CN103346219A - Growing method for duplex multi-quantum well luminescent layer structure and LED epitaxial structure - Google Patents

Abstract

The present invention provides a method for growing a composite multi-quantum well light-emitting layer structure and a corresponding LED epitaxial structure. The well light-emitting layer of the epitaxial structure includes 6-8 unit layers, and each unit layer includes from bottom to top: A well layer, a second well layer, a first epitaxial layer, a first well layer, a second well layer, and a second epitaxial layer. The present invention adopts the compound multi-quantum well to improve the separation of the wave function of the traditional multi-quantum well due to the stress of the epitaxial layer, and improves the situation that the hole concentration of the well layer is too low due to the width of the epitaxial layer of the traditional multi-quantum well; the LED chip is improved. The internal quantum well efficiency is obtained, macroscopically improving the brightness of small and medium-sized LED chips, and improving the light efficiency of large-sized LED chips.

Description

Growth method of compound multi-quantum well light-emitting layer structure and LED epitaxial structure

technical field

The invention relates to the technical field of LED epitaxial design, in particular to a method for growing a compound multi-quantum well light-emitting layer structure and a corresponding LED epitaxial structure. the

Background technique

In the LED market, large-size and high-power 30mil*30mi chips are mostly used for street lighting, and small and medium-sized 12mil*28mil chips are mostly used for backlighting. The quality of the products is related to the brightness of the chip. Therefore, the brightness of chips of various sizes has become the focus of packaging customers. the

At present, there are many kinds of epitaxial growth methods to improve the light efficiency of large size and the brightness of small and medium size. Most of the structural innovations lie in the P-type layer, such as:

(1) The P layer adds PAlGaN/PInGaN, PAlGaN/PGaN, PAlGaN/GaN and other superlattice structures to improve the current expansion ability to improve the brightness;

(2) Change the doping method of Mg in the P layer, etc. to increase the ionization rate of Mg, and increase the hole concentration to achieve the purpose of improving light efficiency and brightness. the

Contents of the invention

The purpose of the present invention is to provide a growth method of a complex multi-quantum well light-emitting layer structure and a corresponding LED epitaxial structure, so as to solve the technical problem of insufficient brightness of the current LED chip. the

In order to achieve the above object, the invention provides a method for growing a compound multi-quantum well light-emitting layer structure, comprising the following steps:

A. Control the temperature at 710-750°C, control the pressure of the reaction chamber at 300-400mbar, and feed In at a flow rate of 1500-1700sccm, and grow In _x Ga _(1-x) N wells of 2.7-3.5nm doped with In layer, x=0.20-0.22;

B. Keep the temperature and pressure constant, the flow rate of In is 300-450sccm, grow In _z Ga _(1-z) N well layer of 0.5-1.0nm doped with In, z=0.04-0.08,

C. Keep the pressure constant, raise the temperature to 810-840°C, feed Al at a flow rate of 30-50 sccm, and feed In at a flow rate of 800-1000 sccm, and grow 4-6nm Al and In-doped Al _x1 In _x2 Ga _(1-x1-x2) N epitaxy layer, x ₁ =0.04-0.05, x ₂ =0.10-0.12;

D. Repeat steps A and B;

E. Keep the pressure constant, and raise the temperature to 810-840°C to grow a 10-12nm GaN epitaxial layer;

F. Repeat steps A, B, C, D, and E 6-8 times until the overall thickness of the light-emitting layer of the well reaches 162-216 nm. the

Preferably, said step A includes steps before:

S1. Under a hydrogen atmosphere at 1000-1100°C, the reaction chamber pressure is 150-200mbar, and the sapphire substrate is processed for 4-5 minutes;

S2. Lower the temperature to 540-570°C, control the pressure of the reaction chamber at 450-600mbar, and grow a low-temperature buffer layer GaN with a thickness of 30-50nm on the sapphire substrate;

S3. Increase the temperature to 950-1050°C, control the pressure of the reaction chamber at 450-600mbar, and continue to grow 2.5-3.0um undoped GaN;

S4. Keep the temperature constant, control the pressure of the reaction chamber at 200-400mbar, then continue to grow 3.5-4.5μm Si-doped N-type GaN, and control the Si doping concentration at 8E+18-1E19atom/cm ³ .

Preferably, steps are included after the step F:

D1. Raise the temperature to 900-950°C, control the pressure of the reaction chamber at 150-300mbar, and continue to grow a 30-40nm P-type In _y Al _(1-y) GaN layer doped with Al and In, y=0.08-0.12;

D2. Raise the temperature to 1000-1100°C, control the pressure of the reaction chamber at 200-600mbar, and continue to grow a 60-90nm Mg-doped P-type GaN layer, and control the Mg doping concentration at 3E+18-4E18atom/cm ³ ;

D3. Cool down to 650-700°C, keep warm for 20-30 minutes, and cool in the furnace. the

The present invention also discloses an LED epitaxial structure, the light-emitting well layer of the LED epitaxial structure includes 6-8 unit layers, and each unit layer sequentially includes from bottom to top:

The first well layer, the first well layer is an In _x Ga _(1-x) N well layer doped with 2.7-3.5nmIn, x=0.20-0.22;

a second well layer, the second well layer is an In _z Ga _(1-z) N well layer doped with 0.5-1.0nmIn, z=0.04-0.08;

The first epitaxial layer, the first epitaxial layer is Al _x1 In _x2 Ga _(1-x1-x2) N epitaxial layer doped with 4-6nm Al and In, x ₁ =0.04-0.05, x ₂ =0.10- 0.12;

The first well layer, the first well layer is an In _x Ga _(1-x) N well layer doped with 2.7-3.5nmIn, x=0.20-0.22;

a second well layer, the second well layer is an In _z Ga _(1-z) N well layer doped with 0.5-1.0nmIn, z=0.04-0.08;

The second epitaxial layer, the second epitaxial layer is a 10-12nm GaN epitaxial layer. the

Preferably, the unit layer includes from bottom to top:

Low temperature buffer GaN layer with a thickness of 30-50nm;

Undoped GaN layer with a thickness of 2.5-3.0um;

The N-type GaN layer has a thickness of 3.5-4.5 μm and is doped with Si, and the doping concentration of Si is controlled to be 8E+18-1E19atom/cm ³ .

Preferably, the unit layer includes from bottom to top:

P-type AlGaN layer, P-type In _y Al _(1-y) GaN layer with a thickness of 30-40nm, y=0.08-0.12;

The P-type GaN layer has a thickness of 60-90nm and is doped with Mg, and the doping concentration of Mg is controlled to be 3E+18-4E18atom/cm ³ .

The present invention has the following beneficial effects:

1. Increase the light extraction efficiency per unit area: The lattice mismatch between the traditional multi-quantum well layer and the epitaxial layer and the relatively thick epitaxial layer lead to the existence of polarization and compressive stress, which leads to the wave of electrons and holes in the well layer microscopically. Function separation, electron and hole recombination efficiency is poor, and the number of photons generated per unit time and unit area is small; and the unit layer structure set by the present invention makes the transition layer (multiple composite well layers) adjust the lattice of InGaN and GaN Matching makes the stress between the well layer and the epitaxial layer smaller, the wave functions of electrons and holes are more concentrated, and the recombination probability of electrons and holes is increased. the

2. Increase the hole concentration of the well layer: the thickness of the traditional multi-quantum well epitaxial layer is about 10-12nm. Due to the relatively wide potential barrier, the propagation of holes injected by the P layer in the traditional multi-quantum well is limited; Invented that the first epitaxial layer is AlInGaN quaternary growth. By adjusting the composition of Al and In, the lattice of the epitaxial layer is close to that of the well layer, which reduces the influence of the epitaxial layer on the stress of the well layer. The thickness of the first epitaxial layer It is controlled at 4-6nm, which is smaller than the thickness of the traditional epitaxial layer, which is conducive to the propagation of holes injected into the P layer in the compound quantum well, and increases the hole concentration of the first well layer and the second well layer. the

The compound multi-quantum well layer of the invention improves the separation of wave functions of traditional multi-quantum wells due to well epitaxy layer stress, and improves the situation of too low hole concentration in well layers of traditional multi-quantum wells due to epitaxial width. Through the above improvements, the internal quantum well efficiency of the LED chip is improved, objectively improving the brightness of small and medium sizes, and improving the light efficiency of large sizes. the

In addition to the objects, features and advantages described above, the present invention has other objects, features and advantages. Hereinafter, the present invention will be described in further detail with reference to the drawings. the

Description of drawings

The accompanying drawings constituting a part of this application are used to provide further understanding of the present invention, and the schematic embodiments and descriptions of the present invention are used to explain the present invention, and do not constitute an improper limitation of the present invention. In the attached picture:

Fig. 1 is a structural schematic diagram of an existing LED epitaxial structure;

Fig. 2 is the structural representation of the LED epitaxy structure of preferred embodiment of the present invention;

Figure 3 is a schematic diagram of the energy band structure of the existing LED epitaxial structure; Figure (a) is a schematic diagram of the conduction band energy level; Figure (b) is a schematic diagram of the valence band energy level;

Figure 4 is a schematic diagram of the energy band structure of a preferred embodiment of the present invention; Figure (a) is a schematic diagram of the conduction band energy level; Figure (b) is a schematic diagram of the valence band energy level;

Fig. 5 is a comparison chart of photoelectric performance data points of sample 1 and sample 2;

Fig. 6 is a comparison chart of photoelectric performance data points of sample 3 and sample 4;

Among them, 1. P-type GaN layer; 2. P-type InAlGaN layer, 3-1, multi-quantum epitaxial layer, 3-2, multi-quantum well layer, 4. N-type GaN, 5. U-type GaN; 3-A, First well layer, 3-B, second well layer, 3-C, first epitaxial layer, 3-D, second epitaxial layer; 6, P-type AlGaN layer, 7, low-temperature buffer GaN layer, 8, undoped Doped GaN layer. the

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention can be implemented in various ways defined and covered by the claims. the

The comparative example 1 of sample 1 prepared by the existing traditional method and the example 1 of sample 2 prepared by the growth method of the present invention are respectively described below, and then the two methods are used to obtain sample 1 and sample 2 for performance testing and comparison. the

Comparative example one,

1. Under the hydrogen atmosphere of 1000-1100℃, the pressure of the reaction chamber is controlled at 150-200mbar, and the sapphire substrate is treated at high temperature for 4-5 minutes;

2. Lower the temperature to 540-570°C, control the pressure of the reaction chamber at 450-600mbar, and grow a low-temperature buffer layer GaN with a thickness of 30-50nm on the sapphire substrate;

3. Raise the temperature to 950-1050°C, control the pressure of the reaction chamber at 450-600mbar, and continue to grow 2.5-3.0um undoped GaN;

4. Keep the temperature constant, control the pressure of the reaction chamber at 200-400mbar, and then grow 3.5-4.5μm N-type GaN continuously doped with silicon;

5. Cool down to 710-840°C, control the pressure of the reaction chamber at 300-400mbar, and grow the multi-quantum well light-emitting layer periodically. Single-cycle growth method: (1) Cool down to 710-750°C to grow In-doped 2.7-3.5 nm In _x Ga _(1-x) N (x=0.20-0.22) well layer, (2) raise the temperature to 810-840°C to grow a 10-12nm GaN epitaxial layer, and then take (1) (2) as a cycle Perform repeated growth, the number of repeated growth cycles is 13-15, and the overall thickness is controlled at 165-233nm;

6. Then raise the temperature to 900-950°C, control the pressure of the reaction chamber at 150-300mbar, and continue to grow a 30-40nm P-type In _y Al _(1-y) GaN layer doped with indium and aluminum, y=0.08-0.12;

7. Then raise the temperature to 1000-1100°C, control the pressure of the reaction chamber at 200-600mbar, and continue to grow a 60-90nm magnesium-doped P-type GaN layer;

8. Finally, lower the temperature to 650-700°C, keep it warm for 20-30 minutes, and then cool in the furnace to obtain sample 1. the

Embodiment one,

The invention uses AixtronCruisIIMOCVD to grow high-brightness GaN-based LED epitaxial wafers. Use high-purity _H2 or high-purity _N2 or the mixed gas of high-purity _H2 and high-purity _N2 as carrier gas, high-purity NH3 as N source, trimethylgallium (TMGa) and triethylgallium (TEGa) as Gallium source, trimethylindium (TMIn) as indium source, silane (SiH ₄ ) as N-type dopant, trimethylaluminum (TMAl) as aluminum source, and dichloromagnesium (CP ₂ Mg) as P-type dopant agent, the substrate is (0001) sapphire, and the reaction chamber pressure is between 150mbar and 600mbar.

1. Under the hydrogen atmosphere of 1000-1100℃, the pressure of the reaction chamber is controlled at 150-200mbar, and the sapphire substrate is treated at high temperature for 4-5 minutes;

2. Lower the temperature to 540-570°C, control the pressure of the reaction chamber at 450-600mbar, and grow a low-temperature buffer layer GaN with a thickness of 30-50nm on the sapphire substrate;

3. Raise the temperature to 950-1050°C, control the pressure of the reaction chamber at 450-600mbar, and continue to grow 2.5-3.0um undoped GaN;

4. Keep the temperature constant, control the pressure of the reaction chamber at 200-400mbar, and then grow 3.5-4.5μm N-type GaN continuously doped with silicon;

5. Lower the temperature to 710-840°C, control the pressure of the reaction chamber at 300-400mbar, and grow the multi-quantum well light-emitting layer periodically. The single-cycle growth method:

(1) Cool down to 710-750°C, grow In _x Ga _(1-x) N well layer of 2.7-3.5nm doped with In, x=0.20-0.22;

(2) Keep the temperature and pressure constant, and grow In _z Ga _(1-z) N well layer of 0.5-1.0 nm doped with In by changing the flow rate of indium, z=0.04-0.08;

(3) Keeping the pressure constant, raise the temperature to 810-840°C to grow 4-6nm Al _x1 In _x2 Ga _(1-x1-x2) N epitaxy layer doped with aluminum and indium, x ₁ =0.04-0.05, x ₂ =0.10-0.12;

(4) Keep the pressure constant and lower the temperature to 710-750°C to grow an In _x Ga _(1-x) N well layer of 2.7-3.5nm doped with In, x=0.20-0.22;

(5) Keep the temperature and pressure constant, and grow In _z Ga _(1-z) N (z=0.04-0.08) well layer of 0.5-1.0 nm doped with In by changing the flow rate of indium;

(6) Keep the pressure constant and raise the temperature to 810-840°C to grow a 10-12nm GaN epitaxial layer;

Then repeat growth with (1) (2) (3) (4) (5) (6) as a cycle, the number of repeated growth cycles is 6-8, and the overall thickness is controlled at 162-216nm;

6. Then raise the temperature to 900-950°C, control the pressure of the reaction chamber at 150-300mbar, and continue to grow a 30-40nm P-type In _y Al _(1-y) GaN layer doped with indium and aluminum, y=0.08-0.12;

7. Then raise the temperature to 1000-1100°C, control the pressure of the reaction chamber at 200-600mbar, and continue to grow a 60-90nm magnesium-doped P-type GaN layer;

8. Finally, lower the temperature to 650-700°C, keep the temperature for 20-30 minutes, and then cool in the furnace to obtain sample 2. the

The growth parameters of Comparative Example 1 and Example 1 can be seen in Table 1 below. the

The growth parameter contrast of table 1 comparative embodiment one and embodiment one

Note: - in Table 1 means none

Referring to FIG. 1 , the multi-quantum well layer 3-1 and the multi-quantum epitaxial layer 3-2 in sample 1 prepared by the traditional method. Referring to Fig. 2, in the sample 2 prepared by the method of the present invention, the first well layer 3-A, the second well layer 3-B, the first epitaxial layer 3-C, the first well layer 3-A, the second well layer A composite multi-quantum well layer formed by overlapping the second well layer 3-B and the second epitaxial layer 3-D. Referring to Figure 3 and Figure 4, the difference in the structure of the two makes the sample generate corresponding multiple well energy levels, increasing the concentration of holes and electrons, mainly reducing the escape of electrons, increasing the concentration of holes, and improving the recombination efficiency; and, Multiple trap energy levels make the wave functions of electrons and holes closer to their center points in K space, increasing the recombination probability of electrons and holes. the

It can be seen from Figure 3 that the multi-quantum well layer 3-1 and the multi-quantum epitaxial layer 3-2 of sample 1 correspond to the conduction band energy level positions indicated by points A and B respectively in figure (a). (b) corresponds to the positions of the valence band energy levels indicated by points A' and B', respectively. the

It can be seen from Figure 4 that the first well layer 3-A, the second well layer 3-B, the first epitaxial layer 3-C, and the first well layer 3-A of sample 2 respectively correspond to The conduction band energy levels indicated by points A, B, C, and D correspond to the valence band energy levels indicated by points A', B', C', and D' in Figure (b). Location. the

Then, the prepared sample 1 and sample 2 were plated with an ITO layer of 150-200nm under the same pre-process conditions, a Cr/Pt/Au electrode of 130-150nm was plated under the same conditions, and a protective layer of SiO ₂ was plated under the same conditions 40 -50nm, and then grind and cut the sample into chip particles of 305μm*711μm (12mi*28mil) under the same conditions, and then select 150 grains at the same position for sample 1 and sample 2, and package them under the same packaging process. into a white LED. Then an integrating sphere was used to test the photoelectric performance of samples 1 and 2 under the condition of a driving current of 350 mA, and the obtained parameters are shown in FIG. 5 .

The ordinate in Fig. 5 is the light efficiency (1m/w), and the abscissa is the distribution number of chip particles. The value corresponding to sample 2 is the upper thicker line, and the value corresponding to sample 1 is the lower thinner line. From the data in Figure 5, it can be concluded that the light efficiency of sample 2 is 6-7% higher than that of sample 1. The growth method provided by this patent improves the light efficiency of large-size chips. the

Comparative example two,

For the implementation steps, refer to Comparative Example 1 to obtain Sample 3. the

Embodiment two,

For the implementation steps, refer to Example 1 to obtain sample 4. the

The comparison of growth parameters between Comparative Example 2 and Example 2 can be seen in Table 2 below. the

Table 2 contrasts the growth parameters of embodiment two and embodiment two

Then, sample 3 and sample 4 were treated in the same way as sample 1 and sample 2 to test the photoelectric properties of sample 3 and sample 4, and the obtained parameters are shown in FIG. 6 . The ordinate in Fig. 6 is brightness (Lm), and the abscissa is the distribution number of chip particles. The value corresponding to sample 4 is the upper thicker line, and the value corresponding to sample 3 is the lower thinner line. From the data in Figure 6, it can be concluded that the brightness of sample 4 is 8-9% higher than that of sample 3. The growth method provided by this patent improves the light efficiency of large-sized chips. the

Referring to Fig. 2, the present invention also discloses an LED epitaxial structure prepared according to the growth method of the above-mentioned compound multi-quantum well light-emitting layer structure, the well light-emitting layer of the LED epitaxial structure includes 6-8 unit layers, each unit Layers from bottom to top include:

The first well layer 3-A, the first well layer 3-A is an In _x Ga _(1-x) N well layer doped with 2.7-3.5nmIn, x=0.20-0.22;

The second well layer 3-B, the second well layer 3-B is an In _z Ga _(1-z) N well layer doped with 0.5-1.0nmInIn, z=0.04-0.08;

The first epitaxial layer 3-C, the first epitaxial layer 3-C is an Al _x1 In _x2 Ga _(1-x1-x2) N epitaxial layer doped with 4-6nm Al and In, x ₁ =0.04-0.05 , x ₂ =0.10-0.12;

The first well layer 3-A, the first well layer 3-A is an In _x Ga _(1-x) N well layer doped with 2.7-3.5nmIn, x=0.20-0.22;

The second well layer 3-B, the second well layer 3-B is an In _z Ga _(1-z) N well layer doped with 0.5-1.0nmInIn, z=0.04-0.08;

The second epitaxial layer 3-D, the second epitaxial layer 3-D is a 10-12nm GaN epitaxial layer. the

In addition, below the above unit layer from bottom to top, it can also include:

Low-temperature buffer GaN layer 7 with a thickness of 30-50nm; this layer is a nucleation layer grown on the substrate, which provides nucleation islands required for crystal growth for undoped GaN growth, and the nucleation islands further grow into crystals;

The undoped GaN layer 8 has a thickness of 2.5-3.0um; the growth of undoped GaN is based on the nucleation layer, and the nucleation island continues to grow and merge into a complete crystal;

The N-type GaN layer 4 has a thickness of 3.5-4.5 μm and is doped with Si, and the doping concentration of Si is controlled to be 8E+18-1E19 atom/cm ³ .

On the unit layer from bottom to top can also include:

P-type AlGaN layer 6, P-type In _y Al _(1-y) GaN layer with a thickness of 30-40nm, y=0.08-0.12;

The P-type GaN layer 1 has a thickness of 60-90nm and is doped with Mg. The doping concentration of Mg is controlled to be 3E+18-4E18atom/cm ³ .

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. the

Claims (6)

1. a growth method of a compound multi-quantum well light-emitting layer structure, is characterized in that, comprises the following steps: A. Control the temperature at 710-750°C, control the pressure of the reaction chamber at 300-400mbar, and feed In at a flow rate of 1500-1700sccm, and grow In _x Ga _(1-x) N wells of 2.7-3.5nm doped with In layer, x=0.20-0.22; B. Keep the temperature and pressure constant, the flow rate of In is 300-450sccm, grow In _z Ga _(1-z) N well layer of 0.5-1.0nm doped with In, z=0.04-0.08, C. Keep the pressure constant, raise the temperature to 810-840°C, feed Al at a flow rate of 30-50 sccm, and feed In at a flow rate of 800-1000 sccm, and grow 4-6nm Al and In-doped Al _x1 In _x2 Ga _(1-x1-x2) N epitaxy layer, x ₁ =0.04-0.05, x ₂ =0.10-0.12; D. Repeat steps A and B; E. Keep the pressure constant, and raise the temperature to 810-840°C to grow a 10-12nm GaN epitaxial layer; F. Repeat steps A, B, C, D, and E 6-8 times until the overall thickness of the light-emitting layer of the well reaches 162-216 nm. 2. the growth method of a kind of compound multi-quantum well light-emitting layer structure according to claim 1, is characterized in that, comprises step before described step A: S1. Under a hydrogen atmosphere at 1000-1100°C, the reaction chamber pressure is 150-200mbar, and the sapphire substrate is processed for 4-5 minutes; S2. Lower the temperature to 540-570°C, control the pressure of the reaction chamber at 450-600mbar, and grow a low-temperature buffer layer GaN with a thickness of 30-50nm on the sapphire substrate; S3. Raise the temperature to 950-1050°C, control the pressure of the reaction chamber at 450-600mbar, and continue to grow 2.5-3.0um undoped GaN; S4. Keep the temperature constant, control the pressure of the reaction chamber at 200-400mbar, then continue to grow 3.5-4.5μm Si-doped N-type GaN, and control the Si doping concentration at 8E+18-1E19atom/cm ³ . 3. the growth method of a kind of compound multiple quantum well light-emitting layer structure according to claim 1, is characterized in that, comprises steps after described step F: D1. Raise the temperature to 900-950°C, control the pressure of the reaction chamber at 150-300mbar, and continue to grow a 30-40nm P-type In _y Al _(1-y) GaN layer doped with Al and In, y=0.08-0.12; D2. Raise the temperature to 1000-1100°C, control the pressure of the reaction chamber at 200-600mbar, and continue to grow a 60-90nm Mg-doped P-type GaN layer, and control the Mg doping concentration at 3E+18-4E18atom/cm ³ ; D3. Cool down to 650-700°C, keep warm for 20-30 minutes, and cool in the furnace. 4. An LED epitaxial structure, characterized in that, the well light-emitting layer of the LED epitaxial structure includes 6-8 unit layers, and each unit layer sequentially includes from bottom to top: The first well layer, the first well layer is an In _x Ga _(1-x) N well layer doped with 2.7-3.5nmIn, x=0.20-0.22; a second well layer, the second well layer is an In _z Ga _(1-z) N well layer doped with 0.5-1.0nmIn, z=0.04-0.08; The first epitaxial layer, the first epitaxial layer is Al _x1 In _x2 Ga _(1-x1-x2) N epitaxial layer doped with 4-6nm Al and In, x ₁ =0.04-0.05, x ₂ =0.10- 0.12; The first well layer, the first well layer is an In _x Ga _(1-x) N well layer doped with 2.7-3.5nmIn, x=0.20-0.22; a second well layer, the second well layer is an In _z Ga _(1-z) N well layer doped with 0.5-1.0nmIn, z=0.04-0.08; The second epitaxial layer, the second epitaxial layer is a 10-12nm GaN epitaxial layer. 5. The LED epitaxial structure according to claim 4, characterized in that, the unit layers below sequentially include: A low-temperature buffer GaN layer with a thickness of 30-50nm; Undoped GaN layer with a thickness of 2.5-3.0um; The N-type GaN layer has a thickness of 3.5-4.5 μm and is doped with Si, and the doping concentration of Si is controlled to be 8E+18-1E19atom/cm ³ . 6. The LED epitaxial structure according to claim 4, characterized in that, the unit layer comprises from bottom to top: P-type AlGaN layer, P-type In _y Al _(1-y) GaN layer with a thickness of 30-40nm, y=0.08-0.12; The P-type GaN layer has a thickness of 60-90nm and is doped with Mg, and the doping concentration of Mg is controlled to be 3E+18-4E18atom/cm ³ .

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