CN112436081B - GaN-based LED epitaxial structure for improving carrier injection efficiency and growth method thereof - Google Patents

GaN-based LED epitaxial structure for improving carrier injection efficiency and growth method thereof Download PDF

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CN112436081B
CN112436081B CN202011195588.2A CN202011195588A CN112436081B CN 112436081 B CN112436081 B CN 112436081B CN 202011195588 A CN202011195588 A CN 202011195588A CN 112436081 B CN112436081 B CN 112436081B
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程立文
李侦伟
林星宇
曾祥华
杨达
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Yangzhou University
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Abstract

The invention discloses a GaN-based LED epitaxial structure for improving carrier injection efficiency and a growth method thereof, wherein a light-emitting layer is formed by alternating barrier layers and quantum well layers, wherein according to the growth sequence, the last barrier layer adopts Al components, namely Al with the x value gradually changed from 0to 0.15 x Ga x1‑N barrier layer, other barrier layers are GaN barrier layers, and In is used as sub-well layer y Ga y1‑An N quantum well layer is formed on the substrate,y0.1 to 0.3. The method removes the grown AlGaN electron blocking layer, can reduce the improvement of a hole barrier caused by p-type Mg doped AlGaN, simultaneously reduces serious lattice defects and larger stress caused by the growth of AlGaN, reduces the high-temperature damage of the high-temperature growth condition to a light-emitting layer structure, improves the chip quality, and adopts Al with gradually changed Al components x Ga ‑x1The last layer of the N barrier layer can still effectively improve the function of an electron barrier, and can also effectively reduce a hole barrier, thereby inhibiting electron leakage and further improving the hole injection capability, further improving the effective radiation recombination rate in a light-emitting layer and improving the light-emitting efficiency of the GaN-based LED.

Description

GaN-based LED epitaxial structure for improving carrier injection efficiency and growth method thereof
Technical Field
The invention relates to the field of LED design and application, in particular to an LED epitaxial layer structure with improved hole injection layer and luminescent layer structures and a growth method thereof.
Background
The GaN-based LED is one of the main light sources for forming white light at present, and has the advantages of long service life and low energy consumption, but along with the requirement of working environment, the GaN-based LED is increasingly required to work under a large current, and along with this, the GaN-based LED generates a large efficiency attenuation under the large current. Electron leakage is an important cause of efficiency degradation in current research because hole injection from the p-type layer to the active region is much less efficient than electron injection from the n-type layer due to the higher effective mass of holes relative to electrons, and thus a large number of carriers accumulate in the last quantum well near the p-type layer, resulting in most of the electrons leaking to the p-type layer.
In contrast, in the current GaN-based LED epitaxial growth method, a method of growing an AlGaN electron blocking layer is adopted to effectively increase the height of an effective potential barrier of an energy band on the p side of a light emitting layer, and electron leakage can be effectively suppressed through energy band engineering, but at the same time, a hole potential barrier brought by the AlGaN electron blocking layer also reduces injection of holes from a p electrode to the light emitting layer to a certain extent, which limits improvement of the light emitting efficiency of the GaN-based LED; on the other hand, p-type Mg doping activation rate in the AlGaN electron blocking layer is low, and serious lattice defects and large stress which occur with the increase of Al composition can distort the energy band of the light emitting layer, thereby further limiting the ability of injecting holes into the light emitting layer.
However, in order to meet the requirement of high photoelectric efficiency of GaN-based LEDs during operation, an AlGaN electron blocking layer is still grown in epitaxial growth in the industry, so as to avoid the occurrence of a low electron barrier in the energy band of a light emitting layer due to the absence of a p-AlGaN layer, which further causes a large amount of electron leakage, thereby causing severe photoelectric efficiency attenuation.
Disclosure of Invention
In order to effectively reduce the problem of efficiency reduction of the GaN-based LED, the invention provides a GaN-based LED epitaxial structure for improving carrier injection efficiency and a growth method thereof.
The technical solution for realizing the purpose of the invention is as follows: a light-emitting layer of GaN-based LED epitaxial structure for improving carrier injection efficiency is composed of barrier layers and quantum well layers alternately, wherein in growth sequence, the last barrier layer adopts Al with Al component, i.e. Al with x value gradually changed from 0to 0.15 x Ga x1-An N barrier layer.
Preferably, Al x Ga x1-The thickness of the N barrier layer is 8 nm-15 nm.
Preferably, the quantum well layer adopts In y Ga y1-An N quantum well layer is formed on the substrate,y0.1-0.3, and the thickness of each quantum well layer is 2 nm.
Preferably, the other barrier layers except the last barrier layer are GaN barrier layers, and the thickness of the GaN barrier layers is 8 nm-15 nm.
A GaN-based LED epitaxial structure for improving carrier injection efficiency sequentially comprises a substrate, a low-temperature nucleation layer GaN, an undoped u-GaN layer, a Si-doped n-GaN layer, an improved light emitting layer and a p-GaN layer from bottom to top.
A method for growing a light emitting layer of a GaN-based LED epitaxial structure for improving carrier injection efficiency comprises the following steps:
(1) the pressure of a reaction cavity is 100 Torr-500 Torr, the temperature is 800 ℃ to 950 ℃, and the MO sources are TEGa, TMIn and SiH4Growing a GaN barrier layer;
(2) the pressure of a reaction cavity is 100 Torr-500 Torr, the temperature is 700 ℃ -800 ℃, and TEGa, TMIn and SiH are used4As MO source, In doped with In is grown y Ga 1-y An N quantum well layer;
(3) alternately performing the step (1) and the step (2) to alternately grow In y Ga -y1An N/GaN light emitting layer;
(4) the pressure of the reaction chamber is kept at 200 Torr-500 Torr, the temperature is kept at 900 ℃ -1100 ℃, and N is kept2Introducing MO source of TMAl, TMGa and NH under the atmosphere4In y Ga 1-y Growth on N-quantum well layerxAl graded from 0to 0.15 in growth direction x Ga x1-An N barrier layer.
In the invention, the last GaN barrier layer in the light-emitting layer is replaced by Al with the same thickness and the Al component gradually changed from 0to 0.15 along the growth direction x Ga x1-The N barrier layer and the grown AlGaN electron barrier layer are removed, so that the method has the following advantages:
(1) the growth AlGaN electron blocking layer is removed, so that the improvement of a hole barrier caused by p-type Mg doped AlGaN can be reduced, the serious lattice defect and larger stress caused by the growth AlGaN are reduced, the high-temperature damage of the high-temperature growth condition to the light-emitting layer structure is reduced, and the chip quality is improved.
(2) Al with gradually changed Al component x Ga -x1The last layer of the N barrier layer can still effectively improve the function of an electron barrier, and can also effectively reduce a hole barrier, thereby inhibiting electron leakage and further improving the hole injection capability, further improving the effective radiation recombination rate in a light-emitting layer and improving the light-emitting efficiency of the GaN-based LED.
Drawings
Fig. 1 is an energy band diagram of a general GaN-based LED.
FIG. 2 is Al whose Al composition is gradually changed from 0to 0.15 without removing the electron blocking layer x Ga x1-Energy band diagram of GaN-based LED of N barrier layer.
FIG. 3 shows Al of the present invention with a gradual change from 0to 0.15 in Al composition for removing the electron blocking layer x Ga x1-The GaN-based LED of the N barrier layer has an energy band diagram.
Fig. 4 is a schematic view of a preparation flow of the epitaxial growth method of the GaN-based LED according to the present invention.
FIG. 5 shows Al in the example of the present invention x Ga x1-N /In y Ga -y1N /……/In y Ga -y1The structure of the N/GaN light-emitting layer is schematically shown.
Detailed Description
The invention replaces the last GaN barrier layer in the traditional luminous layer with Al with the Al component gradually changed from 0to 0.15 x Ga x1-And the AlGaN electron blocking layer in the traditional epitaxial structure is removed after the epitaxial structure is formed.
The invention designs the last barrier layer in the luminous layer as Al with the Al component gradually changed from 0to 0.15 x Ga x1-The N barrier layer, on the one hand, the removal of the AlGaN electron blocking layer can be effectively reducedDamage to the luminescent layer during growth of the highly doped AlGaN layer, and on the other hand, Al with gradually changed Al component is adopted x Ga x1-The N barrier layer can greatly optimize the energy band height, greatly inhibit electron leakage and effectively improve the injection of holes from the p electrode to the light-emitting layer. Thereby effectively improving the photoelectric performance of the GaN-based LED.
As can be seen from FIGS. 1, 2 and 3, Al having a gradually changed Al composition is used x Ga 1-x The N barrier layer is used as the last barrier layer, the effect of effectively improving an electron barrier can be still realized, meanwhile, a hole barrier can be effectively reduced, electron leakage is inhibited, and hole injection capability is further improved, so that the effective radiation recombination rate in a light-emitting layer is improved, and the light-emitting efficiency of the GaN-based LED is improved.
With reference to fig. 4, the method for growing the epitaxial structure of the GaN-based LED according to the present invention is as follows:
VEECO MOCVD is used to grow high brightness GaN base LED epitaxial wafer. Using high-purity H2Or high purity N2Or high purity H2And high purity N2As a carrier gas, high purity NH3（NH399.999%) as an N source, a metal-organic source of trimethyl gallium (TMGa) and a metal-organic source of triethyl gallium (TEGa), trimethyl indium (TMIn) as an indium source, and an N-type dopant of Silane (SiH)4) Trimethylaluminum (TMAl) as the aluminum source and magnesium diclomelate (CP) as the P-type dopant2Mg), the substrate is (0001) plane sapphire, the reaction pressure is between 100 Torr and 1000 Torr, and the specific growth process is as follows:
101, annealing the sapphire substrate in a hydrogen atmosphere at 1050-1150 ℃, and cleaning the surface of the substrate.
102, introducing ammonia gas and TMGa at the temperature of 500-610 ℃ and the pressure of a reaction cavity of 400-650 Torr, and growing a low-temperature nucleation layer GaN with the thickness of 20-40 nm on a sapphire substrate;
103, keeping the pressure of a reaction cavity at 1050-1200 ℃ to be 100-500 Torr, introducing ammonia gas and TMGa, and continuously growing an undoped u-GaN layer with the thickness of 1-3 mu m on the low-temperature nucleation layer GaN.
104, keeping the pressure of the reaction cavity at 1050-1200 ℃ to be 100-600 Torr, and introducing ammonia gas, TMGa and SiH4Continuously growing a Si-doped n-GaN layer with stable Si doping concentration and thickness of 2-4 μm on the undoped u-GaN layer, wherein the Si doping concentration is 8 multiplied by 1018 atoms/cm3~2×1019atoms/cm3。
105, with reference to FIG. 5, maintaining the pressure of the reaction chamber at 100 Torr to 500Torr at a temperature of 800 ℃ to 950 ℃, using TEGa, TMIn and SiH as MO sources4Growing a GaN barrier layer 61 with the thickness of 8nm to 15nm on the Si-doped n-GaN layer; the temperature of the reaction chamber is 100 Torr-500 Torr, the temperature is 700 ℃ to 800 ℃, and TEGa, TMIn and SiH are used4As the MO source, In doped In was grown on the GaN barrier layer 61 to a thickness of 2nm y Ga 1-y The N quantum well layer 60 is formed,y0.1 to 0.3; repeatedly growing GaN barrier layer and then repeatedly growing In y Ga 1-y N quantum well layer, alternately grown In y Ga -y1N/GaN light emitting layer for controlling In y Ga 1-y The growth period of the N quantum well layer is 5 until a part of the light emitting layer is obtained.
106, and combining with the figure 5, keeping the pressure of the reaction chamber at 200 Torr-500 Torr, the temperature at 900 ℃ -1100 ℃, and N2Introducing MO sources of TMAl, TMGa and NH4 under the atmosphere, and forming a final layer of In y Ga 1-y Continuously growing a P-type Al component with the thickness of 8 nm-15 nm on the N quantum well layerxAl graded from 0to 0.15 in growth direction x Ga -x1An N barrier layer 62;
107, keeping the pressure of the reaction cavity at 100 Torr-500 Torr and the temperature at 850 ℃ -1050 ℃, and introducing MO sources of TEGa and CP2Mg in Al x Ga -x1A Mg-doped P-type GaN contact layer (P-type GaN layer) having a thickness of 200 nm was continuously grown on the N-barrier layer 62, and the Mg doping concentration was 1X 1019 atoms/cm3~1×1022 atoms/cm3；
And 108, after the epitaxial growth is finished, reducing the reaction temperature to 650-800 ℃, annealing for 5-10 min in a pure nitrogen atmosphere, and then reducing the temperature to room temperature to finish the growth.
Sample 1 prepared by the method described in example 1, i.e., the growth method of the present invention, and sample 2 grown by the method described in example 2, and sample 3 grown by the method described in example 3 are described below, respectively.
Example 1
The light emitting layer in the epitaxial structure of this embodiment is shown in fig. 5, and the growth method is shown in fig. 4. The specific growth mode is as follows:
step 101, processing a substrate:
and annealing the sapphire substrate in a hydrogen atmosphere at the temperature of 1100 ℃, and cleaning the surface of the substrate.
Step 102, growing a low-temperature nucleation layer GaN:
at 550 ℃, the pressure of a reaction cavity is 500Torr, ammonia gas and TMGa are introduced, and a low-temperature nucleation layer GaN with the thickness of 30nm is grown on the sapphire substrate.
Step 103, growing an undoped n-GaN layer:
at 1100 ℃, the pressure of the reaction chamber was kept at 500Torr, and ammonia gas and TMGa were introduced to continue growing the undoped u-GaN layer with a thickness of 2 μm.
Step 104, growing a Si-doped n-GaN layer:
at 1100 ℃, the pressure of the reaction chamber is kept at 500Torr, and ammonia gas, TMGa and SiH are introduced4Continuously growing a Si-doped n-GaN layer with a stable doping concentration and a thickness of 3 μm, wherein the doping concentration of Si is 1 × 1019atoms/cm3。
Step 105, growing a light emitting layer on the part:
maintaining the pressure of a reaction cavity at the temperature of 900 ℃ and the pressure of 300 Torr, and growing a GaN barrier layer with the thickness of 15nm by using an MO source of TEGa, TMIn and SiH 4;
in a reaction chamber at a pressure of 300 Torr and a temperature of 750 ℃ using TEGa, TMIn and SiH4As MO source, In doped with In and having a thickness of 2nm was grownyGa1-yAn N quantum well layer, y is 0.2;
is repeatedly usedA long GaN barrier layer, and then repeating InyGa1-yGrowth of N Quantum well layer, alternatively growing InyGa1-yN/GaN partial light emitting layer for controlling InyGa1-yThe growth period of the N quantum well layer was 6.
106, growing Al with gradually changed Al componentsxGa1-xN last barrier layer:
the pressure in the reaction chamber was maintained at 200 Torr and the temperature at 1100 deg.C, N2Introducing MO source TMAl, TMGa and NH4 In an atmosphereyGa1-yLast In layer of N/GaN partial luminous layeryGa1-yContinuously growing P-type Al with gradually changed composition on the N quantum well layer and the thickness of 12nmxGa1-xThe N barrier layer is used as the last barrier layer of the light-emitting layer, wherein x is gradually changed from 0to 0.15 along the growth direction.
Step 107, growing a P-type GaN contact layer:
keeping the pressure of the reaction cavity at 500Torr and the temperature at 1000 ℃, and introducing MO sources of TEGa and CP2Mg, Al with gradually changed Al composition in the last barrier layerxGa1-xContinuously growing a P-type GaN contact layer with a thickness of 200 nm and a Mg doping concentration of 1 × 10 on the N barrier layer21 atoms/cm3；
Step 108, cooling:
and after the epitaxial growth is finished, reducing the reaction temperature to 750 ℃, annealing for 10 min in a pure nitrogen atmosphere, then reducing the temperature to room temperature, and finishing the growth to obtain a sample 1.
The invention adopts Al with gradually changed Al componentxGa1-xThe last barrier layer of the N barrier layer effectively improves the hole injection probability and reduces the electron leakage probability, thereby reducing the problem of efficiency reduction.
Example 2
The specific growth mode is as follows:
step 201, processing a substrate:
and annealing the sapphire substrate in a hydrogen atmosphere at the temperature of 1100 ℃, and cleaning the surface of the substrate.
Step 202, growing a low-temperature nucleation layer GaN:
at 550 ℃, the pressure of a reaction cavity is 500Torr, ammonia gas and TMGa are introduced, and a low-temperature nucleation layer GaN with the thickness of 30nm is grown on the sapphire substrate.
Step 203, growing an undoped n-GaN layer:
at 1100 ℃, the pressure of the reaction chamber was kept at 500Torr, and ammonia gas and TMGa were introduced to continue growing the undoped u-GaN layer with a thickness of 2 μm.
Step 204, growing a Si-doped n-GaN layer:
at 1100 deg.C, the pressure in the reaction chamber was maintained at 500Torr, and ammonia gas, TMGa and SiH were introduced4Continuously growing a Si-doped n-GaN layer with a thickness of 3 μm and a stable doping concentration, wherein the doping concentration of Si is 1 × 1019atoms/cm3。
Step 205, growing a light emitting layer on the part:
maintaining the pressure of a reaction cavity at the temperature of 900 ℃ and the pressure of 300 Torr, and growing a GaN barrier layer with the thickness of 15nm by using an MO source of TEGa, TMIn and SiH 4;
in a reaction chamber at a pressure of 300 Torr and a temperature of 750 ℃ using TEGa, TMIn and SiH4As MO source, In doped with In and having a thickness of 2nm was grownyGa1-yAn N quantum well layer, y is 0.2;
repeatedly growing GaN barrier layer and then repeating InyGa1-yGrowth of N Quantum well layer, alternatively growing InyGa1-yN/GaN partial light emitting layer for controlling InyGa1-yThe growth period of the N quantum well layer was 6.
Step 206, growing Al with gradually changed Al componentxGa1-xN last barrier layer:
the pressure in the reaction chamber was maintained at 200 Torr and the temperature at 1100 deg.C, N2Introducing MO source TMAl, TMGa and NH4 In an atmosphereyGa1-yLast In layer of N/GaN partial luminous layeryGa1-yContinuously growing P-type Al with gradually changed composition on the N quantum well layer and the thickness of 12nmxGa1-xThe N barrier layer is used as the last barrier layer of the light-emitting layer, wherein x is gradually changed from 0to 0.15 along the growth direction.
Step 207, growing a P-type AlGaN electron blocking layer:
the pressure of the reaction cavity is kept at 200 Torr and 1100 ℃, and MO sources TMA1, TMGa and CP are introduced2Mg, Al with a graded Al composition on the last barrier layerxGa1-xContinuously growing a 200 nm-thick P-type AlGaN electron blocking layer on the N barrier layer for 100 min, wherein the molar composition of Al is 20%, and the doping concentration of Mg is 1 multiplied by 1021 atoms/cm3。
Step 208, growing a P-type GaN contact layer:
keeping the pressure of the reaction cavity at 500Torr and the temperature at 1000 ℃, and introducing MO sources of TEGa and CP2Mg is continuously grown on the P-type AlGaN electron barrier layer, namely a P-type GaN contact layer with the thickness of 200 nm and the Mg doping concentration of 1 multiplied by 1021 atoms/cm3；
Step 209, cooling:
and after the epitaxial growth is finished, reducing the reaction temperature to 750 ℃, annealing for 10 min in a pure nitrogen atmosphere, then reducing the temperature to room temperature, and finishing the growth to obtain a sample 2.
Example 3
The embodiment adopts a traditional epitaxial growth method of a GaN-based LED, and specifically comprises the following steps:
step 301, processing the substrate:
and annealing the sapphire substrate in a hydrogen atmosphere at the temperature of 1100 ℃, and cleaning the surface of the substrate.
Step 302, growing a low-temperature nucleation layer GaN:
at 550 ℃, the pressure of a reaction cavity is 500Torr, ammonia gas and TMGa are introduced, and a low-temperature nucleation layer GaN with the thickness of 30nm is grown on the sapphire substrate.
Step 303, growing an undoped n-GaN layer:
at 1100 ℃, the pressure of the reaction chamber was kept at 500Torr, and ammonia gas and TMGa were introduced to continue growing the undoped u-GaN layer with a thickness of 2 μm.
Step 304, growing a Si-doped n-GaN layer:
at 1100 ℃, keeping the pressure of the reaction cavity at 500Torr, introducing ammonia gas and TMGaAnd SiH4Continuously growing a Si-doped n-GaN layer with a stable doping concentration and a thickness of 3 μm, wherein the doping concentration of Si is 1 × 1019atoms/cm3。
Step 305, growing a conventional light emitting layer:
maintaining the pressure of a reaction cavity at the temperature of 900 ℃ and the pressure of 300 Torr, and growing a GaN barrier layer with the thickness of 15nm by using an MO source of TEGa, TMIn and SiH 4;
in a reaction chamber at a pressure of 300 Torr and a temperature of 750 ℃ using TEGa, TMIn and SiH4As MO source, In doped with In and having a thickness of 2nm was grownyGa1-yAn N quantum well layer, y is 0.2;
repeatedly growing GaN barrier layer and then repeating InyGa1-yGrowth of N Quantum well layer, conventional In growth alternatelyyGa1-yN/GaN light emitting layer for controlling InyGa1-yThe growth period of the N quantum well layer is 6, and the GaN barrier layer is taken as the traditional InyGa1-yAnd the last barrier layer of the N/GaN light-emitting layer.
Step 306, growing a P-type AlGaN electron blocking layer:
the pressure of the reaction cavity is kept at 200 Torr and 1100 ℃, and MO sources TMA1, TMGa and CP are introduced2Mg InyGa1-yContinuously growing a 200 nm-thick P-type AlGaN electron blocking layer on a GaN barrier layer of the N/GaN light-emitting layer for 100 min, wherein the molar component of Al is 20%, and the Mg doping concentration is 1 multiplied by 1021 atoms/cm3。
Step 307, growing a P-type GaN contact layer:
keeping the pressure of the reaction cavity at 500Torr and the temperature at 1000 ℃, and introducing MO sources of TEGa and CP2Mg is continuously grown on the P-type AlGaN electron barrier layer, namely a P-type GaN contact layer with the thickness of 200 nm and the Mg doping concentration of 1 multiplied by 1021 atoms/cm3；
Step 308, cooling:
and after the epitaxial growth is finished, reducing the reaction temperature to 750 ℃, annealing for 10 min in a pure nitrogen atmosphere, then reducing the temperature to room temperature, and finishing the growth to obtain a sample 3.
Sample 1 differs from sample 2 in that: sample 2 has one more P-type AlGaN electron blocking layer than sample 1, and sample 2 differs from sample 3 in that: the last barrier layer in the light-emitting layer of sample 2 is made of Al with a gradually changed Al compositionxGa1-xThe N barrier layer, and the last barrier layer in the light emitting layer of sample 3 was a conventional GaN barrier layer.
After the samples 1, 2 and 3 are measured, according to the definition of the efficiency attenuation, the efficiency attenuation is the ratio of the maximum IQE minus the IQE at the current operating current to the maximum IQE, the efficiency attenuation of the conventional LED sample 3 is 57.1%, the efficiency attenuation of the sample 2 is 44.9%, and the efficiency attenuation of the sample 1 designed by the invention is only 25.6%.
This shows that the epitaxial growth method of GaN-based LED containing Al-component gradient material provided by the invention can effectively reduce the efficiency attenuation of GaN-based LED, and 0to 0.15 is the better Al component distribution.

Claims (4)

1. The GaN-based LED epitaxial structure is characterized In that the epitaxial structure does not comprise an AlGaN electronic barrier layer, and sequentially comprises a low-temperature nucleation layer GaN, an undoped u-GaN layer, a Si-doped n-GaN layer, a light-emitting layer and a p-GaN layer from bottom to top, wherein the light-emitting layer is alternately composed of a barrier layer and a quantum well layer, and the quantum well layer adopts In y Ga y1-An N quantum well layer is formed on the substrate,y0.1-0.3, wherein the last barrier layer adopts Al with the Al component, namely the Al with the x value gradually changing from 0to 0.15 according to the growth sequence x Ga x1-N barrier layer, other barrier layers being GaN barrier layers, Al x Ga x1-The thickness of the N barrier layer is 8 nm-15 nm.
2. The GaN-based LED epitaxial structure of claim 1, wherein the number of quantum well layers is at least 2, and each quantum well layer has a thickness of 2 nm.
3. The GaN-based LED epitaxial structure of claim 1, wherein the GaN barrier layer has a thickness of 8nm to 15 nm.
4. A growth method of the epitaxial structure of GaN-based LED according to any of claims 1 to 3, wherein the light emitting layer is prepared by the steps of:
(1) the pressure of a reaction cavity is 100 Torr-500 Torr, the temperature is 800 ℃ to 950 ℃, and the MO sources are TEGa, TMIn and SiH4Growing a GaN barrier layer;
(2) the pressure of a reaction cavity is 100 Torr-500 Torr, the temperature is 700 ℃ -800 ℃, and TEGa, TMIn and SiH are used4As MO source, In doped with In is grown y Ga 1-y An N quantum well layer;
(3) alternately performing the step (1) and the step (2) to alternately grow In y Ga -y1An N/GaN light emitting layer;
(4) the pressure of the reaction chamber is kept at 200 Torr-500 Torr, the temperature is kept at 900 ℃ -1100 ℃, and N is kept2Introducing MO source of TMAl, TMGa and NH under the atmosphere4In y Ga -y1In of N/GaN light emitting layer y Ga 1-y Growth on N-quantum well layerxAl graded from 0to 0.15 in growth direction x Ga x1-An N barrier layer.
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