Boron nitride van der waals epitaxial gallium nitride microwave material and growth method

Abstract

The application discloses a boron nitride van der Waals epitaxial gallium nitride microwave material and a growth method. An ammonia-rich aluminum nitride nucleation layer is introduced on the surface of a boron nitride two-dimensional material, thereby providing high-density nucleation sites for the growth of a subsequent gallium nitride transition layer. The aluminum nitride nucleation layer is subjected to annealing treatment to block grain boundary dislocations. A gallium nitride transition layer with low temperature and high V / III ratio is introduced to promote a lateral epitaxial mode in the initial growth of the gallium nitride, thereby accelerating the turning and blocking of threading dislocations. The growth process of a gallium nitride buffer layer is high-temperature and low-V / III-ratio, thereby promoting the gallium nitride buffer layer to be in a layered epitaxial mode, improving the material surface morphology and crystal quality. A gallium nitride channel layer with high temperature and high V / III ratio is introduced to improve the electron transport characteristics. The technical scheme is based on a material growth method such as MOCVD, and the material is developed through one-time epitaxy technology. Through epitaxy technology improvement and process control, the material with high surface flatness, crystal quality and electron transport characteristics is developed.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor epitaxial materials technology, and specifically relates to a boron nitride van der Waals epitaxial gallium nitride microwave material and its growth method. Background Technology

[0002] Gallium nitride (GaN) high electron mobility field-effect transistors (HFETs) possess advantages such as high output power density, high operating frequency, and radiation resistance, making them significantly advantageous in microwave power device applications. They are rapidly developing towards higher power levels, with S-band output power reaching kilowatt levels and power density reaching 20 W / mm². However, limited by the device's internal heat transfer capabilities, a large amount of heat generated near the junction in RF mode cannot be fully released, preventing the intrinsic high power advantage of GaN microwave power devices from being fully realized. Some studies suggest that transferring GaN microwave power devices to diamond substrates with higher thermal conductivity through heterogeneous integration can increase power density by more than four times. However, heterogeneous integration processes are complex, and the interface between the epitaxial layer and the diamond substrate is prone to contamination, introducing uncertainties to device reliability. Furthermore, a significant factor limiting the widespread application of GaN microwave power devices is their high cost, with the high price of single-crystal substrates being a major reason for the persistently high cost of GaN microwave power devices.

[0003] Recent research has shown that gallium nitride (GaN) microwave materials fabricated using techniques such as remote epitaxy or van der Waals epitaxy can be completely separated from the growth substrate through a relatively simple mechanical peeling process. These materials can then be transferred to other substrates that are not subject to lattice or thermal matching, such as diamond or metal substrates, resulting in a significant increase in output power density. Transferring to flexible substrates expands application scenarios, and the growth substrate can be reused, significantly reducing the manufacturing cost of GaN microwave power devices. However, conventional remote epitaxy or van der Waals epitaxy techniques do not involve a single epitaxy of the two-dimensional material and the GaN microwave material. Instead, the GaN microwave material is grown through a secondary epitaxy after the two-dimensional material has been grown. This is not conducive to large-scale mass production, and the secondary epitaxy process easily introduces impurities and crystal defects, affecting the performance of GaN microwave power devices. Furthermore, the atomic layers of two-dimensional materials such as graphene and boron nitride are dominated by van der Waals forces, and there are no dangling bonds on the material surface. This makes it impossible to provide high-density nucleation sites for nitride materials such as gallium nitride and aluminum nitride, resulting in rough surfaces and low crystal quality of the subsequently grown nitride materials, which is insufficient to meet the development requirements of high-performance gallium nitride microwave power devices.

[0004] Therefore, based on material growth methods such as MOCVD, the use of one-step epitaxy technology to achieve remote epitaxy of two-dimensional materials or van der Waals epitaxy of gallium nitride microwave materials, and the significant improvement in the quality of gallium nitride microwave materials through epitaxial technology improvement and process control, is of great significance for the widespread application of gallium nitride microwave devices in high-power, flexible, and low-cost fields.

[0005] A prior art method for growing boron nitride van der Waals epitaxial gallium nitride microwave materials includes the following steps:

[0006] Step (1): Select a 2-inch sapphire single crystal substrate and place it on the base inside the MOCVD equipment;

[0007] Step (2): Set the reaction chamber pressure to 80 torr, introduce H2 at a flow rate of 100 slm, heat the system to 1070℃, bake the substrate for 10 minutes, and remove contaminants from the substrate surface;

[0008] Step (3): Set the reaction chamber pressure to 50 torr and the temperature to 1100℃ in an atmosphere with an H2 flow rate of 120 slm. Introduce 8 slm of NH3 and maintain it for 5 minutes to perform nitriding treatment on the substrate surface.

[0009] Step (4): Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the organometallic source triethylboron, and adjust the flow rate of NH3 and triethylboron to make the molar ratio of NH3 and triethylboron reach 2800, grow a 1.7nm thick two-dimensional boron nitride material, and turn off triethylboron.

[0010] Step (5): Set the reaction chamber pressure to 70 torr and the temperature to 810℃ under NH3 atmosphere, introduce the organometallic source trimethylaluminum, and adjust the flow rates of NH3 and trimethylaluminum to make the molar ratio of NH3 and trimethylaluminum reach 800, grow an aluminum nitride nucleation layer with a thickness of 35nm, and turn off trimethylaluminum.

[0011] Step (6): Set the reaction chamber pressure to 300 torr and the temperature to 1080℃ in an NH3 atmosphere. Introduce the metal-organic source trimethylgallium and adjust the flow rates of NH3 and trimethylgallium to achieve a molar ratio of 1700 between NH3 and trimethylgallium. Grow a 2000nm thick gallium nitride buffer layer and turn off trimethylgallium.

[0012] Step (7): Set the reaction chamber pressure to 70 torr and the temperature to 1050℃ under an NH3 atmosphere, and introduce the organometallic sources trimethylgallium and trimethylaluminum to grow a 20nm thick aluminum gallium nitride (Al) layer. 0.3 Ga 0.7 N-barrier layer, shutting off trimethylgallium and trimethylaluminum;

[0013] Step (8): Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce trimethylgallium, grow a 2nm thick gallium nitride cap layer, and then turn off trimethylgallium;

[0014] Step (9): Under NH3 atmosphere protection, the material is cooled to room temperature and the epitaxial material is removed. Summary of the Invention

[0015] The purpose of this invention is to provide a boron nitride van der Waals epitaxial gallium nitride microwave material and its growth method. Based on material growth methods such as MOCVD, the boron nitride van der Waals epitaxial gallium nitride microwave material is developed through a single epitaxial process. Furthermore, through improvements in epitaxial technology and process control, the material with high surface flatness, crystal quality, and electronic transport properties is developed.

[0016] To achieve the above objectives, the solution of the present invention is:

[0017] A method for growing gallium nitride microwave material via boron nitride van der Waals epitaxy includes the following steps:

[0018] Step 1: Select a substrate and place it on the base inside the MOCVD equipment;

[0019] Step 2: Set the reaction chamber pressure to 50-100 torr, introduce hydrogen gas, raise the temperature to 1000-1100℃, and bake the substrate for 5-15 minutes;

[0020] Step 3: Set the reaction chamber pressure to 30-150 torr and the temperature to 950-1250℃ under a hydrogen atmosphere, introduce ammonia gas and maintain it for 1-20 minutes;

[0021] Step 4: Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the organometallic boron source, and adjust the flow rates of ammonia and boron source to make the molar ratio of ammonia to boron source reach 1500 to 6000 to grow 1 to 3 nm thick two-dimensional boron nitride material, and then turn off the boron source.

[0022] Step 5: Set the reaction chamber pressure to 30-200 torr under an ammonia atmosphere, lower the temperature to 700-950°C, introduce a metal-organic aluminum source, and adjust the flow rates of ammonia and aluminum source to achieve a molar ratio of N1 to grow an aluminum nitride nucleation layer with a thickness of T, then turn off the aluminum source.

[0023] Step 6: Set the reaction chamber pressure to 100-500 torr under an ammonia atmosphere, raise the temperature to T1, and perform an annealing treatment on the aluminum nitride nucleation layer for a duration of t.

[0024] Step 7: Keep the reaction chamber pressure, temperature T1 and gas flow rate constant, introduce the metal-organic gallium source, and adjust the flow rates of ammonia and gallium source to achieve the molar ratio of ammonia to gallium source to N2, grow a 50-500 nm thick gallium nitride transition layer, and then turn off the gallium source.

[0025] Step 8: Set the reaction chamber pressure to 100-500 torr under an ammonia atmosphere, raise the temperature to T2, introduce a metal-organic gallium source, and adjust the flow rates of ammonia and gallium source to achieve a molar ratio of ammonia to gallium source of N3, grow a 300-3000 nm thick gallium nitride buffer layer, and then turn off the gallium source.

[0026] Step 9: Keep the reaction chamber pressure, temperature T2 and gas flow rate constant, introduce the metal-organic gallium source, and adjust the flow rates of ammonia and gallium source to achieve the molar ratio of ammonia to gallium source to N4, grow a 50-500 nm thick gallium nitride channel layer, and then turn off the gallium source.

[0027] Step 10: Under an ammonia atmosphere, set the reaction chamber pressure to 30–150 torr and the temperature to 950–1100°C, then introduce a metal-organic gallium source and an aluminum source to grow aluminum gallium nitride (Al). x Ga 1-x An N-barrier layer, in which the aluminum composition is 0 < x ≤ 1, shuts off the gallium source and the aluminum source;

[0028] Step 11: Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the gallium source, grow the gallium nitride cap layer, and then turn off the gallium source;

[0029] Step 12: Under the protection of an ammonia atmosphere, allow the temperature to drop to room temperature and remove the epitaxial material.

[0030] The boron nitride two-dimensional material in step 4, the aluminum nitride nucleation layer in step 5, the gallium nitride transition layer in step 7, the gallium nitride buffer layer in step 8, the gallium nitride channel layer in step 9, the aluminum gallium nitride barrier layer in step 10, and the gallium nitride cap layer in step 11 are all grown in a single epitaxial furnace using a single epitaxial process.

[0031] In step 5 above, the molar ratio N1 of ammonia and aluminum source ranges from 1200 to 6000, and the growth thickness T ranges from 8 to 30 nm.

[0032] In step 6 above, the annealing temperature T1 ranges from 950 to 1050°C, and the annealing time t ranges from 2 to 10 minutes.

[0033] In step 7 above, the molar ratio N2 of ammonia and gallium source is in the range of 2500 to 6000.

[0034] In step 8 above, the growth temperature T2 of the gallium nitride buffer layer is in the range of 1050 to 1200°C, and the molar ratio N3 of ammonia and gallium source is in the range of 600 to 2500.

[0035] In step 9 above, the molar ratio N4 of ammonia and gallium source is in the range of 2500 to 6000.

[0036] A boron nitride van der Waals epitaxial gallium nitride microwave material, fabricated based on the aforementioned boron nitride van der Waals epitaxial gallium nitride microwave material growth method, comprises, in the following order from bottom to top: a substrate, a two-dimensional boron nitride material, an aluminum nitride nucleation layer, a gallium nitride transition layer, a gallium nitride buffer layer, a gallium nitride channel layer, and an aluminum gallium nitride (Al) layer. x Ga 1-x N-barrier layer, gallium nitride cap layer.

[0037] The beneficial effects of this invention, achieved by adopting the above scheme, are as follows: Ammonia-rich thin aluminum nitride nucleation layer is introduced onto the surface of the boron nitride two-dimensional material, providing a high-density nucleation grid for the subsequent growth of the gallium nitride transition layer; the aluminum nitride nucleation layer is annealed to block grain boundary dislocations; a low-temperature, high V / III ratio gallium nitride transition layer is introduced, promoting lateral epitaxy in the early stages of gallium nitride growth, accelerating the redirection and blocking of penetrating dislocations; the gallium nitride buffer layer is grown at a high temperature and low V / III ratio, promoting layered epitaxy and improving the material surface morphology and crystal quality; a high-temperature, high V / III ratio gallium nitride channel layer is introduced to enhance electron transport characteristics. This method can achieve boron nitride van der Waals epitaxial gallium nitride microwave materials with smooth surface, high crystal quality, and high electron transport characteristics. Furthermore, the complete material growth is achieved through a single epitaxial process, avoiding the introduction of impurities and defects, and promoting the application of gallium nitride microwave devices in flexible, high-power, and low-cost fields.

[0038] The invention can use a sapphire single crystal substrate, and is also applicable to silicon carbide, gallium nitride, silicon and other semi-insulating substrates suitable for epitaxial growth of group V / III nitrides. Attached Figure Description

[0039] Figure 1 This is a comparison of the gallium nitride (002) surface rocking curves of gallium nitride microwave materials prepared by conventional processes and the embodiments of the present invention;

[0040] Figure 2 This is a comparison of the gallium nitride (102) surface rocking curves of gallium nitride microwave materials prepared by conventional processes and the embodiments of the present invention;

[0041] Figure 3 (a) and 3(b) are the surface morphologies of the boron nitride van der Waals epitaxial gallium nitride microwave materials prepared by the embodiments of the present invention and by conventional processes, respectively (tested by atomic force microscopy, test range is 5μm×5μm);

[0042] Figure 4This is a schematic diagram of the structure of the boron nitride van der Waals epitaxial gallium nitride microwave material prepared by this invention. Detailed Implementation

[0043] The technical solution and beneficial effects of the present invention will be described in detail below with reference to the accompanying drawings.

[0044] Cooperate Figure 4 As shown, the present invention provides a method for growing boron nitride van der Waals epitaxial gallium nitride microwave material in an MOCVD system, comprising the following steps:

[0045] Step 1: Select a single crystal substrate 1 and place it on the base inside the equipment for material growth such as metal-organic chemical vapor deposition (MOCVD);

[0046] Step 2: Set the reaction chamber pressure to 50-100 torr, introduce hydrogen gas (H2), raise the temperature to 1000-1100℃, bake the substrate for 5-15 minutes, and remove contaminants from the substrate surface;

[0047] Step 3: Set the reaction chamber pressure to 30-150 torr and the temperature to 950-1250℃ in an H2 atmosphere, introduce ammonia (NH3) and maintain for 1-20 minutes to perform nitriding treatment on the substrate surface;

[0048] Step 4: Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the organometallic boron source, and adjust the flow rates of NH3 and boron source to make the molar ratio of NH3 and boron source reach 1500 to 6000 to grow a 1 to 3 nm thick two-dimensional boron nitride material 2, and then turn off the boron source.

[0049] Step 5: Set the reaction chamber pressure to 30-200 torr under an NH3 atmosphere, lower the temperature to 700-950℃, introduce a metal-organic aluminum source, and adjust the flow rates of NH3 and aluminum source to achieve a molar ratio of N1 to grow an aluminum nitride nucleation layer 3 with a thickness of T, and then turn off the aluminum source.

[0050] Step 6: Set the reaction chamber pressure to 100-500 torr under an NH3 atmosphere, raise the temperature to T1, and perform an annealing treatment on the aluminum nitride nucleation layer for a duration of t.

[0051] Step 7: Keep the reaction chamber pressure, temperature T1 and gas flow rate constant, introduce the metal-organic gallium source, and adjust the flow rates of NH3 and gallium source to achieve the molar ratio of NH3 and gallium source to N2, grow a 50-500 nm thick gallium nitride transition layer 4a, and then turn off the gallium source.

[0052] Step 8: Set the reaction chamber pressure to 100-500 torr under an NH3 atmosphere, raise the temperature to T2, introduce a metal-organic gallium source, and adjust the flow rates of NH3 and gallium source to achieve a molar ratio of NH3 to gallium source of N3, grow a 300-3000 nm thick gallium nitride buffer layer 4b, and then turn off the gallium source.

[0053] Step 9: Keep the reaction chamber pressure, temperature T2 and gas flow rate constant, introduce the metal-organic gallium source, and adjust the flow rates of NH3 and gallium source to make the molar ratio of NH3 and gallium source reach N4, grow a 50-500 nm thick gallium nitride channel layer 4c, and then turn off the gallium source.

[0054] Step 10: Under an NH3 atmosphere, set the reaction chamber pressure to 30–150 torr and the temperature to 950–1100°C, then introduce a metal-organic gallium source and an aluminum source to grow aluminum gallium nitride (Al). x Ga 1-x N-barrier layer 5, where the aluminum composition is 0 < x ≤ 1, shutting off the gallium source and aluminum source;

[0055] Step 11: Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the gallium source, grow the gallium nitride cap layer 6, and then turn off the gallium source;

[0056] Step 12: Under NH3 atmosphere protection, allow the temperature to drop to room temperature and remove the epitaxial material.

[0057] The boron nitride two-dimensional material 2 in step 4, the aluminum nitride nucleation layer 3 in step 5, the gallium nitride transition layer 4a in step 7, the gallium nitride buffer layer 4b in step 8, the gallium nitride channel layer 4c in step 9, the aluminum gallium nitride barrier layer 5 in step 10, and the gallium nitride cap layer 6 in step 11 are all grown in a single epitaxial furnace using a single epitaxial process. This reduces the introduction of impurities and defects, which is beneficial for improving the quality of boron nitride van der Waals epitaxial gallium nitride microwave materials and device performance.

[0058] In step 5, the ammonia-rich, thin-layer aluminum nitride nucleation layer 3 has an NH3 to aluminum source molar ratio N1 ranging from 1200 to 6000, and a thickness T ranging from 8 to 30 nm. If the molar ratio is too low (N1 < 1200), the aluminum nitride nucleation islands will be large, failing to provide a high-density nucleation grid for the subsequent gallium nitride transition layer, resulting in a rough material surface and poor crystal quality. If the molar ratio is too high (N1 > 6000), the surface migration rate of aluminum atoms will decrease, leading to poor crystal quality of the aluminum nitride nucleation layer, which is also detrimental to the subsequent growth of high-quality gallium nitride materials. If the aluminum nitride nucleation layer thickness is too small (T < 8 nm), the crystal orientation of the aluminum nitride nucleation layer will be disordered, making it impossible to achieve the two-dimensional layered growth of the subsequent gallium nitride material. If the aluminum nitride nucleation layer thickness is too large (T > 30 nm), the residual stress during the epitaxial growth of the gallium nitride material will be high, causing the gallium nitride to wrinkle and detach from the substrate surface. Therefore, the N1 range was finally determined to be 1200–6000, and its thickness T ranged from 8 to 30 nm.

[0059] In step 6, the annealing treatment of the aluminum nitride nucleation layer 3 has an annealing temperature T1 ranging from 950 to 1050°C and a duration t ranging from 2 to 10 minutes. The aluminum nitride nucleation layer is subjected to an annealing treatment at a temperature higher than its growth temperature for a certain period of time, which causes recrystallization on its surface, weakens the grain boundary characteristics of aluminum nitride, and has a blocking effect on grain boundary dislocations, thus providing a good template for the subsequent growth of gallium nitride materials.

[0060] The low-temperature, high V / III ratio gallium nitride transition layer 4a in step 7 has the same growth temperature as T1, and the molar ratio N2 of NH3 and gallium source is in the range of 2500 to 6000. Introducing the low-temperature, high V / III ratio gallium nitride transition layer can promote the lateral epitaxial mode in the early stage of gallium nitride growth, accelerate the redirection and blocking of penetrating dislocations, and help improve the crystal quality of the subsequent gallium nitride buffer layer and the electronic transport characteristics of the heterojunction.

[0061] The high-temperature, low V / III ratio gallium nitride buffer layer 4b in step 8 has a growth temperature T2 ranging from 1050 to 1200°C, and a molar ratio N3 of NH3 to gallium source ranging from 600 to 2500. The high-temperature, low V / III ratio process promotes a rapid transition of gallium nitride growth from lateral epitaxy to layered epitaxy, improving the surface morphology of the material. At the same time, it enhances the surface migration rate of gallium atoms and improves the crystal quality of the gallium nitride buffer layer.

[0062] The high-temperature, high V / III ratio gallium nitride channel layer 4c in step 9 has the same growth temperature as T2, and its molar ratio N4 of NH3 and gallium source is in the range of 2500 to 6000. The high-temperature, high V / III ratio process provides an ammonia-rich atmosphere, which can suppress the formation of point defects such as nitrogen vacancies or carbon-substituted nitrogen atoms in the gallium nitride channel layer, and is beneficial to improving the electronic transport characteristics of the heterojunction.

[0063] This invention also provides a boron nitride van der Waals epitaxial gallium nitride microwave material, fabricated based on the above-described growth method for boron nitride van der Waals epitaxial gallium nitride microwave material, comprising, in the following order from bottom to top: a single-crystal substrate 1, a boron nitride two-dimensional material 2, an aluminum nitride nucleation layer 3, a gallium nitride transition layer 4a, a gallium nitride buffer layer 4b, a gallium nitride channel layer 4c, and an aluminum gallium nitride (Al) layer. x Ga 1-x N-barrier layer 5, gallium nitride cap layer 6, can be referenced. Figure 4 As shown.

[0064] Example:

[0065] Step (1): Select a 2-inch sapphire single crystal substrate and place it on the base inside the equipment for material growth such as metal-organic chemical vapor deposition (MOCVD);

[0066] Step (2): Set the reaction chamber pressure to 80 torr, introduce H2 at a flow rate of 100 slm, heat the system to 1070℃, bake the substrate for 10 minutes, and remove contaminants from the substrate surface;

[0067] Step (3): Set the reaction chamber pressure to 50 torr and the temperature to 1100℃ in an atmosphere with an H2 flow rate of 120 slm. Introduce 8 slm of NH3 and maintain it for 5 minutes to perform nitriding treatment on the substrate surface.

[0068] Step (4): Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the organometallic source triethylboron, and adjust the flow rate of NH3 and triethylboron to make the molar ratio of NH3 and triethylboron reach 2800, grow a 1.7nm thick two-dimensional boron nitride material, and turn off triethylboron.

[0069] Step (5): Set the reaction chamber pressure to 70 torr under NH3 atmosphere, lower the temperature to 810℃, introduce the organometallic source trimethylaluminum, and adjust the flow rates of NH3 and trimethylaluminum to make the molar ratio of NH3 and trimethylaluminum reach 3200, grow an aluminum nitride nucleation layer with a thickness of 18nm, and turn off trimethylaluminum.

[0070] Step (6): Set the reaction chamber pressure to 200 torr and the temperature to 1000℃ under an NH3 atmosphere, and perform an annealing treatment on the aluminum nitride nucleation layer for 4 minutes.

[0071] Step (7): Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the metal-organic source trimethylgallium, and adjust the flow rates of NH3 and trimethylgallium to make the molar ratio of NH3 and trimethylgallium reach 3800, grow a 300nm thick gallium nitride transition layer, and turn off trimethylgallium.

[0072] Step (8): Set the reaction chamber pressure to 300 torr under NH3 atmosphere, raise the temperature to 1080℃, introduce the metal-organic source trimethylgallium, and adjust the flow rates of NH3 and trimethylgallium to make the molar ratio of NH3 and trimethylgallium reach 1700, grow a 1500nm thick gallium nitride buffer layer, and turn off trimethylgallium.

[0073] Step (9): Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the metal-organic source trimethylgallium, and adjust the flow rates of NH3 and trimethylgallium to make the molar ratio of NH3 and trimethylgallium reach 4000, grow a 200nm thick gallium nitride channel layer, and turn off trimethylgallium.

[0074] Step (10): Set the reaction chamber pressure to 70 torr and the temperature to 1050℃ under an NH3 atmosphere, and introduce the organometallic sources trimethylgallium and trimethylaluminum to grow a 20nm thick aluminum gallium nitride (Al) layer. 0.3 Ga 0.7 N-barrier layer, shutting off trimethylgallium and trimethylaluminum;

[0075] Step (11): Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce trimethylgallium, grow a 2nm thick gallium nitride cap layer, and then turn off trimethylgallium;

[0076] Step (12): Under the protection of NH3 atmosphere, the epitaxial material is removed when the temperature drops to room temperature.

[0077] like Figure 1 and Figure 2 As shown, compared with conventional processes, the boron nitride van der Waals epitaxial gallium nitride microwave material prepared by introducing an ammonia-rich thin aluminum nitride nucleation layer, annealing the aluminum nitride nucleation layer, introducing a low-temperature high V / III ratio gallium nitride transition layer and a high-temperature high V / III ratio gallium nitride channel layer in this embodiment of the invention has a half-width at half-maximum (WHM) of gallium nitride (002) plane and (102) plane that are reduced from 0.34° to 0.21° and from 0.63° to 0.38°, respectively, indicating that the crystal quality of the material has been significantly improved.

[0078] like Figure 3 As shown in (a) and (b), compared with conventional processes, the boron nitride van der Waals epitaxial gallium nitride microwave material prepared by introducing an ammonia-rich thin aluminum nitride nucleation layer, annealing the aluminum nitride nucleation layer, introducing a low-temperature high V / III ratio gallium nitride transition layer, and a high-temperature high V / III ratio gallium nitride channel layer in the embodiments of the present invention has a surface roughness (rms) of 5μm×5μm that is reduced from 1.013nm to 0.264nm, indicating that the surface smoothness of the material is significantly improved.

[0079] Compared with conventional processes, the boron nitride van der Waals epitaxial gallium nitride microwave material prepared in this embodiment of the invention introduces an ammonia-rich thin-layer aluminum nitride nucleation layer, anneals the aluminum nitride nucleation layer, introduces a low-temperature high V / III ratio gallium nitride transition layer, and a high-temperature high V / III ratio gallium nitride channel layer. The electron mobility at room temperature is increased from 1417 cm⁻¹. 2 / Vs increased to 1833cm 2 / Vs indicates that the electron transport properties have been significantly improved.

[0080] The boron nitride van der Waals epitaxial gallium nitride microwave material prepared by introducing an ammonia-rich thin aluminum nitride nucleation layer, annealing the aluminum nitride nucleation layer, introducing a low-temperature high V / III ratio gallium nitride transition layer, and a high-temperature high V / III ratio gallium nitride channel layer in the embodiments provided by the present invention has significantly improved crystal quality, surface flatness, and electron transport characteristics, promoting the application of gallium nitride microwave devices in fields such as flexibility, high power, and low cost.

[0081] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for growing gallium nitride microwave materials via boron nitride van der Waals epitaxy, characterized in that... Includes the following steps: Step 1: Select a substrate and place it on the base inside the MOCVD equipment; Step 2: Set the reaction chamber pressure to 50-100 torr, introduce hydrogen gas, raise the temperature to 1000-1100℃, and bake the substrate for 5-15 minutes; Step 3: Set the reaction chamber pressure to 30-150 torr and the temperature to 950-1250℃ under a hydrogen atmosphere, introduce ammonia gas and maintain it for 1-20 minutes; Step 4: Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the organometallic boron source, and adjust the flow rates of ammonia and boron source to make the molar ratio of ammonia to boron source reach 1500 to 6000 to grow 1 to 3 nm thick two-dimensional boron nitride material, and then turn off the boron source. Step 5: Set the reaction chamber pressure to 30-200 torr under an ammonia atmosphere, lower the temperature to 700-950°C, introduce a metal-organic aluminum source, and adjust the flow rates of ammonia and aluminum source to achieve a molar ratio of N1 to grow an aluminum nitride nucleation layer with a thickness of T, then turn off the aluminum source. Step 6: Set the reaction chamber pressure to 100-500 torr under an ammonia atmosphere, raise the temperature to T1, and perform an annealing treatment on the aluminum nitride nucleation layer for a duration of t. Step 7: Keep the reaction chamber pressure, temperature T1 and gas flow rate constant, introduce the metal-organic gallium source, and adjust the flow rates of ammonia and gallium source to achieve the molar ratio of ammonia to gallium source to N2, grow a 50-500 nm thick gallium nitride transition layer, and then turn off the gallium source. Step 8: Set the reaction chamber pressure to 100-500 torr under an ammonia atmosphere, raise the temperature to T2, introduce a metal-organic gallium source, and adjust the flow rates of ammonia and gallium source to achieve a molar ratio of ammonia to gallium source of N3, grow a 300-3000 nm thick gallium nitride buffer layer, and then turn off the gallium source. Step 9: Keep the reaction chamber pressure, temperature T2 and gas flow rate constant, introduce the metal-organic gallium source, and adjust the flow rates of ammonia and gallium source to achieve the molar ratio of ammonia to gallium source to N4, grow a 50-500 nm thick gallium nitride channel layer, and then turn off the gallium source. Step 10: Under an ammonia atmosphere, set the reaction chamber pressure to 30–150 torr and the temperature to 950–1100°C, then introduce a metal-organic gallium source and an aluminum source to grow aluminum gallium nitride (Al). x Ga 1-x An N-barrier layer, in which the aluminum composition is 0 < x ≤ 1, shuts off the gallium source and the aluminum source; Step 11: Keep the pressure, temperature and gas flow rate of the reaction chamber constant, introduce the gallium source, grow the gallium nitride cap layer, and then turn off the gallium source; Step 12: Under the protection of an ammonia atmosphere, allow the temperature to drop to room temperature and remove the epitaxial material.

2. The method as described in claim 1, characterized in that: The boron nitride two-dimensional material in step 4, the aluminum nitride nucleation layer in step 5, the gallium nitride transition layer in step 7, the gallium nitride buffer layer in step 8, the gallium nitride channel layer in step 9, the aluminum gallium nitride barrier layer in step 10, and the gallium nitride cap layer in step 11 are all grown in a single epitaxial furnace using a single epitaxial process.

3. The method as described in claim 1, characterized in that: In step 5, the molar ratio N1 of ammonia and aluminum source ranges from 1200 to 6000, and the growth thickness T ranges from 8 to 30 nm.

4. The method as described in claim 1, characterized in that: In step 6, the annealing temperature T1 ranges from 950 to 1050°C, and the annealing time t ranges from 2 to 10 minutes.

5. The method as described in claim 1, characterized in that: In step 7, the molar ratio N2 of ammonia and gallium source is in the range of 2500 to 6000.

6. The method as described in claim 1, characterized in that: In step 8, the growth temperature T2 of the gallium nitride buffer layer is in the range of 1050 to 1200°C, and the molar ratio N3 of ammonia and gallium source is in the range of 600 to 2500.

7. The method as described in claim 1, characterized in that: In step 9, the molar ratio N4 of ammonia and gallium source is in the range of 2500 to 6000.

8. A boron nitride van der Waals epitaxial gallium nitride microwave material, fabricated based on the growth method of the boron nitride van der Waals epitaxial gallium nitride microwave material as described in claim 1, characterized in that: The layers, arranged in ascending order of growth, include: substrate, boron nitride two-dimensional material, aluminum nitride nucleation layer, gallium nitride transition layer, gallium nitride buffer layer, gallium nitride channel layer, and aluminum gallium nitride (Al). x Ga 1-x N-barrier layer, gallium nitride cap layer.

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