GaN-based epitaxial structure and method for growing the same

Abstract

The application relates to the technical field of LED chips, in particular to a GaN-based epitaxial structure and a growth method thereof. The GaN-based epitaxial structure comprises an AlN layer, a buffer layer, a U-shaped GaN layer, an N-type GaN layer, a stress release layer and a multi-quantum-step active region layer which are sequentially grown on a substrate, and a low-temperature P-type GaN layer, a current blocking layer and a high-temperature P-type GaN layer are sequentially grown on the multi-quantum-step active region layer. The GaN-based epitaxial structure optimizes the Al and IN components of the current blocking layer in the GaN-based epitaxial structure to form a sectional doping, the sectional doping current blocking layer can not only inhibit the extension of dislocations in quantum wells, so that the quality of the epitaxial wafer is improved, but also can effectively inhibit the overflow of the current, reduce the electron transition, and the purpose of improving the light efficiency is achieved.

Description

Technical Field

[0001] This invention relates to the field of LED chip technology, specifically to a GaN-based epitaxial structure and its growth method. Background Technology

[0002] In recent years, the market has had an urgent need for high-quality, high-reliability, and high-efficiency GaN (gallium nitride)-based LED (light-emitting diode) chips, making research on improving the luminous efficiency and brightness of LEDs imperative.

[0003] Currently, the epitaxial structure of GaN-based LEDs consists of the following layers: substrate, AlN (aluminum nitride) layer, buffer layer, U-type GaN layer, N-type GaN layer, stress relief layer, MQW (multi-quantum-level) active region, and P-type layer. When current flows, electrons in the N-type region and holes in the P-type region enter the MQW active region and recombine, emitting visible light in the desired wavelength range. Therefore, the brightness of most GaN-based LED chips depends critically on the N-type and P-type region structures, especially on the quality of their N-type and P-type doping.

[0004] Taking GaN wide-gap semiconductor as an example, although the N-type GaN layer has good N-type conductivity, it is plagued by the problem of doping asymmetry, resulting in a small number of holes and a low hole concentration in the quantum well, which leads to low conductivity of the P-type GaN layer and reduces light efficiency and brightness. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a GaN-based epitaxial structure with high brightness and high luminous efficiency and its growth method.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a GaN-based epitaxial structure, comprising an AlN layer, a buffer layer, a U-type GaN layer, an N-type GaN layer, a stress relief layer and a multi-quantum-order active region layer grown sequentially on a substrate, wherein a low-temperature P-type GaN layer, a current blocking layer and a high-temperature P-type GaN layer are sequentially grown on the multi-quantum-order active region layer.

[0007] Another technical solution adopted in this invention is: a method for growing a GaN-based epitaxial structure, including a current blocking layer, wherein the preparation of the current blocking layer includes three stages:

[0008] First stage: Simultaneously introduce a TMIN (trimethylindium) source at 250-350 sccm and a TMAl (trimethylaluminum) source at 70-80 sccm, with the introduction time of the TMIN source and the TMAl source being equal.

[0009] Second stage: Simultaneously introduce a TMIN source of 250-350 sccm and a TMA1 source of 30-40 sccm, with the introduction time of the TMIN source and the TMA1 source being equal.

[0010] Phase 3: Simultaneously introduce a TMIN source of 800-1000 sccm and turn off the TMA1 source.

[0011] The beneficial effects of this invention are as follows: This invention optimizes the Al and IN composition of the current blocking layer in the GaN-based epitaxial structure to form a segmented doping layer. This segmented doped current blocking layer can not only suppress the extension of dislocations in the quantum well, thereby improving the quality of the epitaxial wafer, but also effectively suppress current overflow and reduce electron transitions, thus achieving the goal of improving optical efficiency. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the GaN-based epitaxial structure in a specific embodiment of the present invention;

[0013] Figure 2 This is a voltage comparison graph between Example 1 and Comparative Example 1;

[0014] Figure 3 This is a brightness comparison chart of Example 1 and Comparative Example 1. Detailed Implementation

[0015] To explain in detail the technical content, objectives, and effects of the present invention, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0016] Please refer to Figure 1 A GaN-based epitaxial structure includes an AlN layer, a buffer layer, a U-type GaN layer, an N-type GaN layer, a stress relief layer, and a multi-quantum-order active region layer sequentially grown on a substrate. A low-temperature P-type GaN layer, a current-blocking layer, and a high-temperature P-type GaN layer are sequentially grown on the multi-quantum-order active region layer.

[0017] As can be seen from the above description, the beneficial effects of the present invention are as follows: the epitaxial structure forms a segmented doped current blocking layer with varying concentrations in P-type GaN at low temperature, ionizing more holes, thereby increasing the hole concentration in the quantum well and making it more compatible with the electron concentration. This effectively reduces electron transitions in the high-efficiency structure and improves brightness while ensuring electrical properties.

[0018] Another technical solution adopted in this invention is: a method for growing GaN-based epitaxial structures, including a current blocking layer, the preparation of which includes three stages:

[0019] Phase 1: Simultaneously introduce a TMIN source of 250-350 sccm and a TMA1 source of 70-80 sccm, with the introduction duration of the TMIN source and the TMA1 source being equal.

[0020] Second stage: Simultaneously introduce a TMIN source of 250-350 sccm and a TMA1 source of 30-40 sccm, with the introduction time of the TMIN source and the TMA1 source being equal.

[0021] Phase 3: Simultaneously introduce a TMIN source of 800-1000 sccm and turn off the TMA1 source.

[0022] As described above, this invention addresses the current blocking layer in GaN-based epitaxial structures by employing a stepped TMIN / TMAl source process. Different amounts of TMAl and TMIN sources are introduced to optimize the Al and IN composition, resulting in segmented doped current blocking layers with varying concentrations. This segmented doped current blocking layer not only suppresses dislocation propagation in the quantum well, confining electrons to a fixed region and improving the quality of the epitaxial wafer, but also ionizes more holes, increasing the hole concentration in the quantum well and better matching it with the electron concentration. Higher-energy blocked electrons can directly enter the P-layer, effectively suppressing current overflow and reducing electron transitions while maintaining electrical properties, thereby improving brightness and luminous efficiency.

[0023] The TMIN and TMAl sources in each of the three stages have specific combinations. Excessive IN content in each stage will lead to ESD (electrostatic discharge) abnormalities, while excessive Al content will lead to voltage abnormalities. Changing the TMIN and TMAl source contents in each stage will cause an imbalance in the current blocking layer configuration with smaller electrical windows, thereby reducing the LED's electrical properties and luminous efficacy. The three stages have different functions: the first stage is a hole-doped layer, which plays the role of heavy hole doping; the second stage can raise the potential barrier, confining the charge carriers within the MQW; the third stage further raises the potential barrier to obtain a complete current blocking layer. The positions of the three stages cannot be interchanged; interchangement will not achieve the effect of raising the potential barrier.

[0024] Furthermore, the duration of the first stage is 60–90 seconds, the duration of the second stage is 180–240 seconds, and the duration of the third stage is 60–80 seconds.

[0025] As can be seen from the above description, the three stages of time control the thickness of the growth, and each layer can only improve performance within the corresponding thickness range.

[0026] Furthermore, the growth of the current blocking layer is carried out in a reaction chamber, with the temperature set at 700–800°C and the pressure at 300–800 mbar.

[0027] As can be seen from the above description, increased temperature and pressure will cause the layer structure to grow too fast, and vice versa. Both too fast and too slow growth will affect the crystal quality of the grown layers.

[0028] Furthermore, during the growth of the current blocking layer, 55,000–65,000 sccm of NH3, 600–700 sccm of CP2Mg (magnesium pyrocene), and 120–150 sccm of TMGa source are continuously introduced into the reaction chamber.

[0029] As can be seen from the above description, the ratio of the introduced substance is fixed. Changes in this ratio will lead to a significant decrease in luminous efficacy, a reduction in brightness, and an increase in voltage.

[0030] Furthermore, an AlN layer, a buffer layer, a U-type GaN layer, an N-type GaN layer, a stress relief layer, a multi-quantum-level active region layer, a low-temperature P-type GaN layer, a current blocking layer, and a high-temperature P-type GaN layer are sequentially grown on the substrate.

[0031] As can be seen from the above description, the GaN-based epitaxial structure of the present invention is formed by step-doping Al and IN in the low-temperature section of P-type GaN to form a segmented doped current blocking layer with different concentrations. This current blocking layer not only suppresses the extension of dislocations in the quantum well, thereby improving the quality of the epitaxial wafer, but also effectively suppresses current overflow and reduces electron transitions, thus achieving the purpose of improving optical efficiency.

[0032] Furthermore, the multi-quantum hierarchy includes 10 to 16 cycles of sequentially stacked InGaN and GaN layers.

[0033] As can be seen from the above description, both too many and too few cycles will result in poor luminous efficacy.

[0034] Furthermore, during the growth of the InGaN layer, a TMIN source of 1200–1500 sccm and a TMGa source of 25–40 sccm are introduced.

[0035] When growing the GaN layer, turn off the TMIN source and introduce a TMGa source of 25-40 sccm.

[0036] Furthermore, the growth of multiple quantum levels is carried out in a reaction chamber, with the temperature set at 700–800°C and the pressure at 500–1000 mbar.

[0037] As can be seen from the above description, by designing a segmented growth structure of quantum wells and adjusting the IN content at temperature, well-barrier mismatch can be reduced, thereby alleviating the Stark effect, reducing dislocations, and improving luminescence efficiency.

[0038] Please refer to Figure 1 Embodiment 1 of the present invention is: a GaN-based epitaxial structure, comprising, from top to bottom, an AlN layer, a buffer layer, a U-type GaN layer, an N-type GaN layer, a stress relief layer, a multi-quantum-level active region layer, a low-temperature P-type GaN layer, a current blocking layer and a high-temperature P-type GaN layer on a sapphire substrate.

[0039] Embodiment 2 of the present invention is: a method for growing a GaN-based epitaxial structure, comprising the following steps:

[0040] S1: Using a sapphire substrate, the substrate is placed in the reaction chamber of a metal-organic chemical vapor deposition (MOCVD) device. The pressure in the reaction chamber is 550 mbar and the temperature is 1100 °C. H2 is used as the carrier gas for substrate surface treatment. The duration of this process is 11 min.

[0041] S2: Reduce the pressure in the reaction chamber to 150 mbar and the temperature to 850 °C. Using H2 and NH3 as supports, introduce a 110 sccm TMGa source and a 90 sccm TMAl source, and simultaneously introduce a TMIN source to grow a buffer layer with a thickness of 0.15 μm on the substrate.

[0042] S3: Raise the temperature to 1100℃, adjust the pressure in the reaction chamber to 200mbar, and introduce an 800sccm TMGa source. This process lasts for 8 minutes, forming a 3μm thick U-shaped GaN layer on the buffer layer.

[0043] S4: Increase the pressure in the reaction chamber to 700 mbar, set the temperature to 1100℃, and introduce 50000 sccm of NH3, 15000 sccm of H2, 50000 sccm of N2, and 1000 sccm of TMGa source to grow an N-type GaN layer with a thickness of 2.5 μm on the U-type GaN layer.

[0044] S5: Set the reaction chamber temperature to 800℃ and the pressure to 200mbar. Introduce 70000sccm of NH3, 10000sccm of H2 and 70000sccm of N2. Introduce 1000sccm of TEGa (triethylgallium) source. Introduce 300sccm of TMIN source intermittently every 15s to grow a stress relief layer with a thickness of 200nm on the N-type GaN layer.

[0045] S6: Set the reaction chamber pressure to 800 mbar and temperature to 750℃. Introduce 40,000 sccm of NH3, 15,000 sccm of H2, 40,000 sccm of N2, and 30 sccm of TMGa source to grow a periodic InGaN / GaN multi-quantum-well active region layer on the stress-relieving layer. The InGaN / GaN period number is 13. The thickness of the multi-quantum-well active region layer is 0.18 μm, and the In doping concentration is 1.5E+20 atom / cm. 3 During the growth of IngaN / GaN, a TMIN source of 1300 sccm was also introduced into the IngaN layer.

[0046] S7: Set the reaction chamber pressure to 600 mbar and temperature to 650 °C, and introduce 60,000 sccm of NH3 and 40 sccm of TMGa source to form a low-temperature P-type GaN layer with a thickness of 70 Nm on the multi-quantum well active region layer.

[0047] S8: Set the reaction chamber pressure to 600 mbar and temperature to 750℃, and introduce 60000 sccm of NH3, 650 sccm of CP2Mg source and 130 sccm of TMGa source. At the same time, perform segmented doping to grow a current blocking layer on the low-temperature P-type GaN layer.

[0048] The segmented doping process involves introducing TMIN and TMAl sources of different concentrations in three stages.

[0049] The first stage involves introducing a TMIN source at 300 sccm and a TMA1 source at 75 sccm simultaneously for 80 seconds.

[0050] The second stage involves introducing a 300 sccm TMIN source and simultaneously introducing a 35 sccm TMA1 source for 200 seconds.

[0051] The third stage involves introducing a TMIN source at 900 sccm and shutting off the TMA1 source; this process lasts 70 seconds.

[0052] S9: Finally, the reaction chamber temperature is raised to 1000℃ and the pressure to 800mbar. A 65000sccm source of NH3, a 40sccm source of TMGa, and a 2500sccm source of CP2Mg are introduced to form a high-temperature P-type GaN layer with a thickness of 80Nm on the current blocking layer. The Mg doping concentration in the high-temperature P-type GaN layer is 1E+20atom / cm³. 3 .

[0053] S10: Lower the temperature of the reaction chamber and perform annealing in a N2 atmosphere at a temperature of 700℃ for 10 minutes. Then lower the temperature to room temperature to complete the epitaxial growth.

[0054] Embodiment 3 of the present invention is: a method for growing a GaN-based epitaxial structure, comprising the following steps:

[0055] S1: Using a sapphire substrate, the substrate is placed in the reaction chamber of a metal-organic chemical vapor deposition (MOCVD) device. The pressure in the reaction chamber is 500 mbar and the temperature is 1200 °C. H2 is used as the carrier gas for substrate surface treatment. The duration of this process is 10 minN.

[0056] S2: Reduce the pressure in the reaction chamber to 100 mbar and the temperature to 900 °C. Using H2 and NH3 as carriers, introduce a 100 sccm TMGa source and an 80 sccm TMAl source, while simultaneously introducing a TMIN source. This process lasts for 4 minutes, during which a buffer layer with a thickness of 0.1 μm is grown on the substrate.

[0057] S3: Raise the temperature to 1000℃, adjust the pressure in the reaction chamber to 250mbar, and introduce a 650sccm TMGa source. This process lasts for 6 minutes, forming a U-shaped GaN layer with a thickness of 2μm on the buffer layer.

[0058] S4: Increase the pressure in the reaction chamber to 500 mbar, set the temperature to 1100℃, and introduce 50000 sccm of NH3, 15000 sccm of H2, 50000 sccm of N2, and 1000 sccm of TMGa source to grow an N-type GaN layer with a thickness of 2 μm on the U-type GaN layer.

[0059] S5: Set the reaction chamber temperature to 750℃ and the pressure to 350mbar. Introduce 60000sccm of NH3, 5000sccm of H2 and 60000sccm of N2, and introduce 500sccm of TEGa source. Introduce 100sccm of TMIN source intermittently every 30s to grow a stress relief layer with a thickness of 200nm on the N-type GaN layer.

[0060] S6: Set the reaction chamber pressure to 500 mbar and temperature to 800℃. Introduce 40,000 sccm of NH3, 15,000 sccm of H2, 40,000 sccm of N2, and 25 sccm of TMGa source to grow a periodic InGaN / GaN multi-quantum-well active region layer on the stress-relief layer. The number of InGaN / GaN periods is 10. The thickness of the multi-quantum-well active region layer is 0.15 μm, and the In doping concentration is 1E+20 atom / cm. 3 During the growth of IngaN / GaN, a TMIN source of 1200 sccm was also introduced into the IngaN layer.

[0061] S7: Set the reaction chamber pressure to 300 mbar and temperature to 700 °C, and introduce 55000 sccm of NH3 and 25 sccm of TMGa source to form a low-temperature P-type GaN layer with a thickness of 60 Nm on the multi-quantum well active region layer.

[0062] S8: Set the reaction chamber pressure to 300 mbar and temperature to 800℃, and introduce 55000 sccm of NH3, 600 sccm of CP2Mg source and 120 sccm of TMGa source. At the same time, perform segmented doping to grow a current blocking layer on the low-temperature P-type GaN layer.

[0063] The segmented doping process involves introducing TMIN and TMAl sources of different concentrations in three stages.

[0064] The first stage involves introducing a TMIN source at 250 sccm and a TMA1 source at 70 sccm simultaneously for 60 seconds.

[0065] The second stage involves introducing a 250 sccm TMIN source and simultaneously introducing a 30 sccm TMA1 source for 180 seconds.

[0066] The third stage involves introducing a TMIN source at 800 sccm and shutting off the TMA1 source; this process lasts 60 seconds.

[0067] S9: Finally, the reaction chamber temperature is raised to 900℃ and the pressure to 1000mbar. A 60000sccm source of NH3, a 25sccm source of TMGa, and a 2000sccm source of CP2Mg are introduced to form a 60nm thick high-temperature P-type GaN layer on the current blocking layer. The Mg doping concentration in the high-temperature P-type GaN layer is 1E+20atom / cm³. 3 .

[0068] S10: Lower the temperature of the reaction chamber and perform annealing in a N2 atmosphere at a temperature of 650℃ for 15 minutes. Then lower the temperature to room temperature to complete the epitaxial growth.

[0069] Embodiment four of the present invention is: a method for growing a GaN-based epitaxial structure, comprising the following steps:

[0070] S1: Using a sapphire substrate, the substrate is placed in the reaction chamber of a metal-organic chemical vapor deposition (MOCVD) device. The pressure in the reaction chamber is 600 mbar and the temperature is 1000 °C. H2 is used as the carrier gas for substrate surface treatment. The duration of this process is 12 min.

[0071] S2: Reduce the pressure in the reaction chamber to 200 mbar and the temperature to 800 °C. Using H2 and NH3 as carriers, introduce a 120 sccm TMGa source and a 100 sccm TMAl source, while simultaneously introducing a TMIN source. This process lasts for 6 minutes, during which a buffer layer with a thickness of 0.2 μm is grown on the substrate.

[0072] S3: Raise the temperature to 1150℃, adjust the pressure in the reaction chamber to 120mbar, and introduce a 1200sccm TMGa source. This process lasts for 9 minutes, forming a U-shaped GaN layer with a thickness of 4μm on the buffer layer.

[0073] S4: Increase the pressure in the reaction chamber to 1000 mbar, set the temperature to 1100℃, and introduce 50000 sccm of NH3, 15000 sccm of H2, 50000 sccm of N2 and 1000 sccm of TMGa source to grow an N-type GaN layer with a thickness of 3 μm on the U-type GaN layer.

[0074] S5: Set the reaction chamber temperature to 850℃ and the pressure to 150mbar. Introduce 75000sccm of NH3, 20000sccm of H2 and 80000sccm of N2. Introduce 1500sccm of TEGa source. Introduce 500sccm of TMIN source intermittently every 1 minute to grow a stress relief layer with a thickness of 200nm on the N-type GaN layer.

[0075] S6: Set the reaction chamber pressure to 1000 mbar and temperature to 700℃. Introduce 40000 sccm of NH3, 15000 sccm of H2, 40000 sccm of N2, and 40 sccm of TMGa source to grow a periodic InGaN / GaN multi-quantum-well active region layer on the stress-relief layer. The InGaN / GaN period number is 16. The thickness of the multi-quantum-well active region layer is 0.2 μm, and the InGaN doping concentration is 12E+20 atom / cm. 3 During the growth of IngaN / GaN, a TMIN source of 1500 sccm was also introduced into the IngaN layer.

[0076] S7: Set the reaction chamber pressure to 800 mbar and temperature to 600 °C, and introduce 65000 sccm of NH3 and 50 sccm of TMGa source to form a low-temperature P-type GaN layer with a thickness of 90 Nm on the multi-quantum well active region layer.

[0077] S8: Set the reaction chamber pressure to 800 mbar and temperature to 7000℃, and introduce 65000 sccm of NH3, 700 sccm of CP2Mg source and 150 sccm of TMGa source. At the same time, perform segmented doping to grow a current blocking layer on the low-temperature P-type GaN layer.

[0078] The segmented doping process involves introducing TMIN and TMAl sources of different concentrations in three stages.

[0079] The first stage involves introducing a TMIN source at 350 sccm and simultaneously introducing a TMA1 source at 80 sccm for 90 seconds.

[0080] The second stage involves introducing a TMIN source at 350 sccm and a TMA1 source at 40 sccm simultaneously for 240 seconds.

[0081] The third stage involves introducing a TMIN source at 1000 sccm and shutting off the TMA1 source; this process lasts 80 seconds.

[0082] S9: Finally, the reaction chamber temperature is raised to 1050℃ and the pressure to 600mbar. A 75000sccm source of NH3, a 0sccm source of TMGa, and a 3000sccm source of CP2Mg are introduced to form a 90nm thick high-temperature P-type GaN layer on the current blocking layer. The Mg doping concentration in the high-temperature P-type GaN layer is 1E+20atom / cm³. 3 .

[0083] S10: Lower the temperature of the reaction chamber and perform annealing in a N2 atmosphere at a temperature of 850℃ for 5 minutes. Then lower the temperature to room temperature to complete the epitaxial growth.

[0084] Comparative Example 1 of the present invention is:

[0085] The only difference between Comparative Example 1 and Example 2 is that step S8 is omitted and a current blocking layer is not present.

[0086] Comparative Example 2 of the present invention is: a method for growing an epitaxial wafer containing a conventional current blocking layer.

[0087] The only difference between Comparative Example 2 and Example 2 is in S8: the reaction chamber pressure is set to 300 mbar and the temperature to 900 °C. The CP2Mg source is turned off, and 40,000 sccm of NH3, 15,000 sccm of H2, 40,000 sccm of N2, 100 sccm of TMAl source and 1,000 sccm of TEGa source are introduced for 6 minutes to grow a current blocking layer on the low-temperature P-type GaN layer.

[0088] The epitaxial wafers grown in Example 2, Comparative Example 1, and Comparative Example 2 were fabricated into chips, and electrical tests were performed on the chips. The test results are shown in Table 1 (the data in Table 1 are the average values ​​of multiple chips); the voltage comparison results between Example 2 and Comparative Example 1 are shown in Table 1. Figure 2 The brightness comparison results are shown in [link to relevant documentation]. Figure 3 .

[0089] Note: Figure 2 and Figure 3 The embodiment described is Example 2, and the comparative example is Comparative Example 1; Figure 2 The horizontal axis represents the number of experimental pieces, and the vertical axis represents the number of pieces. Figure 2 Represents voltage (V); Figure 3 The horizontal axis represents the number of films used in the experiment, and the vertical axis represents the brightness (in MW).

[0090] Table 1

[0091]

[0092] Depend on Figures 2-3 As shown in Table 1, under the condition of equivalent electrical properties, the brightness of Example 2 is significantly improved compared to Comparative Example 1 and also improved compared to Comparative Example 2. Adding a segmented doped current blocking layer with gradually varying concentration to low-temperature P-type GaN can restrict the charge carriers and reduce electron transitions without affecting the various electrical properties of the epitaxial wafer, thus significantly improving the luminous efficiency.

[0093] In summary, the GaN-based epitaxial structure provided by this invention, through a stepped TMIN / TMAl process, incorporates a segmented doped current-blocking layer with gradually varying concentrations into low-temperature P-type GaN. The current-blocking layer undergoes three stages of TMIN and TMAl source introduction with specific combinations, optimizing the Al and IN composition to form segmented doped current-blocking layers with varying concentrations. This segmented doped current-blocking layer not only ionizes more holes, increasing the hole concentration in the quantum well and better matching it with the electron concentration, allowing high-energy blocked electrons to directly enter the P-type structure, thus effectively suppressing current overflow and reducing electron transitions while maintaining electrical properties, thereby improving brightness and luminous efficiency; it also suppresses dislocation propagation in the quantum well, confining electrons to a fixed region, thus improving the quality of the epitaxial wafer.

[0094] 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 method of growing a GaN-based epitaxial structure, characterized by, The preparation of the current blocking layer comprises three stages: The first stage: simultaneously input 250-350 sccm of the TMIN source and 70-80 sccm of the TMAl source, and the input time of the TMIN source and the TMAl source is equal; The second stage: simultaneously input 250-350 sccm of the TMIN source and 30-40 sccm of the TMAl source, and the input time of the TMIN source and the TMAl source is equal; The third stage: input 800-1000 sccm of the TMIN source, and close the TMAl source. The GaN-based epitaxial structure comprises, in sequence, an AlN layer, a buffer layer, a U-shaped GaN layer, an N-type GaN layer, a stress release layer and a multi-quantum-step active region layer grown on a substrate. The multi-quantum-step active region layer has, in sequence, a low-temperature P-type GaN layer, a current blocking layer and a high-temperature P-type GaN layer grown thereon.

2. The method of growing a GaN-based epitaxial structure according to claim 1, wherein The duration of the first stage is 60-90 s, the duration of the second stage is 180-240 s, and the duration of the third stage is 60-80 s.

3. The method of growing a GaN-based epitaxial structure according to claim 1, wherein The growth of the current blocking layer is performed in a reaction chamber, and the temperature of the reaction chamber is set to 700-800 DEG C, and the pressure is set to 300-800 mbar.

4. The method of growing a GaN-based epitaxial structure according to claim 3, wherein During the growth of the current blocking layer, 55,000-65,000 sccm of NH3, 600-700 sccm of CP2Mg and 120-150 sccm of TMGa source are continuously input into the reaction chamber.

5. The method of growing a GaN-based epitaxial structure according to claim 1, wherein The multi-quantum-step active region layer comprises 10-16 periods of INGaN layers and GaN layers stacked in sequence.

6. The method of growing a GaN-based epitaxial structure according to claim 5, wherein During the growth of the INGaN layer, 1,200-1,500 sccm of the TMIN source and 25-40 sccm of the TMGa source are input; During the growth of the GaN layer, the TMIN source is closed, and 25-40 sccm of the TMGa source is input.

7. The method of growing a GaN-based epitaxial structure of claim 1, wherein, The growth of the multi-quantum-step active region layer is performed in a reaction chamber, and the temperature of the reaction chamber is set to 700-800 DEG C, and the pressure is set to 500-1,000 mbar.

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