm, with the Si doping concentration decreasing by 1E +17atoms/cm per second³At a speed of from 4E +19atoms/cm³Linear ramp down to 2E +19atoms/cm³；

b) Keeping the pressure of the reaction cavity and NH₃The flow rate of the TEGa is not changed, the temperature of the reaction chamber is increased to 1100 ℃, the flow rate of the stable TMIn is 1400sccm, and the growth thickness is D₂High temperature In of_x2Ga_(1-x2)An N well layer with an In doping concentration of 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³，D₂104nm, wherein D₂＝1.3D₁，x₁And x₂Are all in the range of 0.26-0.32, and x₂＝x₁+0.01；

c) Keeping the pressure and temperature of the reaction chamber constant, introducing 200sccm of TMGa and 250L/min of N₂And NH of 8000sccm₃The mol ratio of nitrogen atoms to gallium atoms is controlled to be 900:1, the temperature in the reaction cavity is controlled to be gradually reduced from 1100 ℃ to 1020 ℃ at the speed of reducing 0.4-0.5 ℃ per second in the growth process, and the growth thickness is D₃High temperature GaN barrier layer of (D)₃＝6nm；

Repeating the above steps b) and c), periodically growing the high temperature In_x2Ga_(1-x2)The N well layer and the high-temperature GaN barrier layer have the growth cycle number of 4;

d) reducing the temperature of the reaction cavity to 600 ℃, keeping the pressure of the reaction cavity unchanged, and introducing NH of 30000sccm₃300sccm TEGa, 90sccm SiH₄And 1400sccm TMIn grown to a thickness D₄Low temperature In of_x3Ga_(1-x3)An N well layer with an In doping concentration of 5E +20atoms/cm³，D₄＝D₂-20nm, and x₃＝x₂-0.02；

e) Keeping the pressure and temperature of the reaction chamber constant, introducing 200sccm of TMGa and 250L/min of N₂And NH of 8000sccm₃The molar ratio of nitrogen atoms to gallium atoms is controlled to be 900:1, and the growth thickness D₅Low temperature GaN barrier layer of (D)₅＝1.3D₃；

Repeating the above steps d) and e), periodically growing the low temperature In_x3Ga_(1-x3)The N well layer and the low-temperature GaN barrier layer have the growth cycle number of 5;

step 206, growing an AlGaN electron blocking layer on the multi-quantum well layer:

introducing 70000sccm NH into the reaction chamber at 950 deg.C and 400mbar pressure₃TMGa of 60sccm, H of 130L/min₂TMAl of 130sccm, and Cp of 1300sccm₂Growing the AlGaN electron barrier layer on the multi-quantum well layer under the condition of Mg, wherein the thickness of the AlGaN layer is 60nm, and the concentration of Mg doping is 1E20atoms/cm³。

Step 207, growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer:

introducing 70000sccm NH into the reaction chamber at the temperature of 1000 ℃ and the pressure of 900mbar₃TMGa of 100sccm, H of 130L/min₂3000sccm Cp₂Growing a P-type GaN layer doped with Mg with the thickness of 200nm under the condition of Mg, wherein the Mg doping concentration is 1E20atoms/cm³。

And step 208, cooling:

keeping the temperature at 680 ℃ for 30min, then closing the heating system, closing the gas supply system, and cooling along with the furnace.

Example 3:

step 301, processing a sapphire substrate:

introducing 120L/min H at 635 ℃ and a reaction chamber pressure of 200mbar₂The sapphire substrate was processed for 7 minutes.

Step 302, growing a low-temperature GaN buffer layer on the sapphire substrate, and processing the low-temperature GaN buffer layer to form irregular islands on the low-temperature GaN buffer layer, which comprises the following steps:

1): introducing NH of 15000sccm at 550 deg.C and reaction chamber pressure of 450mbar₃TMGa of 75sccm, H of 115L/min₂Growing the low-temperature GaN buffer layer on the sapphire substrate under the condition (1), wherein the thickness of the low-temperature GaN buffer layer is 30 nm;

2) introducing 35000sccm NH into the reaction chamber at 1050 deg.C and 450mbar pressure₃115L/min H₂Under the condition (2), the irregular islands are formed on the low-temperature GaN buffer layer.

Step 303, growing an undoped GaN layer on the low-temperature GaN buffer layer:

introducing 35000sccm NH into the reaction chamber at 1100 deg.C and 450mbar pressure₃TMGa of 300sccm, H of 115L/min₂Under the condition (3), growing the non-doped GaN layer on the low-temperature GaN buffer layer, wherein the thickness of the non-doped GaN layer is 3 μm.

Step 304, growing a Si-doped N-type GaN layer on the undoped GaN layer:

keeping the pressure of the reaction cavity at 450mbar and the temperature of the reaction cavity at 1100 ℃, and introducing NH with the flow rate of 45000sccm₃TMGa of 300sccm, H of 115L/min₂And 35sccm of SiH₄In the non-doped GaN layerContinuously growing Si-doped N-type GaN of 3-4 μm, wherein the doping concentration of Si is 7.5E18atoms/cm³。

Step 305 of growing a multiple quantum well layer on the Si-doped N-type GaN layer, the multiple quantum well layer including high temperature In_x2Ga_(1-x2)N well layer, high temperature GaN barrier layer, low temperature In_x3Ga_(1-x3)The N-well layer and the low-temperature GaN barrier layer are grown by the following steps:

a) controlling the pressure of the reaction chamber between 240mbar and the temperature of the reaction chamber between 540 ℃, and introducing NH of 25000sccm₃250sccm TEGa, 75sccm SiH₄And 1350sccm TMIn grown to a thickness D₁In of Si doped_x1Ga_(1-x1)N transition layer, D₁70nm, with the Si doping concentration decreasing by 1E +17atoms/cm per second³At a speed of from 4E +19atoms/cm³Linear ramp down to 2E +19atoms/cm³；

b) Keeping the pressure of the reaction cavity and NH₃The flow rate of TEGa is not changed, the temperature of the reaction chamber is increased to 1050 ℃, the flow rate of stable TMIn is 1350sccm, and the growth thickness is D₂High temperature In of_x2Ga_(1-x2)An N well layer with an In doping concentration of 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³，D₂88nm, wherein D₂＝1.25D₁，x₁And x₂Are all in the range of 0.26-0.32, and x₂＝x₁+0.01；

c) Keeping the pressure and temperature of the reaction chamber constant, introducing TMGa of 175sccm and N of 225L/min₂And NH of 7000sccm₃The mol ratio of nitrogen atoms to gallium atoms is controlled to be 850:1, the temperature in the reaction cavity is controlled to be gradually reduced from 1100 ℃ to 1020 ℃ at the speed of reducing 0.4-0.5 ℃ per second in the growth process, and the growth thickness is D₃High temperature GaN barrier layer of (D)₃＝5nm；

Repeating the above steps b) and c), periodically growing the high temperature In_x2Ga_(1-x2)The N well layer and the high-temperature GaN barrier layer have the growth cycle number of 3;

d) the temperature of the reaction cavity is reduced to 575 ℃, and the pressure of the reaction cavity is kept constantAlternatively, NH of 25000sccm was introduced₃250sccm TEGa, 75sccm SiH₄And 1350sccm TMIn grown to a thickness D₄Low temperature In of_x3Ga_(1-x3)An N well layer with an In doping concentration of 4.5E +20atoms/cm³，D₄＝D₂-15nm, and x₃＝x₂-0.02；

e) Keeping the pressure and temperature of the reaction chamber constant, introducing TMGa of 175sccm and N of 225L/min₂And NH of 7000sccm₃And the molar ratio of nitrogen atoms to gallium atoms is controlled to be 850:1, and the growth thickness D₅Low temperature GaN barrier layer of (D)₅＝1.2D₃；

Repeating the above steps d) and e), periodically growing the low temperature In_x3Ga_(1-x3)The N well layer and the low-temperature GaN barrier layer have the growth cycle number of 4;

step 306, growing an AlGaN electron barrier layer on the multi-quantum well layer:

introducing NH of 60000sccm at a reaction chamber temperature of 925 ℃ and a reaction chamber pressure of 300mbar₃TMGa of 45sccm, H of 115L/min₂115sccm TMAl, and 1150sccm Cp₂Growing the AlGaN electron barrier layer on the multi-quantum well layer under the condition of Mg, wherein the thickness of the AlGaN layer is 50nm, and the concentration of Mg doping is 5E19atoms/cm³。

Step 307, growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer:

introducing 60000sccm NH into the reaction chamber at 975 deg.C and 650mbar pressure₃TMGa of 60sccm, H of 115L/min₂Cp of 2000sccm₂Growing a P-type GaN layer doped with Mg with the thickness of 125nm under the condition of Mg, wherein the Mg doping concentration is 5E19atoms/cm³。

And 108, cooling:

keeping the temperature at 665 deg.C for 25min, closing heating system and gas supply system, and cooling with furnace.

Example 4:

step 401, processing the sapphire substrate:

introducing 120L/min H at 630 deg.C and reaction chamber pressure of 120mbar₂The sapphire substrate was processed for 6 minutes.

Step 402, growing a low-temperature GaN buffer layer on the sapphire substrate, and processing the low-temperature GaN buffer layer to form irregular islands on the low-temperature GaN buffer layer, which comprises the following specific steps:

1): introducing 11000sccm NH at the temperature of 520 ℃ and the pressure of a reaction cavity of 320mbar₃TMGa of 60sccm, H of 120L/min₂Growing the low-temperature GaN buffer layer on the sapphire substrate under the condition (1), wherein the thickness of the low-temperature GaN buffer layer is 25 nm;

2) introducing 31000sccm NH into the reaction chamber at 1010 deg.C and 320mbar₃120L/min H₂Under the condition (2), the irregular islands are formed on the low-temperature GaN buffer layer.

Step 403, growing an undoped GaN layer on the low-temperature GaN buffer layer:

introducing 31000sccm of NH into the reaction chamber at 1010 deg.C and 320mbar in the reaction chamber₃TMGa of 250sccm, H of 120L/min₂Under the condition (2), growing the non-doped GaN layer on the low-temperature GaN buffer layer, wherein the thickness of the non-doped GaN layer is 2 microns.

Step 404, growing a Si-doped N-type GaN layer on the undoped GaN layer:

keeping the pressure of the reaction cavity at 320mbar and the temperature of the reaction cavity at 1010 ℃, and introducing NH with the flow rate of 40000sccm₃TMGa of 250sccm, H of 120L/min₂And 25sccm of SiH₄Continuously growing Si-doped N-type GaN with the doping concentration of 5.2E18atoms/cm on the undoped GaN layer by 3 mu m³。

Step 405, growing a multiple quantum well layer on the Si-doped N-type GaN layer, the multiple quantum well layer comprising high temperature In_x2Ga_(1-x2)N well layer, high temperature GaN barrier layer, low temperature In_x3Ga_(1-x3)N-well layerAnd a low-temperature GaN barrier layer, wherein the growth step comprises:

a) controlling the pressure of the reaction cavity between 210mbar and the temperature of the reaction cavity between 510 ℃, and introducing 21000sccm of NH₃210sccm TEGa, 65sccm SiH₄And 1310sccm TMIn with a growth thickness D₁In of Si doped_x1Ga_(1-x1)N transition layer, D₁65nm, with the Si doping concentration decreasing by 1E +17atoms/cm per second³At a speed of from 4E +19atoms/cm³Linear ramp down to 2E +19atoms/cm³；

b) Keeping the pressure of the reaction cavity and NH₃The flow rate of the TEGa is unchanged, the temperature of the reaction chamber is increased to 1010 ℃, the flow rate of the stable TMIn is 1310sccm, and the growth thickness is D₂High temperature In of_x2Ga_(1-x2)An N well layer with an In doping concentration of 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³，D₂80nm, wherein D₂＝1.2D₁，x₁And x₂Are all in the range of 0.26-0.32, and x₂＝x₁+0.01；

c) Keeping the pressure and temperature of the reaction chamber constant, introducing 160sccm of TMGa and 210L/min of N₂And NH of 6100sccm₃The mol ratio of nitrogen atoms to gallium atoms is controlled to be 810:1, the temperature in the reaction cavity is controlled to be gradually reduced from 1100 ℃ to 1020 ℃ at the speed of reducing 0.4-0.5 ℃ per second in the growth process, and the growth thickness is D₃High temperature GaN barrier layer of (D)₃＝4nm；

d) reducing the temperature of the reaction cavity to 560 ℃, keeping the pressure of the reaction cavity unchanged, and introducing 21000sccm of NH₃210sccm TEGa, 65sccm SiH₄And 1310sccm TMIn with a growth thickness D₄Low temperature In of_x3Ga_(1-x3)An N well layer with an In doping concentration of 4.2E +20atoms/cm³，D₄＝D₂-12nm, and x₃＝x₂-0.02；

e) Keeping the pressure and temperature of the reaction chamber constant, introducing 160sccm of TMGa and 210L/min of N₂And NH of 6100sccm₃And the molar ratio of nitrogen atoms to gallium atoms is controlled to be 810:1, and the growth thickness D₅Low temperature GaN barrier layer of (D)₅＝1.1D₃；

step 406, growing an AlGaN electron blocking layer on the multi-quantum well layer:

introducing NH of 51000sccm at a reaction cavity temperature of 910 ℃ and a reaction cavity pressure of 250mbar₃TMGa of 35sccm, H of 120L/min₂TMAl of 120sccm, and Cp of 1100sccm₂Growing the AlGaN electron barrier layer on the multi-quantum well layer under the condition of Mg, wherein the thickness of the AlGaN layer is 45nm, and the concentration of Mg doping is 2E19atoms/cm³。

Step 407, growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer:

introducing NH of 51000sccm at a reaction cavity temperature of 9600 ℃ and a reaction cavity pressure of 500mbar₃TMGa of 30sccm, H of 120L/min₂Cp of 1100sccm₂Growing a P-type GaN layer doped with Mg with the thickness of 60nm under the condition of Mg, wherein the Mg doping concentration is 2E19atoms/cm³。

And step 408, cooling:

keeping the temperature at 660 ℃ for 22min, then closing the heating system and the gas supply system, and cooling along with the furnace.

Example 5:

step 501, processing a sapphire substrate:

introducing 125L/min H at 640 deg.C and reaction cavity pressure of 280mbar₂The sapphire substrate was processed for 9 minutes.

Step 502, growing a low-temperature GaN buffer layer on the sapphire substrate, and processing the low-temperature GaN buffer layer to form irregular islands on the low-temperature GaN buffer layer, which comprises the following steps:

1): introducing 19000sccm NH at a temperature of 580 deg.C and a reaction chamber pressure of 560mbar₃TMGa of 90sccm, H of 125L/min₂Growing the low-temperature GaN buffer layer on the sapphire substrate under the condition (1), wherein the thickness of the low-temperature GaN buffer layer is 35 nm;

2) introducing 39000sccm NH into the reaction chamber at 1090 ℃ and 560mbar₃125L/min H₂Under the condition (2), the irregular islands are formed on the low-temperature GaN buffer layer.

Step 503, growing an undoped GaN layer on the low-temperature GaN buffer layer:

introducing 39000sccm NH into the reaction chamber at the temperature of 1190 ℃ and the pressure of 560mbar₃TMGa of 350sccm, H of 125L/min₂Under the condition (2), growing the non-doped GaN layer on the low-temperature GaN buffer layer, wherein the thickness of the non-doped GaN layer is 4 mu m.

Step 504, growing a Si-doped N-type GaN layer on the undoped GaN layer:

keeping the pressure of the reaction cavity at 560mbar and the temperature of the reaction cavity at 1190 ℃, and introducing NH with the flow rate of 59000sccm₃TMGa of 350sccm, H of 125L/min₂And 45sccm of SiH₄Continuously growing Si-doped N-type GaN of 4 μm on the undoped GaN layer, wherein the doping concentration of Si is 9E18atoms/cm³。

Step 505, growing a multiple quantum well layer on the Si-doped N-type GaN layer, the multiple quantum well layer comprising high temperature In_x2Ga_(1-x2)N well layer, high temperature GaN barrier layer, low temperature In_x3Ga_(1-x3)The N-well layer and the low-temperature GaN barrier layer are grown by the following steps:

a) controlling the pressure of the reaction cavity between 270mbar and the temperature of the reaction cavity between 570 ℃, and introducing NH of 29000sccm₃290sccm of TEGa, 80sccm of SiH₄And 1390sccm TMIn grown to a thickness D₁In of Si doped_x1Ga_(1-x1)N is overTransition layer, D₁75nm, with a Si doping concentration reduced by 1E +17atoms/cm per second³At a speed of from 4E +19atoms/cm³Linear ramp down to 2E +19atoms/cm³；

b) Keeping the pressure of the reaction cavity and NH₃The flow rate of (A) and the flow rate of TEGa are not changed, the temperature of the reaction chamber is increased to 1090 ℃, the flow rate of stable TMIn is 1390sccm, and the growth thickness is D₂High temperature In of_x2Ga_(1-x2)An N well layer with an In doping concentration of 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³，D₂95nm, wherein D₂＝1.3D₁，x₁And x₂Are all in the range of 0.26-0.32, and x₂＝x₁+0.01；

c) Keeping the pressure and temperature of the reaction chamber constant, introducing 190sccm of TMGa and 245L/min of N₂And NH of 7500sccm₃The mol ratio of nitrogen atoms to gallium atoms is controlled to be 880:1, the temperature in the reaction chamber is controlled to be gradually reduced from 1100 ℃ to 1020 ℃ at the speed of reducing 0.4-0.5 ℃ per second in the growth process, and the growth thickness is D₃High temperature GaN barrier layer of (D)₃＝6nm；

d) the temperature of the reaction cavity is reduced to 590 ℃, the pressure of the reaction cavity is kept unchanged, NH of 29000sccm is introduced₃290sccm of TEGa, 80sccm of SiH₄And 1390sccm TMIn grown to a thickness D₄Low temperature In of_x3Ga_(1-x3)An N well layer with an In doping concentration of 4E +20-5E +20atoms/cm³，D₄＝D₂-18nm, and x₃＝x₂-0.02；

e) Keeping the pressure and temperature of the reaction chamber constant, introducing 190sccm of TMGa and 200-250L/min of N₂And NH of 7500sccm₃The molar ratio of nitrogen atoms to gallium atoms is controlled to be 880:1, and the growth thickness D₅Low temperature GaN barrier layer of (D)₅＝(1.1-1.3)D₃；

Repeating the above stepsSteps d) and e) periodically growing the low temperature In_x3Ga_(1-x3)The N well layer and the low-temperature GaN barrier layer have the growth cycle number of 5;

step 506, growing an AlGaN electron blocking layer on the multi-quantum well layer:

introducing 65000sccm NH into the reaction chamber at 940 deg.C and 350mbar pressure₃TMGa of 55sccm, H of 125L/min₂TMAl of 125sccm, and Cp of 1280sccm₂Growing the AlGaN electron barrier layer on the multi-quantum well layer under the condition of Mg, wherein the thickness of the AlGaN layer is 55nm, and the concentration of Mg doping is 9E19atoms/cm³。

Step 507, growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer:

introducing 65000sccm NH into the reaction chamber at 9900 deg.C and 850mbar pressure₃TMGa of 90sccm, H of 125L/min₂Cp of 2800sccm₂Growing a P-type GaN layer doped with Mg with the thickness of 180nm under the condition of Mg, wherein the Mg doping concentration is 9E19atoms/cm³。

And step 508, cooling:

keeping the temperature at 670 deg.C for 28min, closing heating system and gas supply system, and cooling with the furnace.

And (3) comparison test:

the contrast test adopts the growth method of the LED epitaxial structure in the prior art:

step 1: introducing 100-130L/min H at the temperature of 620-650 ℃ and the pressure of the reaction cavity of 100-300mbar₂The sapphire substrate was processed for 5 to 10 minutes under the conditions of (1).

Step 2: introducing 10000-20000sccm NH into the reaction chamber at the temperature of 500-600 ℃ and the pressure of 300-600mbar₃TMGa 50-100sccm, H100-130L/min₂Growing the low-temperature buffer layer GaN on the sapphire substrate under the condition (1), wherein the thickness of the low-temperature GaN buffer layer is 20-40 nm;

introducing NH of 30000-40000sccm at the temperature of 1000-1100 ℃ and the pressure of the reaction chamber of 300-600mbar₃、100L/min-130LH of/min₂Under the condition (2), the irregular islands are formed on the low-temperature buffer layer GaN.

And step 3: introducing NH of 30000-40000sccm at the temperature of 1000-1200 ℃ and the pressure of the reaction chamber of 300-600mbar₃200-400sccm TMGa, 100-130L/min H₂Under the conditions of (a), growing the undoped GaN layer; the thickness of the non-doped GaN layer is 2-4 μm.

And 4, step 4: keeping the pressure of the reaction cavity at 300mbar-600mbar, keeping the temperature at 1000 ℃ -1200 ℃, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂And 20sccm to 50sccm SiH₄Continuously growing N-type GaN doped with Si of 3 μm to 4 μm, wherein the doping concentration of Si is 5E18atoms/cm³-1E19atoms/cm³。

And 5: and growing the multi-quantum well layer.

(1) Keeping the pressure in the reaction chamber at 300-400mbar and the temperature at 700-750 ℃, and introducing NH with the flow rate of 50000-70000sccm₃20-40sccm of TMGa, 1500-2000sccm of TMIn, 100-130L/min of N₂Continuously growing In doped with In to a thickness of 2.5-3.5nm_XGa_(1-X)An N-well layer, wherein X is 0.20-0.25;

(2) keeping the pressure in the reaction chamber at 300-400mbar and the temperature at 750-850 ℃, and introducing NH with the flow rate of 50000-70000sccm₃20-100sccm of TMGa, 100-₂Continuously growing a GaN barrier layer with the thickness of 8-15 nm;

periodically and alternately growing In_XGa_(1-X)The total cycle number of the N well layer and the GaN epitaxial layer is 7-15.

Step 6: introducing NH of 50000-70000sccm at the temperature of 900-950 ℃ and the pressure of the reaction chamber of 200-400mbar₃TMGa 30-60sccm, H100-130L/min₂100 TMAl with 130sccm, 1000 Cp with 1300sccm₂Growing the AlGaN electron barrier layer under the condition of Mg, wherein the thickness of the AlGaN layer is 40-60nm, and the Mg doping concentration is 1E19atoms/cm³-1E20atoms/cm³。

And 7: the temperature is 950 ℃ and the pressure of the reaction cavity is 400-900mbar, introducing NH of 50000-₃20-100sccm of TMGa, 100-₂1000-Cp of 3000sccm₂Growing a Mg-doped P-type GaN layer with the thickness of 50-200nm under the condition of Mg, wherein the Mg doping concentration is 1E19atoms/cm³-1E20atoms/cm³。

And 8: keeping the temperature for 20-30min at 650-680 ℃, then closing the heating system and the gas supply system, and cooling along with the furnace.

Samples 1 and 2 were prepared according to the method of the invention in example 3 and the method of the comparative experiment, respectively, with samples 1 and 2 being coated with an ITO layer of about 150nm under the same pre-process conditions, a Cr/Pt/Au electrode of about 1500nm under the same conditions, and a protective layer of SiO under the same conditions₂About 100nm, the sample was then ground and cut under the same conditions into 635 μm by 635 μm (25mil by 25mil) chip particles, and then 100 dies were picked from the same positions of sample 1 and sample 2, respectively, and packaged into a white LED under the same packaging process. The photoelectric properties of sample 1 and sample 2 were tested using an integrating sphere at a drive current of 350 mA.

TABLE 1 comparison of electrical parameters of sample 1 and sample 2

The data obtained by the integrating sphere are analyzed and compared, and as can be seen from table 1, the luminous efficiency of the LED (sample 1) prepared by the LED epitaxial growth method provided by the invention is obviously improved, and the electrical parameters of other LEDs such as voltage, reverse voltage, electric leakage, antistatic capability and the like are improved, because the technical scheme of the application solves the problem that the quantum well luminous radiation composite efficiency of the existing LED is low, the luminous efficiency of the LED is improved, and the photoelectric properties of other LEDs are improved.

The warping degrees BOW value data (um) of the epitaxial wafer samples 1 and 2 are counted, the mean value of the warping degrees of the samples 1 is 5.2um, the mean value of the warping degrees of the samples 2 is 6.4um, the warping degrees of the LED epitaxial wafer samples manufactured by the method are obviously small, and the method can obviously reduce the warping degree of the epitaxial wafer and improve the product percent of pass.

According to the embodiment, the LED epitaxial structure growth method provided by the invention at least realizes the following beneficial effects:

therefore, by the growth method, the luminous efficiency of the LED can be effectively improved, the warping of the epitaxial wafer can be reduced, the yield of the GaN epitaxial wafer is improved, the surface of the epitaxial layer is smooth, and the appearance is better.

Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. A method for growing an LED epitaxial structure is characterized by comprising the following steps:

processing the sapphire substrate;

growing an undoped GaN layer on the low-temperature GaN buffer layer;

growing an N-type GaN layer doped with Si on the undoped GaN layer;

Keeping the pressure of the reaction cavity and NH₃The flow rate of the TEGa is unchanged, the temperature of the reaction chamber is raised to 1000-1400 ℃ and the flow rate of the stable TMIn is 1300-1400sccm,growth thickness of D₂High temperature In of_x2Ga_(1-x2)An N well layer with an In doping concentration of 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³，D₂72-104nm, wherein D₂＝(1.2-1.3)D₁，x₁And x₂Are all in the range of 0.26-0.32, and x₂＝x₁+0.01；

Keeping the pressure and temperature of the reaction chamber constant, introducing 150-200sccm TMGa and 200-250L/min N₂And 6000 plus 8000sccm NH₃The mol ratio of nitrogen atoms to gallium atoms is controlled to be 800:1-900:1, the temperature in the reaction cavity is controlled to be gradually reduced from 1100 ℃ to 1020 ℃ at the speed of reducing 0.4-0.5 ℃ per second in the growth process, and the growth thickness is D₃High temperature GaN barrier layer of (D)₃＝4-6nm；

growing an AlGaN electronic barrier layer on the multi-quantum well layer;

growing a P-type GaN layer doped with Mg on the AlGaN electron blocking layer;

and cooling.

2. The method as claimed in claim 1, wherein the sapphire substrate is processed by introducing 100-₂The sapphire substrate was processed for 5 to 10 minutes under the conditions of (1).

3. The LED epitaxial structure growth method according to claim 1, wherein said growing a low temperature GaN buffer layer on said sapphire substrate and treating said low temperature GaN buffer layer so as to form irregular islands on said low temperature GaN buffer layer, further,

4. The method as claimed in claim 1, wherein the non-doped GaN layer is grown on the low temperature GaN buffer layer by introducing NH of 30000-₃200-400sccm TMGa, 100-130L/min H₂Growing the non-doped GaN layer on the low-temperature GaN buffer layer under the condition (2-4 microns).

5. The LED epitaxial structure growth method of claim 1, wherein the Si-doped N-type GaN layer is grown on the undoped GaN layer, and further, the pressure of the reaction chamber is maintained at 300-600mbar, and the temperature of the reaction chamber is maintainedNH with the flow rate of 30000-₃200-400sccm TMGa, 100-130L/min H₂And 20-50sccm SiH₄Continuously growing Si-doped N-type GaN with the thickness of 3-4 μm on the undoped GaN layer, wherein the doping concentration of Si is 5E18-1E19atoms/cm³。

6. The method as claimed in claim 1, wherein the AlGaN electron blocking layer is grown on the MQW layer, and further NH of 50000-₃TMGa 30-60sccm, H100-130L/min₂100-TMAl of 130sccm, and 1000-Cp of 1300sccm₂Growing the AlGaN electron barrier layer on the multi-quantum well layer under the condition of Mg, wherein the thickness of the AlGaN layer is 40-60nm, and the concentration of Mg doping is 1E19-1E20atoms/cm³。

7. The method as claimed in claim 1, wherein the Mg-doped P-type GaN layer is grown on the AlGaN electron blocking layer by introducing NH of 50000-70000sccm at a reaction chamber temperature of 950-1000 ℃ and a reaction chamber pressure of 400-900mbar₃20-100sccm of TMGa, 100-₂1000-Cp of 3000sccm₂Growing a P-type GaN layer doped with Mg with a thickness of 50-200nm under the condition of Mg, wherein the Mg doping concentration is 1E19-1E20atoms/cm³。

8. The method as claimed in claim 1, wherein the cooling is performed by keeping the temperature at 650-.