Epitaxial structure for improving GaN-based lighting effect and growth method thereof

Abstract

The invention relates to the technical field of GaN-based light emitting diodes, in particular to an epitaxial structure for improving the GaN-based lighting effect and a growth method of the epitaxial structure. The growth method comprises the step of growing a multi-quantum well active region layer, and the step of growing the multi-quantum well active region layer comprises the following substeps that a defect induction layer, a current expansion layer and a multi-quantum well light-emitting layer are sequentially grown, InGaN quantum well layers and GaN quantum barrier layers in the multi-quantum well light-emitting layer are alternately stacked, and the growth temperature and the In content change in a sinusoidal mode. According to the growth method, a multi-quantum well is produced by adopting a similar sine temperature growth curve, so that the purposes of releasing stress, improving voltage under low current and improving light efficiency are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of GaN-based light-emitting diodes, and in particular to an epitaxial structure and a growth method thereof for improving GaN-based light efficiency. Background Art

[0002] At present, GaN-based light emitting diodes (LEDs) have been widely used in solid-state lighting and display fields due to their high efficiency, energy saving, and environmental protection. As the core area of ​​GaN-based light emitting diodes, multi-quantum well structures have also been widely studied. The multi-quantum well structure is generally composed of InGaN quantum well layers and GaN quantum barrier layers stacked alternately. As shown in the Chinese invention with application number 202310675611.5, the traditional InGaN quantum well layer and GaN quantum barrier layer grow alternately in a rectangular temperature curve. This growth method can improve the lattice quality of the stress release layer, delay the generation of V-type defects, reduce the number of V-type defects, and alleviate the Stark effect, thereby improving the luminous efficiency and the crystal quality of the multi-quantum well layer; however, this growth method has a large energy band change and still fails to meet the market demand for high light efficiency of TV backlight. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an epitaxial structure and a growth method thereof for improving GaN-based light efficiency.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for growing an epitaxial structure for improving the light efficiency of GaN-based structures, comprising the step of growing a multi-quantum well active region layer, wherein the growth of the multi-quantum well active region layer comprises the following steps: sequentially growing a defect inducing layer, a current expansion layer and a multi-quantum well light-emitting layer, wherein InGaN quantum well layers and GaN quantum barrier layers in the multi-quantum well light-emitting layer are alternately stacked and the growth temperature and In content vary sinusoidally.

[0005] Another technical solution adopted by the present invention is: an epitaxial structure is prepared by adopting the above-mentioned growth method of the epitaxial structure for improving the light efficiency of GaN-based epitaxial structure.

[0006] The beneficial effect of the present invention is that the growth method of the present invention adopts a similar sinusoidal temperature growth curve to produce multiple quantum wells, so as to achieve the purpose of releasing stress, increasing voltage under low current and improving light efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a structural schematic diagram of an epitaxial structure in a specific implementation manner of the present invention; Figure 2 It is a curve diagram showing sinusoidal changes in temperature in Examples 1 to 3 of the present invention; Figure 3 It is a curve diagram showing a rectangular change in temperature in Comparative Example 1 of the present invention; Description of labels: 1. Substrate; 2. Buffer layer; 3. U-type GaN layer; 4. N-type GaN layer; 5. Defect induction layer; 6. Current spreading layer; 7. Multi-quantum well light-emitting layer; 8. Low-temperature P-type GaN layer; 9. P-type electron blocking layer; 10. High-temperature P-type GaN layer. DETAILED DESCRIPTION

[0008] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in combination with the implementation modes and the accompanying drawings.

[0009] A method for growing an epitaxial structure for improving GaN-based light efficiency comprises the step of growing a multi-quantum well active region layer, wherein the growing of the multi-quantum well active region layer comprises the following steps: sequentially growing a defect inducing layer, a current spreading layer and a multi-quantum well light-emitting layer, wherein InGaN quantum well layers and GaN quantum barrier layers in the multi-quantum well light-emitting layer are alternately stacked and the growth temperature and In content vary sinusoidally.

[0010] From the above description, it can be seen that due to the large lattice mismatch and thermal mismatch between the gallium nitride material and the sapphire substrate, there is a large stress in the epitaxial growth, which in turn produces a V-shaped defect. The growth method of the present invention uses a sinusoidal temperature growth curve to produce multiple quantum wells. Compared with the conventional rectangular temperature curve, it can release stress more effectively, change the size of the V-shaped defect, improve crystal quality and reduce In aggregation, and increase the voltage under small current, thereby achieving the purpose of improving light efficiency.

[0011] Furthermore, the material of the defect inducing layer is heavily doped N-oxide.

[0012] Furthermore, the material of the current spreading layer is GaN doped with any one of Si, In, Al and Mg doping sources.

[0013] Preferably, the doping source is Si.

[0014] Furthermore, the defect inducing layer is grown in a reaction chamber at a temperature of 700-950°C and 30,000-60,000 sccm of NH 3 .

[0015] From the above description, it can be seen that the present invention provides a simple and efficient defect inducing layer growth method, which can induce the generation of defects, control the size of V-shaped defects and the location of generation, so that the size of V defects in the well epitaxial layer of the multi-quantum active region is basically consistent, which can effectively improve the problem of PN layer interlacing caused by uneven thickness in the crystal stacking process, reduce the thyristor effect, and improve the consistency of chip brightness under different currents.

[0016] Furthermore, the thickness of the defect inducing layer is 2-30 nm.

[0017] Furthermore, when the doping source in the current spreading layer is Al, the growth of the current spreading layer is carried out in a reaction chamber, the temperature of the reaction chamber is 700-950°C, and 30000-60000sccm of NH 3 , 30~50sccm of TMGa and 150~200sccm of TMAl.

[0018] Furthermore, the thickness of the current spreading layer is 10-30 nm.

[0019] Furthermore, the molar number of Al in the current spreading layer decreases linearly in the direction approaching the substrate.

[0020] From the above description, it can be seen that the present invention provides a simple and efficient current spreading layer to replace the traditional low-doped / undoped spreading layer. The traditional spreading layer has weak P-type conductivity due to low Si doping and high C content, and forms three PN contact surfaces with the N-type conductive light-emitting layer and P-layer GaN layer behind it, producing a strong thyristor effect. The current spreading layer of the present invention can effectively improve the current spreading and minimize the thyristor effect to the greatest extent, thereby improving the consistency of chip brightness under different currents.

[0021] Furthermore, the InGaN quantum well layer is grown in a reaction chamber, the temperature of the reaction chamber is 790-850° C., and 1200-3000 sccm of TMIn is introduced.

[0022] Furthermore, when growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 820°C within 1 to 2 minutes, and 1200 sccm of TMIn is introduced at the same time, and Si-doped InGaN grows during the change process; then the temperature is lowered to 810°C within 1 to 2 minutes, and 1800 sccm of In is introduced at the same time, and Si-doped InGaN grows during the cooling process; then the temperature is lowered to 800°C within 0.5 to 1 minute, and 2400 sccm of TMIn is introduced at the same time, and InGaN grows during the cooling process; then The temperature is lowered to 790°C within 0.5~1min, and 2400sccm of TMIn is introduced at the same time, and InGaN grows during the cooling process; then the temperature is raised to 795°C within 0.5~1min, and 2400sccm of TMIn is introduced at the same time, and InGaN grows during the heating process; then the temperature is raised to 800°C within 1~2min, and 2400sccm of TMIn is introduced at the same time, and InGaN grows during the heating process; then the temperature is raised to 825°C within 1~2min, and 1600sccm of TMIn is introduced at the same time.

[0023] From the above description, it can be seen that when the present invention grows the InGaN quantum well layer, the temperature change needs to control the interface between the Si-doped and non-Si-doped InGaN film layers, from the lowest temperature of 790 degrees to the highest temperature of 825 degrees. Because there will be overshoot during the temperature change, the temperature of the two should be controlled in a process window of 0~30°C. At the same time, Si is doped into the first few well layers (at the lowest amplitude) to change the size of V_pits (V-type defects) to achieve the effect of improving the electron injection efficiency.

[0024] The change in temperature requires controlling the interface between the Si-doped and non-Si-doped InGaN film layers, from a minimum temperature of 790 degrees to a maximum temperature of 825 degrees. Because there will be overshoot during the temperature change process, the temperatures of the two must be controlled within a process window of 0~30℃.

[0025] Simply adjusting the In content by controlling the temperature will reduce the In-rich area and increase stress. The present invention adjusts the In content by controlling the temperature and the gas flow rate when growing the InGaN quantum well layer. The gas flow rate can adjust the production rate, make In grow more uniformly, increase more luminous quantum dots, and improve the light efficiency.

[0026] Furthermore, the doping concentration of In in the InGaN quantum well layer is 1E+20~2E+20 atom / cm 3 .

[0027] Furthermore, the growth of the GaN quantum barrier layer is carried out in a reaction chamber at a temperature of 850-910°C and 100-120 Slm of N 2 , 10~30Slm H 2 , 150~200Slm NH 3 , 1200~3000sccm of TMIn and 300~1000sccm of TEGa.

[0028] Furthermore, when growing the GaN quantum barrier layer, the temperature of the reaction chamber is first changed to 850°C within 1 to 3 minutes, and 100 to 120 Slm of N 2 , 10~30Slm H 2 and 150~200Slm NH 3, GaN grows during the change process; then the temperature is raised to 870℃ within 1~2min, and 300~1000sccm of TEGa is introduced, and Si-doped GaN grows during the temperature rising process; then the temperature is raised to 890℃ within 0.5~1min, and 300~1000sccm of TEGa is introduced, and Si-doped GaN grows during the temperature rising process; then the temperature is raised to 910℃ within 0.5~1min, and 5~10sccm of TMAl is introduced, and GaN grows during the temperature rising process; then the temperature is lowered to 850℃ within 1~2min, and 300~1000sccm of TEGa is introduced, and Si-doped GaN grows during the temperature falling process; then the temperature is lowered to 830℃ within 1~3min, and Si-doped GaN grows during the temperature falling process.

[0029] From the above description, it can be seen that the present invention changes the thickness of the V_Pits sidewall by regulating the atmosphere of the barrier layer at different temperatures, which is beneficial to the injection of holes and improves the recombination efficiency of electrons and holes.

[0030] Furthermore, when growing the last GaN quantum barrier layer, TMAl was introduced into the reaction chamber, and the flow rate of TMAl was linearly decreased from 180 sccm to 0 sccm.

[0031] From the above description, it can be seen that by introducing Al when the barrier layer grows at the highest amplitude, a lattice with better quality is obtained, and at the same time the side wall thickness of V_Pits is changed, thereby improving the luminous efficiency; the ratio of the molar number of Al to the molar number of GaN decreases linearly from 15% to 0%, which can maximize the ESD performance and luminous efficiency of the LED.

[0032] Furthermore, the doping concentration of Si in the multi-quantum well light-emitting layer is 1E+16~1E+17atom / cm 3 .

[0033] Furthermore, the thickness of the multi-quantum well light-emitting layer is 0.15-0.2 μm.

[0034] Furthermore, the number of periods of nGaN / GaN in the multi-quantum well light-emitting layer is 10-16.

[0035] Please refer to Figure 1 , further comprising the steps of sequentially growing a buffer layer, a U-type GaN layer, an N-type GaN layer, a multi-quantum well active region layer and a P-type GaN layer on a substrate; the P-type GaN layer comprises a low-temperature P-type GaN layer, a P-type electron blocking layer and a high-temperature P-type GaN layer grown sequentially.

[0036] Furthermore, before growing the buffer layer, the substrate is placed in a reaction chamber, the reaction chamber is first purged with hydrogen, and then the reaction chamber pressure is set to 500-600 mbar and the temperature is set to 1000-1200°C, and the reaction chamber is purged with hydrogen and ammonia for 7-10 minutes.

[0037] From the above description, it can be seen that the present invention improves the quality of the structure subsequently grown on the substrate by removing impurities from the reaction chamber and introducing the gas required for the subsequent reaction in advance for high temperature and high pressure treatment.

[0038] Furthermore, the growth of the buffer layer is carried out in a reaction chamber with a pressure of 100-200 mbar and a temperature of 800-900° C. 60-80 sccm of TMGa and 25-45 sccm of TMAl are introduced for 4-6 minutes.

[0039] It can be seen from the above description that the present invention provides a simple and efficient method for growing a buffer layer, which can grow a high-quality buffer layer.

[0040] Furthermore, the thickness of the buffer layer is 0.01-0.02 μm.

[0041] Furthermore, the growth of the U-type GaN layer is carried out in a reaction chamber with a pressure of 150-500 mbar and a temperature of 900-1100° C. 300-400 sccm of TMGa is introduced for 6-30 minutes.

[0042] It can be seen from the above description that the present invention provides a simple and efficient method for growing a U-type GaN layer, which can grow a high-quality U-type GaN layer.

[0043] Furthermore, the growth of the N-type GaN layer is carried out in a reaction chamber, and the pressure of the reaction chamber is 500-1000 mbar.

[0044] It can be seen from the above description that the present invention provides a simple and efficient method for growing an N-type GaN layer, which can grow a high-quality N-type GaN layer.

[0045] Furthermore, the thickness of the N-type GaN layer is 2-3 μm.

[0046] Furthermore, the growth of the low-temperature P-type GaN layer is carried out in a reaction chamber with a temperature of 700-950°C, a pressure of 300-800 mbar, and a flow of 55,000-65,000 sccm of NH 3 and 25~50sccm TMGa, Mg doping concentration is 1.1~5E+16atom / cm 3 .

[0047] From the above description, it can be seen that the present invention provides a simple and efficient method for preparing the growth of low-temperature P-type GaN. The grown low-temperature P-type GaN can provide holes, protect the multi-quantum well active area from being damaged by high temperature, and can maximize the performance and luminous efficiency of the LED.

[0048] Furthermore, the thickness of the low temperature P-type GaN is 20~80nm.

[0049] Furthermore, the growth of the P-type electron blocking layer is carried out in a reaction chamber at a temperature of 700-950°C and a flow of 30,000-60,000 sccm of NH 3 , 30~50sccm TMGa, 1500~2000sccm Cp 2 Mg and 150~200sccm of TMAl.

[0050] Furthermore, the thickness of the P-type electron blocking layer is 50-70 nm.

[0051] Furthermore, the doping concentration of Mg in the P-type electron blocking layer is 0.5~5E+18 atom / cm 3 , the doping concentration of Al is 1E+17~1E+18 atom / cm 3 .

[0052] It can be seen from the above description that the present invention provides a simple and efficient method for growing a P-type electron blocking layer.

[0053] Furthermore, the growth of the high temperature P-type GaN layer is carried out in a reaction chamber with a temperature of 900-1050°C, a pressure of 600-1000 mbar, and a flow of 60000-75000 sccm of NH 3 , 25~50sccm TMGa and 2000~3000sccm Cp 2 Mg.

[0054] Furthermore, the thickness of the high temperature P-type GaN layer is 60-90 nm.

[0055] Another technical solution adopted by the present invention is: an epitaxial structure is prepared by adopting the above-mentioned growth method of the epitaxial structure for improving the light efficiency of GaN-based epitaxial structure.

[0056] Embodiment 1 of the present invention is: a method for growing an epitaxial structure for improving GaN-based light efficiency, the steps are as follows: S1: placing the substrate into a reaction chamber of a metal organic chemical vapor deposition device, and purging the reaction chamber with hydrogen; S2: Set the reaction chamber pressure to 550 mbar and the temperature to 1100° C., and purge the reaction chamber with hydrogen and ammonia for 8.5 min.

[0057] S3: The pressure of the reaction chamber is set to 150 mbar and the temperature is set to 850° C. 70 sccm of TMGa and 35 sccm of TMAl are introduced for 5 minutes to grow a buffer layer with a thickness of 0.015 μm on the substrate.

[0058] S4: The pressure of the reaction chamber is set to 325 mbar and the temperature is set to 1000° C. 350 sccm of TMGa is introduced for 18 minutes to grow a U-type GaN layer on the buffer layer.

[0059] S5: setting the reaction chamber pressure to 750 mbar, and growing an N-type GaN layer with a thickness of 2.5 μm on the U-type GaN layer.

[0060] S6: Set the temperature of the reaction chamber to 800°C and introduce 40,000 sccm of NH 3 , the doping source is Si doping, and the doping concentration of Si is 1E+17atom / cm 3 , a 15nm thick Si is grown on the N-type GaN layer x N defect inducing layer.

[0061] S7: Set the temperature of the reaction chamber to 800°C and introduce 40,000 sccm of NH 3 , 40sccm TMGa, a 20nm thick current spreading layer is grown on the defect inducing layer, the current spreading layer is Si doped, and the Si doping concentration is 1E+21 atom / cm 3 .

[0062] S8: A multi-quantum well light-emitting layer with a thickness of 0.18 μm is grown on the current spreading layer. The multi-quantum well light-emitting layer is formed by alternating InGaN quantum well layers and GaN quantum barrier layers. The number of cycles is 13, and the growth temperature changes sinusoidally. Figure 2 ; The doping concentration of In in the InGaN quantum well layer is 1E+20~2E+20 atom / cm 3 ; When growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 820°C within 1 minute, and 1200 sccm of TMIn is introduced at the same time. During the change, Si-doped InGaN is grown, and the Si doping concentration is 1E+16atom / cm 3 ; Then the temperature was lowered to 810°C within 1 minute, and 1800 sccm of In was introduced at the same time. During the cooling process, Si-doped InGaN was grown, and the Si doping concentration was 1E+16atom / cm 3; Then the temperature was lowered to 800°C within 0.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the cooling process; then the temperature was lowered to 790°C within 0.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the cooling process; then the temperature was raised to 795°C within 1min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the heating process; then the temperature was raised to 800°C within 2min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the heating process; then the temperature was raised to 825°C within 2min, and 1600sccm of TMIn was introduced at the same time; When growing GaN quantum barrier layers, the temperature of the reaction chamber is first changed to 850°C within 1 minute, and 110 Slm of N 2 , 20Slm H 2 and 170Slm NH 3 , GaN is grown during the change process; then the temperature is raised to 870℃ within 1min, and 700sccm of TEGa is introduced. During the heating process, Si-doped GaN is grown, and the Si doping concentration is 1E+16atom / cm 3 ; Then the temperature was raised to 890°C within 0.5 min, and 700 sccm of TEGa was introduced. During the heating process, Si-doped GaN was grown, and the Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was raised to 910°C within 0.5 min, and 7 sccm of TMAl was introduced to grow GaN during the heating process; Then the temperature was lowered to 850°C within 1 min, and 500 sccm of TEGa was introduced to grow Si-doped GaN during the cooling process. The Si doping concentration was 1E+16atom / cm 3 ; Then the temperature is lowered to 830°C within 1 minute. During the cooling process, Si-doped GaN is grown. The Si doping concentration is 1E+16atom / cm 3 ; When growing the last GaN quantum barrier layer, TMAl was introduced into the reaction chamber, and the flow rate of TMAl decreased linearly from 180 sccm to 0 sccm, and the ratio of the molar number of Al to the molar number of GaN decreased linearly from 15% to 0% in the direction away from the substrate.

[0063] S9: Set the temperature of the reaction chamber to 850°C, the pressure to 550 mbar, and introduce 60,000 sccm of NH 3 and 35sccm of TMGa, with a Mg doping concentration of 4E+16 atom / cm 3 , a low-temperature P-type GaN layer with a thickness of 25 nm is grown on the N-type GaN layer.

[0064] S10: Set the temperature of the reaction chamber to 850°C and introduce 40,000 sccm of NH 3 、40sccm TMGa、1800sccm Cp 2 Mg and 170sccm TMAl, Mg doping concentration is 0.5E+18atom / cm 3 , the Al doping concentration is 1E+17 atom / cm 3 , a P-type electron blocking layer with a thickness of 60nm is grown on the low-temperature P-type GaN layer.

[0065] S11: Set the temperature of the reaction chamber to 955°C, the pressure to 800 mbar, and introduce 67500 sccm of NH 3 , 37.5sccm TMGa and 2500sccm Cp 2 Mg, grow a high-temperature P-type GaN layer with a thickness of 75nm, and complete the preparation of the epitaxial structure.

[0066] Embodiment 2 of the present invention is: The difference between the second embodiment and the first embodiment is that: S7: Set the temperature of the reaction chamber to 800°C and introduce 40,000 sccm of NH 3 , 40sccm TMGa and 180sccm TMAl, a 20nm thick AlGaN current spreading layer is grown on the defect inducing layer, the molar number of Al decreases linearly in the direction facing the substrate, and the Al doping concentration is 2E+19 atom / cm 3 .

[0067] S8: A multi-quantum well light-emitting layer with a thickness of 0.18 μm is grown on the current spreading layer. The multi-quantum well light-emitting layer is formed by alternating InGaN quantum well layers and GaN quantum barrier layers. The number of cycles is 13, and the growth temperature changes sinusoidally. The doping concentration of In in the InGaN quantum well layer is 1E+20~2E+20 atom / cm 3 ; When growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 820°C within 1.5 minutes, and 1200 sccm of TMIn is introduced at the same time. During the change, Si-doped InGaN is grown, and the Si doping concentration is 1E+16atom / cm 3 ; Then the temperature was lowered to 810°C within 1.5 min, and 1800 sccm of In was introduced at the same time. During the cooling process, Si-doped InGaN was grown, and the Si doping concentration was 1E+16atom / cm 3; Then the temperature was lowered to 800°C within 0.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the cooling process; Then the temperature was lowered to 790°C within 0.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the cooling process; Then the temperature was raised to 795°C within 1.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the heating process; Then the temperature was lowered to 800°C within 1.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the cooling process; Then the temperature was raised to 825°C within 1.5min, and 1600sccm of TMIn was introduced at the same time; When growing GaN quantum barrier layers, the temperature of the reaction chamber was first changed to 850°C within 1.5 min, and 110 Slm of N 2 , 20Slm H 2 and 170Slm NH 3 , GaN is grown during the change process; then the temperature is raised to 870℃ within 1min, and 700sccm of TEGa is introduced. During the heating process, Si-doped GaN is grown, and the Si doping concentration is 1E+16atom / cm 3 ; Then the temperature was raised to 890°C within 0.5 min, and 700 sccm of TEGa was introduced. During the heating process, Si-doped GaN was grown, and the Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was raised to 910°C within 1 minute, and 7sccm of TMAl was introduced to grow GaN during the heating process; Then the temperature was lowered to 850°C within 1.5 minutes, and 700ccm of TEGa was introduced to grow Si-doped GaN during the cooling process. The Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was lowered to 830°C within 1.5 min. During the cooling process, Si-doped GaN was grown. The Si doping concentration was 1E+16atom / cm 3 ; When growing the last GaN quantum barrier layer, TMAl was introduced into the reaction chamber, and the flow rate of TMAl decreased linearly from 180 sccm to 0 sccm, and the ratio of the molar number of Al to the molar number of GaN decreased linearly from 15% to 0% in the direction away from the substrate.

[0068] Embodiment 3 of the present invention is: The difference between the third embodiment and the first embodiment is that: S6: Set the temperature of the reaction chamber to 800°C and introduce 40,000 sccm of NH 3 , 40sccm TMGa and 1300sccm TMIn, Si doped In with a thickness of 150nm is grown on the N-type GaN layery GaN defect induction layer, Si doping concentration 1E+21atom / cm 3 , the doping concentration of In is 1E+20atom / cm 3 .

[0069] S7: Set the temperature of the reaction chamber to 800°C and introduce 40,000 sccm of NH 3 , 40sccm TMGa and 180sccm TMAl, a 20nm thick AlGaN current spreading layer is grown on the defect inducing layer, the molar number of Al decreases linearly in the direction facing the substrate, and the Al doping concentration is 2E+19 atom / cm 3 .

[0070] S8: A multi-quantum well light-emitting layer with a thickness of 0.18 μm is grown on the current spreading layer. The multi-quantum well light-emitting layer is formed by alternating InGaN quantum well layers and GaN quantum barrier layers. The number of cycles is 13, and the growth temperature changes sinusoidally. The doping concentration of In in the InGaN quantum well layer is 1E+20~2E+20 atom / cm 3 ; When growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 820°C within 2 minutes, and 1200 sccm of TMIn is introduced at the same time. During the change, Si-doped InGaN is grown, and the Si doping concentration is 1E+16atom / cm 3 Then the temperature was lowered to 810°C within 2 minutes, and 1800 sccm of In was introduced at the same time. During the cooling process, Si-doped InGaN was grown, and the Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was lowered to 800°C within 1 minute, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the cooling process; then the temperature was lowered to 790°C within 0.5 minute, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the cooling process; then the temperature was raised to 795°C within 1 minute, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the heating process; then the temperature was raised to 800°C within 2 minutes, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the heating process; then the temperature was raised to 825°C within 2 minutes, and 1600 sccm of TMIn was introduced at the same time; When growing GaN quantum barrier layers, the temperature of the reaction chamber was first changed to 850°C within 1.5 min, and 110 Slm of N 2 , 20Slm H 2 and 170Slm NH 3, GaN is grown during the change process; then the temperature is raised to 870℃ within 1min, and 700sccm of TEGa is introduced. During the heating process, Si-doped GaN is grown, and the Si doping concentration is 1E+16atom / cm 3 Then the temperature was raised to 890°C within 0.5 min, and 700 sccm of TEGa was introduced. During the heating process, Si-doped GaN was grown, and the Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was raised to 910°C within 1 minute, and 7 sccm of TMAl was introduced to grow GaN during the heating process; Then the temperature was lowered to 850°C within 1.5 minutes, and 700 sccm of TEGa was introduced to grow Si-doped GaN during the cooling process. The Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was lowered to 830°C within 1.5 min. During the cooling process, Si-doped GaN was grown. The Si doping concentration was 1E+16atom / cm 3 ; When growing the last GaN quantum barrier layer, TMAl was introduced into the reaction chamber, and the flow rate of TMAl decreased linearly from 180 sccm to 0 sccm, and the ratio of the molar number of Al to the molar number of GaN decreased linearly from 15% to 0% in the direction away from the substrate.

[0071] Comparative Example 1 of the present invention is: using a rectangular temperature growth curve (see Figure 3 ) growing a multi-quantum well light-emitting layer; The difference between the comparative example 1 and the example 3 is that: S8: A multi-quantum well light-emitting layer with a thickness of 0.18 μm is grown on the current spreading layer. The multi-quantum well light-emitting layer is formed by alternating InGaN quantum well layers and GaN quantum barrier layers. The number of cycles is 13, and the growth temperature changes sinusoidally. The doping concentration of In in the InGaN quantum well layer is 1E+20~2E+20 atom / cm 3 ; When growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 790°C within 3 minutes, without growth, and kept warm for 0.5 minutes; then the temperature is kept constant within 2 minutes, 2400 sccm of TMIn is introduced, and InGaN is grown; then the temperature is raised to 825°C within 1 minute, 1600 sccm of TMIn is introduced, and InGaN is grown during the temperature rise process. ; When growing GaN quantum barrier layers, the temperature of the reaction chamber was first changed to 850°C within 1.5 min, and 110 Slm of N 2 , 20Slm H 2 and 170Slm NH 3, GaN is grown during the change process; then the temperature is raised to 870℃ within 1min, and 700sccm of TEGa is introduced. During the heating process, Si-doped GaN is grown, and the Si doping concentration is 1E+16atom / cm 3 ; Then the temperature was raised to 890°C within 0.5 min, and 700 sccm of TEGa was introduced. During the heating process, Si-doped GaN was grown, and the Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was raised to 910°C within 1 minute, and 7 sccm of TMAl was introduced to grow GaN during the heating process; then the temperature was lowered to 790°C within 3 minutes; When growing the last GaN quantum barrier layer, TMAl was introduced into the reaction chamber, and the flow rate of TMAl decreased linearly from 180 sccm to 0 sccm, and the ratio of the molar number of Al to the molar number of GaN decreased linearly from 15% to 0% in the direction away from the substrate.

[0072] The epitaxial wafers grown in Examples 1 to 3 and Comparative Example 1 were prepared into 23mil*56mil chips and tested at 60ma. The test results are shown in Table 1.

[0073] Table 1

[0074] As can be seen from Table 1, the light efficiency is significantly improved when the epitaxial structure obtained by the growth method of the present invention is prepared into a chip.

[0075] Embodiment 5 of the present invention is: a method for growing an epitaxial structure for improving GaN-based light efficiency, the steps are as follows: S1: placing the substrate into a reaction chamber of a metal organic chemical vapor deposition device, and purging the reaction chamber with hydrogen; S2: Place the substrate into the reaction chamber, set the pressure of the reaction chamber to 500 mbar and the temperature to 1000° C., and purge the reaction chamber with hydrogen and ammonia for 7 minutes.

[0076] S3: The pressure of the reaction chamber is set to 100 mbar and the temperature is set to 800° C. 60 sccm of TMGa and 25 sccm of TMAl are introduced for 4 minutes to grow a buffer layer with a thickness of 0.01 μm on the substrate.

[0077] S4: The pressure of the reaction chamber is set to 150 mbar and the temperature is set to 900° C. 300 sccm of TMGa is introduced for 6 minutes to grow a U-type GaN layer on the buffer layer.

[0078] S5: setting the pressure of the reaction chamber to 500 mbar, and growing an N-type GaN layer with a thickness of 2 μm on the U-type GaN layer.

[0079] S6: Set the temperature of the reaction chamber to 700°C and introduce 30,000 sccm of NH 3 , a defect-inducing layer with a thickness of 2 nm is grown on the N-type GaN layer.

[0080] S7: Set the temperature of the reaction chamber to 700°C and introduce 30,000 sccm of NH 3 , 30~50sccm TMGa and 150sccm TMAl, a 10nm thick current spreading layer is grown on the defect inducing layer. The current spreading layer is Si-doped AlGaN with a doping concentration of 1E+20 atom / cm 3 , the molar number of Al in the current spreading layer decreases linearly in the direction close to the substrate.

[0081] S8: A multi-quantum well light-emitting layer with a thickness of 0.2 μm is grown on the current spreading layer. The multi-quantum well light-emitting layer is formed by alternating InGaN quantum well layers and GaN quantum barrier layers. The number of cycles is 16, and the growth temperature changes sinusoidally. The doping concentration of In in the InGaN quantum well layer is 2E+20 atom / cm 3 , When growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 820°C within 2 minutes, and 1200 sccm of TMIn is introduced at the same time. During the change process, Si-doped InGaN is grown, and the Si doping concentration is 1E+17atom / cm 3 ; Then the temperature was lowered to 810°C within 2 minutes, and 1800 sccm of In was introduced at the same time. During the cooling process, Si-doped InGaN was grown, and the Si doping concentration was 1E+17atom / cm 3 ; Then the temperature was lowered to 800°C within 1 minute, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the cooling process; then the temperature was lowered to 790°C within 1 minute, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the cooling process; then the temperature was raised to 795°C within 1 minute, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the heating process; then the temperature was raised to 800°C within 2 minutes, and 2400 sccm of TMIn was introduced at the same time, and InGaN grew during the heating process; then the temperature was raised to 825°C within 2 minutes, and 1600 sccm of TMIn was introduced at the same time; When growing GaN quantum barrier layers, the temperature of the reaction chamber was first changed to 850°C within 3 minutes, and 120 Slm of N 2 , 30Slm H 2 and 200Slm NH 3, GaN is grown during the change process; then the temperature is raised to 870℃ within 2min, and 1000sccm of TEGa is introduced. During the heating process, Si-doped GaN is grown, and the Si doping concentration is 1E+17atom / cm 3 Then the temperature was raised to 890°C within 1 minute, and 1000 sccm of TEGa was introduced. During the heating process, Si-doped GaN was grown, and the Si doping concentration was 1E+17atom / cm 3 ; Then the temperature was raised to 910°C within 1 minute, and 10 sccm of TMAl was introduced to grow GaN during the heating process; Then the temperature was lowered to 850°C within 2 minutes, and 1000 sccm of TEGa was introduced to grow Si-doped GaN during the cooling process. The Si doping concentration was 1E+17atom / cm 3 ; Then the temperature is lowered to 830°C within 1-3 minutes. During the cooling process, Si-doped GaN is grown. The Si doping concentration is 1E+17atom / cm 3 ; When growing the last GaN quantum barrier layer, TMAl was introduced into the reaction chamber, and the flow rate of TMAl decreased linearly from 180 sccm to 0 sccm, and the ratio of the molar number of Al to the molar number of GaN decreased linearly from 15% to 0% in the direction away from the substrate.

[0082] S9: Set the temperature of the reaction chamber to 700°C, the pressure to 300 mbar, and introduce 55,000 sccm of NH 3 and 25sccm of TMGa, with a Mg doping concentration of 1.1E+16 atom / cm 3 , a low-temperature P-type GaN layer with a thickness of 20 nm is grown on the N-type GaN layer.

[0083] S10: Set the temperature of the reaction chamber to 700°C and introduce 30,000 sccm of NH 3 , 30sccm TMGa, 150sccm TMAl, Al doping concentration is 1E+17 atom / cm 3 , a P-type electron blocking layer with a thickness of 50 nm is grown on the low-temperature P-type GaN layer.

[0084] S11: Set the temperature of the reaction chamber to 900°C, the pressure to 600 mbar, and introduce 60,000 sccm of NH 3 , 25sccm TMGa and 2000sccm Cp 2 Mg, grow a high-temperature P-type GaN layer with a thickness of 60nm, and complete the preparation of the epitaxial structure.

[0085] Embodiment 6 of the present invention is: a method for growing an epitaxial structure for improving GaN-based light efficiency, the steps are as follows: S1: placing the substrate into a reaction chamber of a metal organic chemical vapor deposition device, and purging the reaction chamber with hydrogen; S2: Place the substrate into the reaction chamber, set the pressure of the reaction chamber to 600 mbar and the temperature to 1200° C., and purge the reaction chamber with hydrogen and ammonia for 10 minutes.

[0086] S3: The pressure of the reaction chamber is set to 200 mbar and the temperature is set to 900° C. 80 sccm of TMGa and 45 sccm of TMAl are introduced for 6 minutes to grow a buffer layer with a thickness of 0.02 μm on the substrate.

[0087] S4: The pressure of the reaction chamber is set to 500 mbar and the temperature is set to 1100° C. 400 sccm of TMGa is introduced for 30 minutes to grow a U-type GaN layer on the buffer layer.

[0088] S5: setting the reaction chamber pressure to 1000 mbar, and growing an N-type GaN layer with a thickness of 3 μm on the U-type GaN layer.

[0089] S6: Set the temperature of the reaction chamber to 950°C and introduce 60,000 sccm of NH 3 , a defect-inducing layer with a thickness of 30 nm is grown on the N-type GaN layer.

[0090] S7: Set the temperature of the reaction chamber to 950°C and introduce 60,000 sccm of NH 3 , 50sccm TMGa and 200sccm TMAl, a 30nm thick current spreading layer is grown on the defect inducing layer. The current spreading layer is Si-doped AlGaN with a doping concentration of 2E+16 atom / cm 3 , the molar number of Al in the current spreading layer decreases linearly in the direction close to the substrate.

[0091] S8: A multi-quantum well light-emitting layer with a thickness of 0.15 μm is grown on the current spreading layer. The multi-quantum well light-emitting layer is formed by alternating InGaN quantum well layers and GaN quantum barrier layers. The number of cycles is 10, and the growth temperature changes sinusoidally. The doping concentration of In in the InGaN quantum well layer is 1E+20 atom / cm 3 , When growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 820°C within 1 minute, and 1200 sccm of TMIn is introduced at the same time. During the change, Si-doped InGaN is grown, and the Si doping concentration is 1E+16atom / cm 3; Then the temperature was lowered to 810°C within 1 minute, and 1800 sccm of In was introduced at the same time. During the cooling process, Si-doped InGaN was grown, and the Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was lowered to 800°C within 0.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the cooling process; then the temperature was lowered to 790°C within 0.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the cooling process; then the temperature was raised to 795°C within 0.5min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the heating process; then the temperature was raised to 800°C within 1min, and 2400sccm of TMIn was introduced at the same time, and InGaN was grown during the heating process; then the temperature was raised to 825°C within 1min, and 1600sccm of TMIn was introduced at the same time; When growing GaN quantum barrier layers, the temperature of the reaction chamber is first changed to 850°C within 1 minute, and 100 Slm of N 2 , 10Slm H 2 and 150Slm NH 3 , GaN is grown during the change process; then the temperature is raised to 870℃ within 1min, and 300sccm of TEGa is introduced. During the heating process, Si-doped GaN is grown, and the Si doping concentration is 1E+16atom / cm 3 Then the temperature was raised to 890°C within 0.5 min, and 300 sccm of TEGa was introduced. During the heating process, Si-doped GaN was grown, and the Si doping concentration was 1E+16atom / cm 3 ; Then the temperature was raised to 910°C within 0.5 min, and 5 sccm of TMAl was introduced to grow GaN during the heating process; Then the temperature was lowered to 850°C within 1 min, and 300 sccm of TEGa was introduced to grow Si-doped GaN during the cooling process. The Si doping concentration was 1E+16atom / cm 3 ; Then the temperature is lowered to 830°C within 1 minute. During the cooling process, Si-doped GaN is grown. The Si doping concentration is 1E+16atom / cm 3 ; When growing the last GaN quantum barrier layer, TMAl was introduced into the reaction chamber, and the flow rate of TMAl decreased linearly from 180 sccm to 0 sccm, and the ratio of the molar number of Al to the molar number of GaN decreased linearly from 15% to 0% in the direction away from the substrate.

[0092] S9: Set the temperature of the reaction chamber to 950°C, the pressure to 800 mbar, and introduce 65,000 sccm of NH 3and 25~50sccm TMGa, Mg doping concentration is 1.1~5E+16 atom / cm 3 , a low-temperature P-type GaN layer with a thickness of 30nm is grown on the N-type GaN layer.

[0093] S10: Set the temperature of the reaction chamber to 950°C and introduce 60,000 sccm of NH 3 、50sccm TMGa、2000sccm Cp 2 Mg and 200 sccm TMAl, Mg doping concentration is 5E+18 atom / cm 3 , the Al doping concentration is 1E+18 atom / cm 3 , a P-type electron blocking layer with a thickness of 70nm is grown on the low-temperature P-type GaN layer.

[0094] S11: Set the temperature of the reaction chamber to 1050°C, the pressure to 1000 mbar, and introduce 75000 sccm of NH 3 , 50sccm TMGa and 3000sccm Cp 2 Mg, grow a high-temperature P-type GaN layer with a thickness of 90nm, and complete the preparation of the epitaxial structure.

[0095] Please refer to Figure 1 Embodiment 6 of the present invention is: an epitaxial structure prepared by the growth method of embodiment 1, the epitaxial structure includes a substrate 1, a buffer layer 2, a U-type GaN layer 3, an N-type GaN layer 4, a defect inducing layer 5, a current spreading layer 6, a multi-quantum well light-emitting layer 7, a low-temperature P-type GaN layer 8, a P-type electron blocking layer 9 and a high-temperature P-type GaN layer 10 stacked in sequence.

[0096] In summary, the epitaxial structure and growth method for improving GaN-based light efficiency provided by the present invention adopt positive temperature change and adjust the introduced Group V gas at the same time when growing the multi-quantum well light-emitting layer, thereby reducing the aggregation of In, reducing stress, and improving the crystal quality; doping a small amount of Si at the lowest amplitude improves the injection efficiency of electrons, can change the size of V_Pits, reduce the temperature overshoot, and reduce V_Pits, effectively delaying the generation of V-type defects; wherein the barrier layer adjusts different temperatures and different atmospheres, changes the thickness of the V_Pits side wall, is beneficial to the injection of holes, improves the recombination efficiency of electrons and holes, and increases the voltage under small currents to achieve the purpose of improving light efficiency.

[0097] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for growing an epitaxial structure for improving GaN-based light efficiency, characterized in that: The method comprises the steps of growing a multi-quantum well active region layer, wherein the growing of the multi-quantum well active region layer comprises the following steps: sequentially growing a defect inducing layer, a current spreading layer and a multi-quantum well light-emitting layer, wherein the multi-quantum well light-emitting layer comprises alternating layers of InGaN quantum well layers and GaN quantum barrier layers, and the growth temperature and In content vary sinusoidally.

2. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 1, characterized in that: The defect inducing layer is made of heavily doped N-compound.

3. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 1, characterized in that: The material of the current spreading layer is GaN doped with any one of Si, In, Al and Mg doping sources.

4. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 3, characterized in that: When the doping source in the current spreading layer is Al, the molar number of Al decreases linearly in the direction approaching the substrate.

5. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 1, characterized in that: The InGaN quantum well layer is grown in a reaction chamber, the temperature of the reaction chamber is 790-850° C., and 1200-3000 sccm of TMIn is introduced.

6. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 5, characterized in that: When growing the InGaN quantum well layer, the temperature of the reaction chamber is first changed to 820°C within 1-2 minutes, and 1200 sccm of TMIn is introduced at the same time, and Si-doped InGaN grows during the change process; then the temperature is lowered to 810°C within 1-2 minutes, and 1800 sccm of In is introduced at the same time, and Si-doped InGaN grows during the cooling process; then the temperature is lowered to 800°C within 0.5-1 minute, and 2400 sccm of TMIn is introduced at the same time, and InGaN grows during the cooling process; then the temperature is lowered to .... The temperature is lowered to 790°C within 0.5~1min, and 2400sccm of TMIn is introduced at the same time, and InGaN grows during the cooling process; the temperature is then raised to 795°C within 0.5~1min, and 2400sccm of TMIn is introduced at the same time, and InGaN grows during the heating process; the temperature is then raised to 800°C within 1~2min, and 2400sccm of TMIn is introduced at the same time, and InGaN grows during the heating process; the temperature is then raised to 825°C within 1~2min, and 1600sccm of TMIn is introduced at the same time.

7. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 1, characterized in that: The growth of the GaN quantum barrier layer is carried out in a reaction chamber, the temperature of the reaction chamber is 850-910° C., and 100-120 Slm of N2, 10-30 Slm of H2, 150-200 Slm of NH3, 1200-3000 sccm of TMIn and 300-1000 sccm of TEGa are introduced.

8. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 7, characterized in that: When growing the GaN quantum barrier layer, the temperature of the reaction chamber is first changed to 850°C within 1-3 minutes, and 100-120 Slm of N2, 10-30 Slm of H2 and 150-200 Slm of NH3 are introduced at the same time, and GaN grows during the change process; then the temperature is raised to 870°C within 1-2 minutes, and 300-1000 sccm of TEGa is introduced, and Si-doped GaN grows during the temperature rise process; then the temperature is raised to 890°C within 0.5-1 minute, and 300-1000 sccm of TEGa is introduced, and Si-doped GaN grows during the temperature rise process; then the temperature is raised to 910°C within 0.5-1 minute, and 5-10 sccm of TMAl is introduced, GaN is grown during the heating process; then the temperature is lowered to 850°C within 1 to 2 minutes, and 300 to 1000 sccm of TEGa is introduced, and Si-doped GaN is grown during the cooling process; then the temperature is lowered to 830°C within 1 to 3 minutes, and Si-doped GaN is grown during the cooling process.

9. The method for growing an epitaxial structure for improving GaN-based light efficiency according to claim 1, characterized in that: When growing the last GaN quantum barrier layer, TMAl is introduced into the reaction chamber, and the flow rate of TMAl is linearly reduced from 180 sccm to 0 sccm.

10. An epitaxial structure prepared by the growth method of an epitaxial structure for improving GaN-based light efficiency as claimed in any one of claims 1 to 9.

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