A method for growing GaN-based epitaxial layers for reducing operating voltage of LED chips

Abstract

The application relates to the technical field of LED chips, in particular to a GaN-based epitaxial layer growth method for reducing the working voltage of an LED chip; S2: setting the reaction cavity temperature to 1000-1100 degrees, the pressure to 250-350 mbar, and inputting ammonia, hydrogen, 300-400 sccm of TMGa2 and 100-200 sccm of dimethyl magnesium; continuously for 6-9 minutes; forming a doped U-shaped GaN layer on a buffer layer; S3: setting the reaction cavity pressure to 250-350 mbar, the temperature to 1100-1300 degrees, and inputting nitrogen, hydrogen, ammonia and TMGa2; continuously for 4-5 minutes, forming an undoped U-shaped GaN layer on the doped U-shaped GaN layer; the GaN-based epitaxial layer reduces the working voltage by about 0.2-0.28 V compared with the epitaxial layer of a conventional LED chip; the antistatic capacity is increased by 20%-30% compared with a conventional LED structure, and the brightness is increased by 5%-15% compared with a conventional LED structure.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LED chip, and particularly relates to a GaN-based epitaxial layer growth method for reducing the working voltage of an LED chip. BACKGROUND

[0002] As a high-efficiency, environmentally-friendly, green new type of solid-state lighting source, GaN-based light-emitting diodes (LEDs) have low voltage, low power consumption, small size, light weight, long service life, high reliability and other advantages, and are rapidly being widely applied to traffic signal lights, mobile phone backlights, outdoor full-color display screens, urban landscape lighting, car interior and exterior lights, tunnel lights and other fields. Therefore, the performance improvement of the LED in all aspects is focused by the industry.

[0003] In the preparation of GaN-based LED epitaxial layers, the characteristics of the roughening layer (U-shaped GaN layer) are an important factor affecting the electrical properties of the LED. At present, the growth of the roughening layer is involved in the growth of the LED epitaxial layer by MOCVD, and a roughening layer is directly grown after the buffer layer is grown without any doping. Although this method is beneficial to the lattice matching with the next N-type GaN layer, it will lead to high working voltage of the LED chip, increased energy consumption of the device, and low light-emitting efficiency.

[0004] In order to solve the above problems, the Chinese patent with publication number CN104009136A discloses an LED epitaxial layer growth method for improving light-emitting efficiency, which is composed of a low-temperature grown P-type AlGaN / GaN superlattice layer and a high-temperature grown P-type AlGaN / GaN superlattice layer, effectively reducing the Droop effect of the LED chip under a large current density, improving the injection efficiency of the carriers, and improving the light-emitting efficiency of the device.

[0005] However, the above scheme can significantly improve the light-emitting efficiency of the LED chip, but the effect of reducing the working voltage and the driving voltage is still not good. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a GaN-based epitaxial layer growth method for reducing the working voltage of an LED chip, effectively reducing the working voltage of the LED chip, improving the anti-static capability of the LED chip, and improving the light-emitting efficiency of the LED chip.

[0007] In order to solve the above technical problem, a technical solution adopted by the present application is as follows: a GaN-based epitaxial layer growth method for reducing the working voltage of an LED chip, comprising the following steps:

[0008] S1: placing an AlN substrate into a reaction cavity of a metal organic chemical vapor deposition device; and growing a buffer layer on the substrate;

[0009] S2: set the reaction cavity temperature to 1000-1100 degrees, the pressure to 250-350 mbar, and introduce ammonia, hydrogen, 300-400 sccm of TMGa2 and 100-200 sccm of dimethyl magnesium; last for 6-9 minutes; form a doped U-shaped GaN layer on the buffer layer;

[0010] S3: set the reaction cavity pressure to 250-350 mbar and the temperature to 1100-1300 degrees, and introduce nitrogen, hydrogen, ammonia and TMGa2; last for 4-5 minutes, so as to form an undoped U-shaped GaN layer on the doped U-shaped GaN layer;

[0011] S4: grow a 2-3 micron N-type GaN layer on the undoped U-shaped GaN layer;

[0012] S5: grow a quantum well layer on the N-type GaN layer;

[0013] S6: grow a P-type GaN layer on the quantum well layer;

[0014] S7: complete the growth of the GaN-based epitaxial layer.

[0015] The GaN-based epitaxial layer growth method for reducing the working voltage of the LED chip provided by the application has the advantages that: the U-shaped GaN layer of the LED chip is generated in two steps and is composed of two structures by the S2 and S3. The U-shaped GaN layer of the GaN-based epitaxial layer comprises a doped U-shaped GaN layer (the doping element is Mg) with low temperature and high doping concentration and an undoped U-shaped GaN layer with high temperature doping, which improves the hole mobility in the U-shaped GaN layer and improves the quality and anti-static capacity of the LED chip; the GaN-based epitaxial layer reduces the working voltage by about 0.2-0.28 V compared with the conventional epitaxial layer of the LED chip; the anti-static capacity is increased by 20%-30% compared with the conventional LED structure, and the brightness is increased by 5%-15% compared with the conventional LED structure. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a whole structure schematic view of the GaN-based epitaxial layer of the embodiment of the application;

[0017] Figure 2 It is an I-V curve diagram of the comparative example of the embodiment of the application;

[0018] Label explanation:

[0019] 1, AlN substrate; 2, buffer layer; 3, doped U-shaped GaN layer; 4, undoped U-shaped GaN layer;

[0020] 5. N-type GaN layer; 6. Multi-quantum well active region layer; 7. Low-temperature P-type GaN layer; 8. Superlattice layer; 9. High-temperature P-type GaN layer. DETAILED DESCRIPTION

[0021] To make the technical contents of the present application, the purposes and effects achieved more clear, the following will be described in detail in combination with the embodiments and the accompanying drawings.

[0022] A GaN-based epitaxial layer growth method for reducing the working voltage of LED chip, comprising the following steps:

[0023] S1: Put the AlN substrate 1 into the reaction cavity of the metal organic chemical vapor deposition device; and grow a buffer layer 2 on the substrate;

[0024] S2: Set the temperature of the reaction cavity to 1000-1100 degrees, the pressure to 250-350 mbar, and input ammonia, hydrogen, 300-400 sccm of TMGa2 and 100-200 sccm of dimethyl magnesium; continue for 6-9 minutes; and form a doped U-shaped GaN layer 3 on the buffer layer;

[0025] S3: Set the pressure of the reaction cavity to 250-350 mbar, the temperature to 1100-1300 degrees, and input nitrogen, hydrogen, ammonia and TMGa2; continue for 4-5 minutes, so as to form an undoped U-shaped GaN layer 4 on the doped U-shaped GaN layer;

[0026] S4: Grow a 2-3 micrometer N-type GaN layer 5 on the undoped U-shaped GaN layer;

[0027] S5: Grow a quantum well layer on the N-type GaN layer;

[0028] S6: Grow a P-type GaN layer on the quantum well layer;

[0029] S7: Complete the growth of the GaN-based epitaxial layer.

[0030] From the above description, the beneficial effects of the present application are that: the GaN-based epitaxial layer growth method for reducing the working voltage of the LED chip provided by the present application, the S2 and S3 divide the U-shaped GaN layer of the LED chip into two steps, and are composed of two structures. The U-shaped GaN layer of the GaN-based epitaxial layer includes a low-temperature high-doping-concentration doped U-shaped GaN layer (doping element is Mg) and a high-temperature doped undoped U-shaped GaN layer. This structure improves the hole mobility in the U-shaped GaN layer and improves the quality and anti-static capability of the LED chip. The working voltage of the GaN-based epitaxial layer is reduced by about 0.2-0.28V compared with the conventional epitaxial layer of the LED chip. The anti-static capability is increased by 20%-30% compared with the conventional LED structure, and the brightness is increased by 5%-15% compared with the conventional LED structure.

[0031] Further, the "growing a buffer layer on the substrate" of S1 is specifically:

[0032] The reaction cavity pressure is set to 100-200mbar, the temperature is 800-900 degrees, hydrogen, ammonia, 60-80sccm of TMGa2 and 25-45sccm of TMAl are introduced, and the process lasts for 4-6 minutes; a 0.1-0.2 micron buffer layer is grown on the substrate.

[0033] From the above description, the above setting provides a simple and efficient method for generating a buffer layer, and the process of generating a buffer layer is high-quality and efficient.

[0034] Further, S4 is specifically: setting the reaction cavity temperature to 1000-1100 degrees and the pressure to 500-1000mbar, growing a 2-3 micron N-type GaN layer on the undoped U-shaped GaN layer.

[0035] From the above description, the above setting provides a temperature and pressure for generating an N-type GaN layer, and an electrode is provided on the N-type GaN layer.

[0036] Further, S5 is specifically: while introducing ammonia, hydrogen, nitrogen and TMGa2 into the reaction cavity, intermittently introducing TMIn, so as to grow a periodic InGaN / GaN multi-quantum well active region layer on the N-type GaN layer.

[0037] From the above description, the In element is doped into the quantum well layer, which helps to reduce the working voltage of the LED chip.

[0038] Further, the S5 is specifically setting the reaction cavity pressure to 500-1000 mbar and temperature to 700-800 degrees, while continuously feeding ammonia, hydrogen, nitrogen and 25-40 sccm of TMGa2, and intermittently feeding 1200-1500 sccm of TMIn, so as to grow a periodic InGaN / GaN multi-quantum well active region layer on the N-type GaN layer, the period number of InGaN / GaN being 10-16; the multi-quantum well active region layer 6 has a thickness of 0.15-0.2 microns, and the In doping concentration is 1E+20-2E+20 atom / cm 3 .

[0039] It can be known from the above description that the method for generating a multi-quantum well active region layer is simple and efficient.

[0040] Further, the S6 specifically includes S6.1, S6.2 and S6.3.

[0041] S6.1: growing a low-temperature P-type GaN layer 7 on the quantum well layer;

[0042] S6.2: feeding NH3, TMGa2, Cp2Mg and TMAl into the reaction cavity, so as to grow a periodic AlGaN / GaN superlattice layer 8 on the low-temperature P-type GaN layer;

[0043] S6.3: forming a doped high-temperature P-type GaN layer 9 on the superlattice layer.

[0044] It can be known from the above description that the above steps are beneficial to reduce the Droop effect of the LED chip under a large current density, improve the carrier injection efficiency, and improve the light-emitting efficiency of the device.

[0045] Further, the S6.1 is specifically setting the reaction cavity temperature to 600-700 degrees and the pressure to 300-800 mbar, feeding 55000-65000 sccm of NH3 and 25-50 sccm of TMGa2, and forming a low-temperature P-type GaN layer with a thickness of 60-90 nm on the quantum well layer.

[0046] It can be known from the above description that the above setting provides a simple and efficient method for generating a low-temperature P-type GaN layer.

[0047] Further, the S6.2 is specifically: setting the temperature of the reaction cavity to 700-950 degrees, the pressure to 300-800 mbar, and introducing 30000-60000 sccm of NH3, 30-50 sccm of TMGa2, 1500-2000 sccm of Cp2Mg and 150-200 sccm of TMAl, so that a periodic AlGaN / GaN superlattice layer is grown on the low-temperature P-type GaN layer; the period of the AlGaN / GaN is 5-10, the single-layer thickness of the AlGaN is 4-6 nm, and the thickness ratio of the AlGaN and GaN layers in a single period is 1:1-3:1; the thickness of the superlattice layer is 50-70 nm, the doping concentration of Mg is 1E+18-1E+19 atom / cm 3 , and the doping concentration of Al is 1E+17-1E+18 atom / cm 3 .

[0048] From the above description, it can be seen that the above setting provides a simple and efficient method for generating a superlattice layer.

[0049] Further, the S6.3 is specifically: setting the temperature of the reaction cavity to 900-1050 degrees, the pressure to 600-1000 mbar, and introducing 60000-75000 sccm of NH3, 25-50 sccm of TMGa2 and 2000-3000 sccm of Cp2Mg, so that a doped high-temperature P-type GaN layer is formed on the superlattice layer; the thickness of the high-temperature P-type GaN layer is 60-90 nm, and the doping concentration of Mg is 1E+20-3E+20 atom / cm 3 .

[0050] From the above description, it can be seen that the above setting provides a simple and efficient method for generating a high-temperature P-type GaN layer.

[0051] Embodiment one

[0052] The embodiment provides a GaN-based epitaxial layer growth method for reducing the working voltage of an LED chip, which comprises the following steps:

[0053] S1: placing an AlN substrate into a reaction cavity of a metal organic chemical vapor deposition device; setting the pressure of the reaction cavity to 100-200 mbar, the temperature to 800-900 degrees, and introducing hydrogen, ammonia, 60-80 sccm of TMGa2 and 25-45 sccm of TMAl for 4-6 minutes; so that a 0.1-0.2 micron buffer layer is grown on the substrate;

[0054] S2: set the temperature of the reaction cavity 1000-1100 degrees, pressure 250-350 mbar, into the ammonia, hydrogen, 300-400 sccm of TMGa2 and 100-200 sccm of dimethyl magnesium; last 6-9 minutes; make the buffer layer on the formation of doped U-shaped GaN layer;

[0055] S3: set the reaction cavity pressure 250-350 mbar, temperature 1100-1300 degrees, into the nitrogen, hydrogen, ammonia and TMGa2; last 4-5 minutes, make the doped U-shaped GaN layer on the formation of undoped U-shaped GaN layer;

[0056] S4: set the temperature of the reaction cavity 1000-1100 degrees, pressure 500-1000 mbar, on the undoped U-shaped GaN layer growth of 2-3 microns of N type GaN layer;

[0057] S5: set the reaction cavity pressure 500-1000 mbar, temperature 700-800 degrees, while into the ammonia, hydrogen, nitrogen and 25-40 sccm of TMGa2, intermittent into 1200-1500 sccm of TMIn, make the N type GaN layer growth of periodic InGaN / GaN multi quantum well active region layer, InGaN / GaN cycle number is 10-16; the multi quantum well active region layer thickness is 0.15-0.2 microns, In doping concentration is 1E+20-2E+20 atom / cm 3 ;

[0058] S6: set the temperature of the reaction cavity 600-700 degrees, pressure 300-800 mbar, into 55000-65000 sccm of NH3 and 25-50 sccm of TMGa2, on the multi quantum well active region layer formation thickness 60-90 nm of low temperature P type GaN layer;

[0059] S7: set the temperature of the reaction cavity 700-950 degrees, pressure 300-800 mbar, into 30000-60000 sccm of NH3, 30-50 sccm of TMGa2, 1500-2000 sccm of Cp2Mg and 150-200 sccm of TMAl, make the low temperature P type GaN layer growth of periodic AlGaN / GaN superlattice layer; AlGaN / GaN cycle is 5-10, AlGaN monolayer thickness is 4-6 nm, the thickness ratio of AlGaN and GaN layer in a single cycle is 1:1-3:1; the superlattice layer thickness is 50-70 nm, Mg doping concentration is 1E+18-1E+19 atom / cm 3 , Al doping concentration is 1E+17-1E+18 atom / cm 3 ;

[0060] S8: set the temperature of the reaction chamber to 900-1050 degrees, the pressure to 600-1000 mbar, and introduce 60000-75000 sccm of NH3, 25-50 sccm of TMGa2, and 2000-3000 sccm of Cp2Mg, to form a doped high-temperature P-type GaN layer on the superlattice layer; the high-temperature P-type GaN layer has a thickness of 60-90 nm, and the doping concentration of Mg is 1E+20-3E+20 atom / cm 3 ;

[0061] S9: complete the growth of the GaN-based epitaxial layer.

[0062] Example Two

[0063] The present example provides a GaN-based epitaxial layer growth method for reducing the operating voltage of an LED chip, comprising the following steps:

[0064] S1: place an AlN substrate into the reaction chamber of a metal organic chemical vapor deposition device; set the pressure of the reaction chamber to 100 mbar and the temperature to 800 degrees, and introduce hydrogen, ammonia, 60 sccm of TMGa2, and 25 sccm of TMAl, for 4 minutes; grow a 0.1 micron buffer layer on the substrate;

[0065] S2: set the temperature of the reaction chamber to 1000 degrees and the pressure to 250 mbar, and introduce ammonia, hydrogen, 300 sccm of TMGa2, and 100 sccm of dimethyl magnesium; continue for 6 minutes; form a doped U-type GaN layer on the buffer layer;

[0066] S3: set the pressure of the reaction chamber to 250 mbar and the temperature to 1100 degrees, and introduce nitrogen, hydrogen, ammonia, and TMGa2; continue for 4 minutes, to form an undoped U-type GaN layer on the doped U-type GaN layer;

[0067] S4: set the temperature of the reaction chamber to 1000 degrees and the pressure to 500 mbar, and grow a 2 micron N-type GaN layer on the undoped U-type GaN layer;

[0068] S5: set the pressure of the reaction chamber to 500 mbar and the temperature to 700 degrees, and introduce ammonia, hydrogen, nitrogen, and 25 sccm of TMGa2, while intermittently introducing 1200 sccm of TMIn, to grow a periodic InGaN / GaN multi-quantum well active region layer on the N-type GaN layer; the period of InGaN / GaN is 10; the doping concentration of In is 1E+20 atom / cm 3 ;

[0069] S6: set the reaction cavity temperature to 600 degrees, the pressure to 300-800 mbar, introduce 55000 sccm of NH3 and 25 sccm of TMGa2, and form a low-temperature P-type GaN layer with a thickness of 60 nm on the multi-quantum well active region layer;

[0070] S7: set the reaction cavity temperature to 700 degrees, the pressure to 300 mbar, introduce 30000 sccm of NH3, 30 sccm of TMGa2, 1500 sccm of Cp2Mg and 150 sccm of TMAl, and grow a periodic AlGaN / GaN superlattice layer on the low-temperature P-type GaN layer; the period of AlGaN / GaN is 5, the single-layer thickness of AlGaN is 4 nm, and the thickness ratio of AlGaN and GaN layers in a single period is 1:1-3:1; the doping concentration of Mg is 1E+18 atom / cm 3 , and the doping concentration of Al is 1E+17 atom / cm 3 ;

[0071] S8: set the reaction cavity temperature to 900 degrees, the pressure to 600 mbar, introduce 60000 sccm of NH3, 25 sccm of TMGa2 and 2000 sccm of Cp2Mg, and form a doped high-temperature P-type GaN layer on the superlattice layer; the doping concentration of Mg is 1E+20 atom / cm 3 ;

[0072] S9: complete the growth of the GaN-based epitaxial layer.

[0073] Example Three

[0074] The embodiment provides a GaN-based epitaxial layer growth method for reducing the working voltage of an LED chip, comprising the following steps:

[0075] S1: place an AlN substrate into a reaction cavity of a metal organic chemical vapor deposition device; set the reaction cavity pressure to 150 mbar and the temperature to 850 degrees, introduce hydrogen, ammonia, 70 sccm of TMGa2 and 30 sccm of TMAl, and maintain for 5 minutes; and grow a 0.15-micron buffer layer on the substrate;

[0076] S2: set the reaction cavity temperature to 1050 degrees and the pressure to 300 mbar, introduce ammonia, hydrogen, 350 sccm of TMGa2 and 150 sccm of dimethyl magnesium; maintain for 7.5 minutes; and form a doped U-type GaN layer on the buffer layer;

[0077] S3: set the reaction cavity pressure to 300 mbar and the temperature to 1200 degrees, introduce nitrogen, hydrogen, ammonia and TMGa2; maintain for 4.5 minutes, and form an undoped U-type GaN layer on the doped U-type GaN layer.

[0078] S4: Set the temperature of the reaction chamber to 1050 degrees, and the pressure to 750 mbar. Grow a 2.5 micron N-type GaN layer on the undoped U-shaped GaN layer.

[0079] S5: Set the pressure of the reaction chamber to 750 mbar, and the temperature to 750 degrees. Intermittently introduce 1350 sccm of TMIn while introducing ammonia, hydrogen, nitrogen, and 33 sccm of TMGa2, so as to grow a periodic InGaN / GaN multi-quantum well active region layer on the N-type GaN layer. The period of InGaN / GaN is 13. The doping concentration of In is 1.5E+20 atom / cm 3 ;

[0080] S6: Set the temperature of the reaction chamber to 600-700 degrees, and the pressure to 300-800 mbar. Introduce 55000-65000 sccm of NH3 and 25-50 sccm of TMGa2, so as to form a low-temperature P-type GaN layer with a thickness of 60-90 nm on the multi-quantum well active region layer.

[0081] S7: Set the temperature of the reaction chamber to 825 degrees, and the pressure to 550 mbar. Introduce 45000 sccm of NH3, 30-50 sccm of TMGa2, 1500-2000 sccm of Cp2Mg, and 150-200 sccm of TMAl, so as to grow a periodic AlGaN / GaN superlattice layer on the low-temperature P-type GaN layer. The period of AlGaN / GaN is 5-10, the single-layer thickness of AlGaN is 4-6 nm, the thickness of the superlattice layer is 50-70 nm, the doping concentration of Mg is 1E+18-1E+19 atom / cm 3 , and the doping concentration of Al is 1E+17-1E+18 atom / cm 3 ;

[0082] S8: Set the temperature of the reaction chamber to 975 degrees, and the pressure to 800 mbar. Introduce 60000-75000 sccm of NH3, 25-50 sccm of TMGa2, and 2000-3000 sccm of Cp2Mg, so as to form a doped high-temperature P-type GaN layer on the superlattice layer. The thickness of the high-temperature P-type GaN layer is 60-90 nm, and the doping concentration of Mg is 1E+20-3E+20 atom / cm 3 ;

[0083] S9: Complete the growth of the GaN-based epitaxial layer.

[0084] Comparative Example

[0085] Table 1

[0086]

[0087] In Table 1, Sample 1 is an LED chip produced using the GaN-based epitaxial layer growth method for reducing the operating voltage of LED chips provided by this invention, and Sample 2 is a conventional LED chip.

[0088] Appendix Figure 2 The curve with a steeper slope is the IV curve of the GaN-based epitaxial structure of this invention, while the curve with a gentler slope is the IV curve of the conventional GaN-based epitaxial structure.

[0089] Observation Table 1 and Appendix Figure 2 It is easy to see that the LED chip produced by using the GaN-based epitaxial layer growth method for reducing the operating voltage of LED chips provided by the present invention has a significantly lower operating voltage and a 15% higher luminous flux.

[0090] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification and drawings, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A GaN-based epitaxial layer growth method for reducing the operating voltage of an LED chip, characterized by, The method comprises the following steps: S1: placing an AlN substrate into a reaction chamber of a metal organic chemical vapor deposition device; growing a buffer layer on the substrate; S2: setting the temperature of the reaction chamber to 1000-1100 degrees, the pressure to 250-350 mbar, and introducing ammonia, hydrogen, 300-400 sccm of TMGa2 and 100-200 sccm of dimethyl magnesium; continuing for 6-9 minutes; forming a doped U-shaped GaN layer on the buffer layer; S3: setting the pressure of the reaction chamber to 250-350 mbar and the temperature to 1100-1300 degrees, and introducing nitrogen, hydrogen, ammonia and TMGa2; continuing for 4-5 minutes, so as to form an undoped U-shaped GaN layer on the doped U-shaped GaN layer; S4: growing a 2-3 micron N-type GaN layer on the undoped U-shaped GaN layer; S5: growing a quantum well layer on the N-type GaN layer; S6: growing a P-type GaN layer on the quantum well layer; S7: completing the growth of the GaN-based epitaxial layer.

2. The GaN-based epitaxial layer growth method for reducing the operating voltage of an LED chip according to claim 1, wherein The "growing a buffer layer on the substrate" in S1 is specifically: setting the pressure of the reaction chamber to 100-200 mbar and the temperature to 800-900 degrees, and introducing hydrogen, ammonia, 60-80 sccm of TMGa2 and 25-45 sccm of TMAl, and continuing for 4-6 minutes; growing a 0.1-0.2 micron buffer layer on the substrate.

3. The method for growing a GaN-based epitaxial layer to reduce the operating voltage of an LED chip according to claim 1, characterized in that, S4 is specifically: setting the temperature of the reaction chamber to 1000-1100 degrees and the pressure to 500-1000 mbar, and growing a 2-3 micron N-type GaN layer on the undoped U-shaped GaN layer.

4. The method of claim 1, wherein the method is a GaN-based epitaxial layer growth method for reducing an operating voltage of an LED chip, the method comprising: S5 is specifically: while introducing ammonia, hydrogen, nitrogen and TMGa2 into the reaction chamber, intermittently introducing TMIn, so as to grow a periodic InGaN / GaN multi-quantum well active region layer on the N-type GaN layer.

5. The GaN-based epitaxial layer growth method for reducing the operating voltage of an LED chip according to claim 4, wherein The S5 is specifically setting the reaction cavity pressure to 500-1000 mbar and temperature to 700-800 degrees, while intermittently passing in 1200-1500 sccm of TMIn, and simultaneously passing in ammonia, hydrogen, nitrogen and 25-40 sccm of TMGa2, so that a periodic InGaN / GaN multi-quantum well active region layer is grown on the N-type GaN layer, the period number of InGaN / GaN is 10-16; the thickness of the multi-quantum well active region layer is 0.15-0.2 microns, and the doping concentration of In is 1E+20-2E+20 atom / cm 3 .

6. The method for growing a GaN-based epitaxial layer to reduce the operating voltage of an LED chip according to claim 1, characterized in that, S6 specifically comprises S6.1, S6.2 and S6.3; S6.1: growing a low-temperature P-type GaN layer on the quantum well layer; S6.2: introducing NH3, TMGa2, Cp2Mg and TMAl into the reaction chamber, so as to grow a periodic AlGaN / GaN superlattice layer on the low-temperature P-type GaN layer; S6.3: forming a doped high-temperature P-type GaN layer on the superlattice layer.

7. The method of claim 6, wherein the method further comprises: growing a GaN-based buffer layer on the substrate; and growing a GaN-based nucleation layer on the buffer layer. S6.1 is specifically: setting the temperature of the reaction chamber to 600-700 degrees and the pressure to 300-800 mbar, and introducing 55000-65000 sccm of NH3 and 25-50 sccm of TMGa2, so as to form a 60-90 nm thick low-temperature P-type GaN layer on the quantum well layer.

8. The method of claim 6, wherein the method further comprises: The S6.2 is specifically: setting the temperature of the reaction cavity to 700-950 degrees, the pressure to 300-800 mbar, and introducing 30000-60000 sccm of NH3, 30-50 sccm of TMGa2, 1500-2000 sccm of Cp2Mg and 150-200 sccm of TMAl, so that a periodic AlGaN / GaN superlattice layer is grown on the low-temperature P-type GaN layer; the period of the AlGaN / GaN is 5-10, the single-layer thickness of the AlGaN is 4-6 nm, and the thickness ratio of the AlGaN and GaN layers in a single period is 1:1-3:1; the thickness of the superlattice layer is 50-70 nm, the doping concentration of Mg is 1E+18-1E+19 atom / cm 3 , and the doping concentration of Al is 1E+17-1E+18 atom / cm 3 .

9. The method of claim 6, wherein the method further comprises: growing a GaN-based buffer layer on the substrate; and growing a GaN-based nucleation layer on the buffer layer. The S6.3 is specifically: setting the temperature of the reaction cavity to 900-1050 degrees, the pressure to 600-1000 mbar, and introducing 60000-75000 sccm of NH3, 25-50 sccm of TMGa2 and 2000-3000 sccm of Cp2Mg, to form a doped high-temperature P-type GaN layer on the superlattice layer; the high-temperature P-type GaN layer has a thickness of 60-90 nm, and the doping concentration of Mg is 1E+20-3E+20 atom / cm 3 .

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