A 4H-SiC-GaN heterostructure-based p-i-n type ultraviolet photodetector and a preparation method thereof

Abstract

This invention relates to the field of ultraviolet photodetector fabrication, specifically to a p-i-n type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure and its fabrication method. At the material structure level, this invention significantly reduces dislocation defects, laying a solid foundation for subsequent high-quality crystal growth and ensuring structural stability of the detector under complex operating conditions. It effectively avoids material damage caused by thermal expansion and contraction or lattice stress, greatly improving the reliability and durability of the detector. The fabrication process is meticulously detailed. MOCVD technology is used for growth, with precise control of parameters at each stage. Furthermore, high-purity metal combined with an appropriate evaporation rate and deposition thickness, along with high-vacuum physical vapor deposition technology, ensures good ohmic contact between the metal and semiconductor, resulting in high hole injection efficiency, reduced carrier recombination probability, and effectively improved photoelectric conversion efficiency, demonstrating broad market prospects.

Description

Technical Field

[0001] This invention relates to the field of ultraviolet photodetector fabrication, and more particularly to a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure and its fabrication method. Background Technology

[0002] With the development of science and technology, ultraviolet (UV) detection technology is playing an increasingly important role in many fields. Silicon carbide (SiC), as a prominent representative of third-generation semiconductors, has injected powerful momentum into the field of UV detection due to its unique physical properties. Its high thermal conductivity allows heat generated during operation to dissipate rapidly, preventing device performance degradation due to overheating and ensuring stable operation of the detector in high-temperature environments. For example, in high-temperature monitoring scenarios around aerospace engines, SiC-based detectors exhibit excellent heat resistance. Excellent electron mobility endows carriers with the ability to move rapidly, greatly accelerating signal transmission speed and allowing the detector to respond more responsively to the rapid changes in UV light. Its exceptional hardness ensures the structural integrity of the detector in complex mechanical environments, maintaining normal operation even after a certain degree of impact or compression. Its excellent chemical stability allows it to resist corrosion from acids and alkalis, making it suitable for harsh conditions such as chemical plants and marine environmental monitoring. SiC-based pin-structured UV photodetectors, with their ingenious structural design, are widely used in various fields. The intrinsic (I-type) semiconductor layer embedded between the p-type and n-type semiconductors effectively expands the width of the depletion region, acting like a bridge. This expansion is significant. On the one hand, it enables the detector to collect photogenerated carriers more efficiently, significantly enhancing its sensitivity and making even weak ultraviolet light signals impossible to miss. On the other hand, the wider depletion region accelerates the separation and transmission speed of carriers, greatly improving the detector's response speed and enabling it to capture key information in a timely manner in rapidly changing real-world detection scenarios.

[0003] However, existing technologies still face numerous obstacles in the pursuit of higher performance. Regarding PIN-type ultraviolet detectors made from organic semiconductor thin films, although patent CN118102738A proposes inserting an inorganic intrinsic semiconductor thin film between a P-type and an N-type organic semiconductor thin film to form a PIN structure, seemingly solving some contact problems and providing a solution to the persistent issues of slow response speed and high dark current in organic photodiode detectors, a deeper examination reveals that the inherent limitations of organic semiconductor thin films are difficult to overcome. Their fabrication process is complex and cumbersome, involving the precise synthesis and doping of various high-purity organic materials. Even minor deviations in each step can lead to significant differences in film performance. Furthermore, during long-term operation or storage, organic materials are highly susceptible to external environmental factors, with chemical or physical changes such as oxidation and photodegradation occurring at any time. For example, an organic semiconductor PIN-type ultraviolet detector used for long-term outdoor environmental monitoring showed obvious signs of aging after months of exposure to sun and rain, resulting in a significant decrease in detector responsivity and a sharp increase in dark current, ultimately failing to meet monitoring requirements. This fundamentally limits its large-scale industrial application.

[0004] For example, patent CN117637896A provides a special PIN photodetector that attempts to optimize detector performance by carefully setting P-type doped regions and N-type ohmic contact layers on both sides of the intrinsic layer, and stacking several antireflection films on the photosensitive window of the P-type doped region. Undeniably, antireflection films can theoretically increase light transmittance and improve the detector's ability to capture light signals. However, in practice, the stacking of multiple antireflection films brings a series of thorny problems. The refractive index of each antireflection film needs to be precisely controlled, ensuring that they increase sequentially towards the intrinsic layer, which places extremely high demands on process precision. Achieving this stably and accurately on a large-scale industrial production line is extremely difficult; even slight errors can lead to an imbalance in the refractive index matching between the film layers, not only failing to achieve the antireflection effect but also exacerbating light scattering and reflection, reducing the overall performance of the detector. Although 4H-SiC ultraviolet photodetectors have already shown initial advantages, many technical challenges still need to be overcome on the journey to higher performance. Improving quantum efficiency is one of the key challenges. Current technology still has significant room for improvement in the utilization rate of ultraviolet photons by detectors, meaning that many ultraviolet photons are not effectively converted into electrical signals, resulting in energy waste and limiting further improvements in detector sensitivity. Dark current is also a significant concern. Even with improvements in existing pin structures, in high-precision detection applications that are extremely sensitive to noise, such as biomedical detection and high-end optical instrument calibration, dark current still needs to be reduced to even lower levels. Furthermore, enhancing the stability and reliability of devices to maintain stable performance under long-term, complex, and variable operating environments is also a key focus of current research. Meanwhile, GaN (gallium nitride)-based ultraviolet photodetectors have attracted considerable attention in recent years. With their adjustable response wavelength characteristics, they can flexibly customize the detection range in the ultraviolet band according to different application scenarios, meeting diverse needs. In the field of ultraviolet communication, by precisely adjusting the response wavelength of the GaN detector, high-speed and stable ultraviolet light signal transmission can be achieved, establishing a reliable communication link; in the field of ultraviolet radiation detection, it can focus on specific bands of ultraviolet radiation, providing researchers with more accurate radiation intensity data. The high stability of GaN detectors results in minimal performance fluctuations in complex environments, enabling them to function reliably in both hot and humid tropical rainforest monitoring and cold and dry polar expeditions for ultraviolet detection. Their portability further facilitates their use in field operations and temporary monitoring stations, allowing researchers to quickly deploy them and acquire crucial ultraviolet information promptly. However, traditional GaN-based ultraviolet photodetectors are not without their flaws. High light loss during light signal detection and low light signal absorption efficiency have become bottlenecks in their development.When faced with a weak ultraviolet light source, a large number of photons fail to be effectively absorbed and converted after entering the detector, resulting in a weak electrical signal output by the detector. This makes it difficult to accurately reflect the intensity of the light signal, which limits its detection accuracy and application range in practical applications and fails to meet the growing demand for high-precision ultraviolet detection.

[0005] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure and its fabrication method. Summary of the Invention

[0006] In view of this, the purpose of this invention is to propose a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure and its fabrication method, so as to combine the advantages of multiple materials and overcome the shortcomings of the existing technology.

[0007] To achieve the above objectives, this invention provides a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure and its fabrication method.

[0008] A pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, wherein the ultraviolet photodetector comprises, from bottom to top, an n-type 4H-SiC substrate, an i-type GaN epitaxial layer, and a p-type doped GaN epitaxial layer. The upper surface of the p-type doped GaN epitaxial layer is in contact with the anode electrode, and the lower surface of the n-type 4H-SiC substrate is in contact with the cathode electrode.

[0009] Preferably, the pin-type ultraviolet photodetector is simulated using Silvaco TCAD software. The calculation process employs carrier Fermi statistics and a partial ionization model based on doping concentration, i.e., the electron concentration in the semiconductor is:

[0010]

[0011] The hole concentration in the semiconductor is:

[0012]

[0013] Take the doping concentration N of the p-type GaN epitaxial layer a =5.0×10 18 cm -3 The doping concentration N of the n-type SiC substrate d =2.0×10 18 cm -3 The i-layer is unintentionally doped GaN. Due to the presence of nitrogen vacancies, unintentionally doped GaN typically exhibits an n-type structure, with an electron concentration of around 10⁻⁶. 16 cm -3The magnitude is set, and the width of the i-type GaN is set to 200nm.

[0014] A method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure includes the following steps:

[0015] Step S1. Substrate selection: Select a 6-inch 4H-SiC substrate;

[0016] Step S2. i-GaN intrinsic layer growth stage: Metal-organic chemical vapor deposition technology is used. The reaction chamber temperature is set at 1040-1060℃, the pressure is maintained at 190-210mbar, trimethylgallium is used as the gallium source with a flow rate controlled at 18-22sccm, ammonia is used as the nitrogen source with a flow rate set at 1400-1600sccm, and high-purity hydrogen is used as the carrier gas with a flow rate of 4950-5050sccm. Under these parameters, the growth rate is 0.4-0.6μm / h to ensure the growth of a high-quality i-GaN intrinsic layer with a thickness of 190-210nm.

[0017] Step S3. p-GaN photonic absorption layer growth: Metal-organic chemical vapor deposition (MOCVD) is used, with the temperature maintained at 9950-1050℃ and the pressure at 140-160mbar. The flow rate of trimethylgallium is adjusted to 28-32 sccm, the flow rate of ammonia is 1750-1850 sccm, and the flow rate of hydrogen carrier gas is 5950-6050 sccm. Magnesium dopant is introduced in the form of magnesia-cerocene Cp2Mg, with the flow rate controlled at 0.8-1.2 sccm. After optimization of the growth time, the p-GaN layer thickness is ensured to reach 280-320 nm. This allows for precise control of the electrochemical properties of the p-GaN layer, obtaining the ideal hole carrier velocity and meeting the requirements for efficient ultraviolet light absorption and conversion.

[0018] Step S4. Electrode fabrication: Nickel and aluminum are deposited on the surface of the p-GaN photon absorption layer by vapor deposition. The nickel target has a purity of 99.99%, the evaporation rate is controlled at 0.4-0.6 Å / s, and the deposition thickness reaches 180-220 Å. The Al target has a purity of 99.9%, the evaporation rate is 0.2-0.4 Å / s, and the deposition thickness is 90-110 Å. High-vacuum physical vapor deposition (PVD) is used, with a vacuum level better than 1×10⁻⁶. - 6 Evaporation is performed in an environment of mbar to ensure that metal atoms are uniformly deposited on the p-GaN surface and to promote the formation of good ohmic contacts.

[0019] Step S5. Deposit titanium and aluminum metals onto the lower surface of a 4H-SiC conductive substrate by vapor deposition. The titanium target has a purity of 99.95%, an evaporation rate of 0.3-0.5 Å / s, and a deposition thickness of 145-155 Å. The aluminum target has a purity of 99.9%, an evaporation rate of 0.25-0.35 Å / s, and a deposition thickness of 95-105 Å. The vacuum environment requirements are the same as those for p-GaN surface deposition to ensure a stable and reliable electrical connection between the electrode and the substrate.

[0020] Step S6. Annealing: After the metal electrode evaporation is completed, the device is placed in a professional rapid thermal annealing equipment. Under a nitrogen atmosphere with a purity of 99.999%, it is annealed at 495-505℃ for 2-4 minutes, with the heating rate controlled at 48-52℃ / s to ensure the uniformity and stability of the entire annealing process. This allows for the fine "adjustment" of the detector's internal microstructure, comprehensively improving the detector's performance and enabling it to excel in the field of ultraviolet light detection.

[0021] Preferably, the key parameter requirement of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 are ±0.5%, and the difference in the coefficient of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 is ±1×10⁻⁶. -6 K -1 This ensures the quality of the crystals grown subsequently.

[0022] The beneficial effects of this invention are:

[0023] This invention provides a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure and its fabrication method, offering numerous significant advantages. First, at the material structure level, it greatly reduces dislocation defects, laying a solid foundation for subsequent high-quality crystal growth and ensuring structural stability of the detector under complex operating conditions. This effectively avoids material damage caused by thermal expansion and contraction or lattice stress, significantly improving the detector's reliability and durability. Second, the fabrication process is meticulously detailed. Metal-organic chemical vapor deposition (MOCVD) technology is employed, with precise control of parameters at each stage. Furthermore, in the electrode fabrication stage, high-purity metal combined with an appropriate evaporation rate and deposition thickness, along with high-vacuum physical vapor deposition technology, ensures good ohmic contact between the metal and semiconductor, resulting in high hole injection efficiency, reducing contact resistance to below 1 Ω·cm², decreasing carrier recombination probability, and effectively improving photoelectric conversion efficiency. Compared with existing technologies, this invention overcomes the drawbacks of complex fabrication and poor stability of organic semiconductor thin-film detectors, as well as the low light absorption efficiency of traditional GaN detectors, and has broad market prospects. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only for this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the pin heterostructure ultraviolet photodetector in this invention;

[0026] Figure 2 This is a simulation diagram of the pin heterostructure ultraviolet photodetector in this invention.

[0027] Figure 3 This is a simulation result diagram of dark state IV in this invention;

[0028] Figure 4 This is a simulation result of the spectral response of the present invention;

[0029] Figure 5 The figure shows the simulation results of photocurrent IV. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0031] Example 1: A pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, wherein the ultraviolet photodetector comprises, from bottom to top, an n-type 4H-SiC substrate, an i-type GaN epitaxial layer, and a p-type doped GaN epitaxial layer. The upper surface of the p-type doped GaN epitaxial layer is in contact with the anode electrode, and the lower surface of the n-type 4H-SiC substrate is in contact with the cathode electrode. The structure is as follows: Figure 1 As shown.

[0032] To verify its feasibility, a pin-type ultraviolet photodetector was simulated using Silvaco TCAD software. The calculations employed carrier Fermi statistics and a partial ionization model based on doping concentration, where the electron concentration in the semiconductor was:

[0033]

[0034] The hole concentration in the semiconductor is:

[0035]

[0036] Take the doping concentration N of the p-type GaN epitaxial layer a =5.0×10 18 cm -3The doping concentration N of the n-type SiC substrate d =2.0×10 18 cm -3 The i-layer is unintentionally doped GaN. Due to the presence of nitrogen vacancies, unintentionally doped GaN typically exhibits an n-type structure, with an electron concentration of around 10⁻⁶. 16 cm -3 The order of magnitude is specified, and the width of the i-type GaN is set to 200 nm. The simulated structure is shown below. Figure 2 As shown;

[0037] The anode electrode is in contact with the upper surface of the p-type GaN epitaxial layer, and the cathode electrode is in contact with the back surface of the n-type SiC substrate. Then, an external electric field is applied to the electrodes of the device, and its N-mode characteristic curves in the dark state are measured. Figure 3 As shown;

[0038] It can be observed that in the cutoff region, the dark current can reach 10. -16 Given that the photodetector is essentially a reverse-biased pn junction diode, the reverse bias enhances the internal electric field and widens the depletion layer. Similarly, by increasing the intrinsic GaN region, the depletion layer can be widened, dark current reduced, and the photodetector's responsivity improved. Next, spectral response and photocurrent N-level simulations are performed, and the results are as follows... Figure 4 and Figure 5 As shown;

[0039] The spectral response shows that the device exhibits its maximum photocurrent at 350 nm, approximately 6.0 × 10⁻⁶. -9 A increases linearly in the 200-350nm range, peaks at 350nm and then decreases, approaching zero after 420nm, thus achieving photoelectric detection in the ultraviolet band. Then, by applying light intensity at 350nm, the photocurrent N of the device is analyzed, revealing that at 2V, the photocurrent is 10 times that of the dark current. -16 The A-level has increased to 10. -9 The on / off ratio, on the order of A and approximately 4-5, indicates that the device has significant sensitivity to the ultraviolet band, proving the feasibility of the proposed scheme.

[0040] This invention also provides a method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, as detailed below:

[0041] Example 2: A method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, comprising the following steps:

[0042] S1. Substrate selection: Select a 6-inch 4H-SiC substrate;

[0043] S2. i-GaN Intrinsic Layer Growth: Metal-organic chemical vapor deposition (MOCVD) was employed. The reaction chamber temperature was set at 1040℃, and the pressure was maintained at 190 mbar. Trimethylgallium (TMG) was used as the gallium source, with a flow rate controlled at 18 sccm. Ammonia was used as the nitrogen source, with a flow rate set at 1400 sccm. High-purity hydrogen was used as the carrier gas, with a flow rate of 4950 sccm. Under these parameters, the growth rate was 0.4 μm / h to ensure the growth of a high-quality i-GaN intrinsic layer with a thickness of 190 nm. The key parameter requirements of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 were ±0.5%. The difference in the coefficients of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 was ±1 × 10⁻⁶. -6 K -1 This ensures the quality of the crystals grown subsequently.

[0044] S3. p-GaN photonic absorption layer growth: Metal-organic chemical vapor deposition technology was used, with the temperature maintained at 9950℃ and the pressure at 140mbar. The flow rate of trimethylgallium was adjusted to 28sccm, the flow rate of ammonia was 1750sccm, and the flow rate of hydrogen carrier gas was 5950sccm. Magnesium dopant was introduced in the form of magnesia-cerocene Cp2Mg, with the flow rate controlled at 0.8sccm. After optimization of the growth time, the p-GaN layer thickness was ensured to reach 280nm. This allows for precise control of the electrochemical properties of the p-GaN layer, obtaining the ideal hole carrier velocity and meeting the requirements for efficient ultraviolet light absorption and conversion.

[0045] S4. Electrode Fabrication: Nickel and aluminum were deposited on the surface of the p-GaN photon absorption layer by vapor deposition. The nickel target had a purity of 99.99%, the evaporation rate was controlled at 0.4 Å / s, and the deposition thickness reached 180 Å. The Al target had a purity of 99.9%, the evaporation rate was 0.2 Å / s, and the deposition thickness was 90 Å. High-vacuum physical vapor deposition (PVD) was used at a vacuum of 1×10⁻⁶. -6 Evaporation is performed in an environment of mbar to ensure that metal atoms are uniformly deposited on the p-GaN surface and to promote the formation of good ohmic contacts.

[0046] S5. Titanium and aluminum are vapor-deposited on the lower surface of a 4H-SiC conductive substrate. The titanium target has a purity of 99.95%, an evaporation rate of 0.3 Å / s, and a deposition thickness of 145 Å. The aluminum target has a purity of 99.9%, an evaporation rate of 0.25 Å / s, and a deposition thickness of 95 Å. The vacuum environment requirements are the same as those for p-GaN surface vapor deposition to ensure a stable and reliable electrical connection between the electrode and the substrate.

[0047] S6. Annealing treatment: After the metal electrode evaporation is completed, the device is placed in a professional rapid thermal annealing equipment. Under a nitrogen atmosphere with a purity of 99.999%, it is annealed at 495℃ for 2 minutes with a heating rate controlled at 48℃ / s to ensure the uniformity and stability of the entire annealing process. This allows for the fine "adjustment" of the detector's internal microstructure, comprehensively improving the detector's performance and enabling it to excel in the field of ultraviolet light detection.

[0048] Example 3: A method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, comprising the following steps:

[0049] S1. Substrate selection: Select a 6-inch 4H-SiC substrate;

[0050] S2. i-GaN Intrinsic Layer Growth: Metal-organic chemical vapor deposition (MOCVD) was employed. The reaction chamber temperature was set at 1045℃, and the pressure was maintained at 195 mbar. Trimethylgallium (TMG) was used as the gallium source, with a flow rate controlled at 19 sccm. Ammonia was used as the nitrogen source, with a flow rate set at 1405 sccm. High-purity hydrogen was used as the carrier gas, with a flow rate of 4955 sccm. Under these parameters, the growth rate was 0.5 μm / h to ensure the growth of a high-quality i-GaN intrinsic layer with a thickness of 195 nm. The key parameter requirements of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 were ±0.5%. The difference in the coefficients of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 was ±1 × 10⁻⁶. -6 K -1 This ensures the quality of the crystals grown subsequently.

[0051] S3. p-GaN photonic absorption layer growth: Metal-organic chemical vapor deposition technology was used, with the temperature maintained at 9955℃ and the pressure at 145mbar. The flow rate of trimethylgallium was adjusted to 29sccm, the flow rate of ammonia was 1755sccm, and the flow rate of hydrogen carrier gas was 5955sccm. Magnesium dopant was introduced in the form of magnesia-cerocene Cp2Mg, with the flow rate controlled at 0.9sccm. After optimization of the growth time, the p-GaN layer thickness was ensured to reach 285nm. This allows for precise control of the electrochemical properties of the p-GaN layer, obtaining the ideal hole carrier velocity and meeting the requirements for efficient ultraviolet light absorption and conversion.

[0052] S4. Electrode Fabrication: Nickel and aluminum were deposited on the surface of the p-GaN photon absorption layer by vapor deposition. The nickel target had a purity of 99.99%, the evaporation rate was controlled at 0.5 Å / s, and the deposition thickness reached 185 Å. The Al target had a purity of 99.9%, the evaporation rate was 0.3 Å / s, and the deposition thickness was 95 Å. High-vacuum physical vapor deposition (PVD) was used at a vacuum of 1×10⁻⁶. -6Evaporation is performed in an environment of mbar to ensure that metal atoms are uniformly deposited on the p-GaN surface and to promote the formation of good ohmic contacts.

[0053] S5. Titanium and aluminum are vapor-deposited on the lower surface of a 4H-SiC conductive substrate. The titanium target has a purity of 99.95%, an evaporation rate of 0.4 Å / s, and a deposition thickness of 149 Å. The aluminum target has a purity of 99.9%, an evaporation rate of 0.27 Å / s, and a deposition thickness of 96 Å. The vacuum environment requirements are the same as those for p-GaN surface vapor deposition to ensure a stable and reliable electrical connection between the electrode and the substrate.

[0054] S6. Annealing treatment: After the metal electrode evaporation is completed, the device is placed in a professional rapid thermal annealing equipment. Under a nitrogen atmosphere with a purity of 99.999%, it is annealed at 496℃ for 3 minutes, with the heating rate controlled at 49℃ / s to ensure the uniformity and stability of the entire annealing process. This allows for the fine "adjustment" of the detector's internal microstructure, comprehensively improving the detector's performance and enabling it to excel in the field of ultraviolet light detection.

[0055] Example 4: A method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, comprising the following steps:

[0056] S1. Substrate selection: Select a 6-inch 4H-SiC substrate;

[0057] S2. i-GaN Intrinsic Layer Growth: Metal-organic chemical vapor deposition (MOCVD) was employed. The reaction chamber temperature was set at 1028℃, and the pressure was maintained at 206 mbar. Trimethylgallium (TMG) was used as the gallium source, with a flow rate controlled at 20 sccm. Ammonia was used as the nitrogen source, with a flow rate set at 1580 sccm. High-purity hydrogen was used as the carrier gas, with a flow rate of 5020 sccm. Under these parameters, the growth rate was 0.5 μm / h to ensure the growth of a high-quality i-GaN intrinsic layer with a thickness of 206 nm. The key parameter requirements of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 were ±0.5%. The difference in the coefficient of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 was ±1 × 10⁻⁶. -6 K -1 This ensures the quality of the crystals grown subsequently.

[0058] S3. p-GaN photonic absorption layer growth: Metal-organic chemical vapor deposition technology was used, with the temperature maintained at 1023℃ and the pressure at 152mbar. The flow rate of trimethylgallium was adjusted to 30sccm, the flow rate of ammonia was 1832sccm, and the flow rate of hydrogen carrier gas was 6032sccm. Magnesium dopant was introduced in the form of magnesia-cerocene Cp2Mg, with the flow rate controlled at 1.1sccm. After optimization of the growth time, the p-GaN layer thickness was ensured to reach 318nm. This allows for precise control of the electrochemical properties of the p-GaN layer, obtaining the ideal hole carrier velocity and meeting the requirements for efficient ultraviolet light absorption and conversion.

[0059] S4. Electrode Fabrication: Nickel and aluminum were deposited on the surface of the p-GaN photon absorption layer by vapor deposition. The nickel target had a purity of 99.99%, the evaporation rate was controlled at 0.5 Å / s, and the deposition thickness reached 218 Å. The Al target had a purity of 99.9%, the evaporation rate was 0.3 Å / s, and the deposition thickness reached 108 Å. High-vacuum physical vapor deposition (PVD) was used at a vacuum of 1×10⁻⁶. -6 Evaporation is performed in an environment of mbar to ensure that metal atoms are uniformly deposited on the p-GaN surface and to promote the formation of good ohmic contacts.

[0060] S5. Titanium and aluminum are vapor-deposited on the lower surface of a 4H-SiC conductive substrate. The titanium target has a purity of 99.95%, an evaporation rate of 0.4 Å / s, and a deposition thickness of 153 Å. The aluminum target has a purity of 99.9%, an evaporation rate of 0.32 Å / s, and a deposition thickness of 103 Å. The vacuum environment requirements are the same as those for p-GaN surface vapor deposition to ensure a stable and reliable electrical connection between the electrode and the substrate.

[0061] S6. Annealing treatment: After the metal electrode evaporation is completed, the device is placed in a professional rapid thermal annealing equipment. Under a nitrogen atmosphere with a purity of 99.999%, it is annealed at 503℃ for 3 minutes with a heating rate controlled at 50℃ / s to ensure the uniformity and stability of the entire annealing process. This allows for the fine "adjustment" of the detector's internal microstructure, comprehensively improving the detector's performance and enabling it to excel in the field of ultraviolet light detection.

[0062] Example 5: A method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, comprising the following steps:

[0063] S1. Substrate selection: Select a 6-inch 4H-SiC substrate;

[0064] S2. i-GaN Intrinsic Layer Growth: Metal-organic chemical vapor deposition (MOCVD) was employed. The reaction chamber temperature was set at 1050℃, and the pressure was maintained at 200 mbar. Trimethylgallium (TMG) was used as the gallium source, with a flow rate controlled at 20 sccm. Ammonia was used as the nitrogen source, with a flow rate set at 1500 sccm. High-purity hydrogen was used as the carrier gas, with a flow rate of 4950-5050 sccm. Under these parameters, the growth rate was 0.5 μm / h to ensure the growth of a high-quality i-GaN intrinsic layer with a thickness of 200 nm. The key parameter requirements of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 were ±0.5%. The difference in the coefficient of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 was ±1 × 10⁻⁶. -6 K -1 This ensures the quality of the crystals grown subsequently.

[0065] S3. p-GaN photonic absorption layer growth: Metal-organic chemical vapor deposition technology was used, with the temperature maintained at 1000℃ and the pressure at 150mbar. The flow rate of trimethylgallium was adjusted to 30sccm, the flow rate of ammonia was 1800sccm, and the flow rate of hydrogen carrier gas was 6000sccm. Magnesium dopant was introduced in the form of magnesia-cerocene Cp2Mg, with the flow rate controlled at 0.8-1.2sccm. The growth time was optimized to ensure that the p-GaN layer thickness reached 300nm. This allows for precise control of the electrochemical properties of the p-GaN layer, obtaining the ideal hole carrier velocity and meeting the requirements for efficient ultraviolet light absorption and conversion.

[0066] S4. Electrode Fabrication: Nickel and aluminum were deposited on the surface of the p-GaN photon absorption layer by vapor deposition. The nickel target had a purity of 99.99%, the evaporation rate was controlled at 0.5 Å / s, and the deposition thickness reached 200 Å. The Al target had a purity of 99.9%, the evaporation rate was 0.3 Å / s, and the deposition thickness was 100 Å. High-vacuum physical vapor deposition (PVD) was used at a vacuum level of 1×10⁻⁶. -6 Evaporation is performed in an environment of mbar to ensure that metal atoms are uniformly deposited on the p-GaN surface and to promote the formation of good ohmic contacts.

[0067] S5. Titanium and aluminum are vapor-deposited on the lower surface of a 4H-SiC conductive substrate. The titanium target has a purity of 99.95%, an evaporation rate of 0.4 Å / s, and a deposition thickness of 150 Å. The aluminum target has a purity of 99.9%, an evaporation rate of 0.3 Å / s, and a deposition thickness of 100 Å. The vacuum environment requirements are the same as those for p-GaN surface vapor deposition to ensure a stable and reliable electrical connection between the electrode and the substrate.

[0068] S6. Annealing treatment: After the metal electrode evaporation is completed, the device is placed in a professional rapid thermal annealing equipment. Under a nitrogen atmosphere with a purity of 99.999%, it is annealed at 500℃ for 3 minutes with a heating rate controlled at 50℃ / s to ensure the uniformity and stability of the entire annealing process. This allows for the fine "adjustment" of the detector's internal microstructure, comprehensively improving the detector's performance and enabling it to excel in the field of ultraviolet light detection.

[0069] Example 6: A method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, comprising the following steps:

[0070] S1. Substrate selection: Select a 6-inch 4H-SiC substrate;

[0071] S2. i-GaN Intrinsic Layer Growth: Metal-organic chemical vapor deposition (MOCVD) was employed. The reaction chamber temperature was set at 1059℃, and the pressure was maintained at 209 mbar. Trimethylgallium (TMG) was used as the gallium source, with a flow rate controlled at 21 sccm. Ammonia was used as the nitrogen source, with a flow rate set at 1599 sccm. High-purity hydrogen was used as the carrier gas, with a flow rate of 5049 sccm. Under these parameters, the growth rate was 0.5 μm / h to ensure the growth of a high-quality i-GaN intrinsic layer with a thickness of 209 nm. The key parameter requirements of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 were ±0.5%. The difference in the coefficient of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 was ±1 × 10⁻⁶. -6 K -1 This ensures the quality of the crystals grown subsequently.

[0072] S3. p-GaN photonic absorption layer growth: Metal-organic chemical vapor deposition technology was used, with the temperature maintained at 1049℃ and the pressure at 159mbar. The flow rate of trimethylgallium was adjusted to 31sccm, the flow rate of ammonia was 1845sccm, and the flow rate of hydrogen carrier gas was 6045sccm. Magnesium dopant was introduced in the form of magnesia-cerocene Cp2Mg, with the flow rate controlled at 1.1sccm. The growth time was optimized to ensure that the p-GaN layer thickness reached 319nm. This allows for precise control of the electrochemical properties of the p-GaN layer, obtaining the ideal hole carrier velocity and meeting the requirements for efficient ultraviolet light absorption and conversion.

[0073] S4. Electrode Fabrication: Nickel and aluminum were deposited on the surface of the p-GaN photon absorption layer by vapor deposition. The nickel target had a purity of 99.99%, the evaporation rate was controlled at 0.5 Å / s, and the deposition thickness reached 219 Å. The Al target had a purity of 99.9%, the evaporation rate was 0.3 Å / s, and the deposition thickness reached 109 Å. High-vacuum physical vapor deposition (PVD) was used at a vacuum of 1×10⁻⁶. -6Evaporation is performed in an environment of mbar to ensure that metal atoms are uniformly deposited on the p-GaN surface and to promote the formation of good ohmic contacts.

[0074] S5. Titanium and aluminum are vapor-deposited on the lower surface of a 4H-SiC conductive substrate. The titanium target has a purity of 99.95%, an evaporation rate of 0.4 Å / s, and a deposition thickness of 154 Å. The aluminum target has a purity of 99.9%, an evaporation rate of 0.34 Å / s, and a deposition thickness of 104 Å. The vacuum environment requirements are the same as those for p-GaN surface vapor deposition to ensure a stable and reliable electrical connection between the electrode and the substrate.

[0075] S6. Annealing treatment: After the metal electrode evaporation is completed, the device is placed in a professional rapid thermal annealing equipment. Under a nitrogen atmosphere with a purity of 99.999%, it is annealed at 504℃ for 3 minutes with a heating rate controlled at 51℃ / s to ensure the uniformity and stability of the entire annealing process. This allows for the fine "adjustment" of the detector's internal microstructure, comprehensively improving the detector's performance and enabling it to excel in the field of ultraviolet light detection.

[0076] Example 7: A method for fabricating a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, comprising the following steps:

[0077] S1. Substrate selection: Select a 6-inch 4H-SiC substrate;

[0078] S2. i-GaN Intrinsic Layer Growth: Metal-organic chemical vapor deposition (MOCVD) was employed. The reaction chamber temperature was set at 1060℃, and the pressure was maintained at 210 mbar. Trimethylgallium (TMG) was used as the gallium source, with a flow rate controlled at 22 sccm. Ammonia was used as the nitrogen source, with a flow rate set at 1600 sccm. High-purity hydrogen was used as the carrier gas, with a flow rate of 5050 sccm. Under these parameters, the growth rate was 0.6 μm / h to ensure the growth of a high-quality i-GaN intrinsic layer with a thickness of 210 nm. The key parameter requirements of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 were ±0.5%. The difference in the coefficients of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 was ±1 × 10⁻⁶. -6 K -1 This ensures the quality of the crystals grown subsequently.

[0079] S3. p-GaN photonic absorption layer growth: Metal-organic chemical vapor deposition technology was used, with the temperature maintained at 1050℃ and the pressure at 160mbar. The flow rate of trimethylgallium was adjusted to 32sccm, the flow rate of ammonia was 1850sccm, and the flow rate of hydrogen carrier gas was 6050sccm. Magnesium dopant was introduced in the form of magnesia-cerocene Cp2Mg, with the flow rate controlled at 1.2sccm. The growth time was optimized to ensure that the p-GaN layer thickness reached 320nm. This allows for precise control of the electrochemical properties of the p-GaN layer, obtaining the ideal hole carrier velocity and meeting the requirements for efficient ultraviolet light absorption and conversion.

[0080] S4. Electrode Fabrication: Nickel and aluminum were deposited on the surface of the p-GaN photon absorption layer by vapor deposition. The nickel target had a purity of 99.99%, the evaporation rate was controlled at 0.6 Å / s, and the deposition thickness reached 220 Å. The Al target had a purity of 99.9%, the evaporation rate was 0.4 Å / s, and the deposition thickness reached 110 Å. High-vacuum physical vapor deposition (PVD) was used at a vacuum level of 1×10⁻⁶. -6 Evaporation is performed in an environment of mbar to ensure that metal atoms are uniformly deposited on the p-GaN surface and to promote the formation of good ohmic contacts.

[0081] S5. Titanium and aluminum are vapor-deposited on the lower surface of a 4H-SiC conductive substrate. The titanium target has a purity of 99.95%, an evaporation rate of 0.5 Å / s, and a deposition thickness of 155 Å. The aluminum target has a purity of 99.9%, an evaporation rate of 0.35 Å / s, and a deposition thickness of 105 Å. The vacuum environment requirements are the same as those for p-GaN surface deposition to ensure a stable and reliable electrical connection between the electrode and the substrate.

[0082] S6. Annealing treatment: After the metal electrode evaporation is completed, the device is placed in a professional rapid thermal annealing equipment. Under a nitrogen atmosphere with a purity of 99.999%, it is annealed at 505℃ for 4 minutes with a heating rate controlled at 52℃ / s to ensure the uniformity and stability of the entire annealing process. This allows for the fine "adjustment" of the detector's internal microstructure, comprehensively improving the detector's performance and enabling it to excel in the field of ultraviolet light detection.

[0083] To more clearly demonstrate the advantages of the pin-type ultraviolet photodetector based on the 4H-SiC heterostructure and its fabrication method, the following comparative examples are provided:

[0084] Comparative Example 1:

[0085] A similar structural design as this invention was adopted, but a common 4-inch Si substrate was used instead of the 6-inch 4H-SiC substrate required in this invention, and the matching of the substrate's lattice constant and thermal expansion coefficient with i-GaN was not considered. During the subsequent growth of the i-GaN intrinsic layer, due to severe lattice mismatch, a large number of dislocation defects appeared in the grown i-GaN layer. High-resolution transmission electron microscopy (HRTEM) revealed a dislocation density as high as 1×10¹. 0 cm -2 This is far higher than the dislocation density that can be controlled under suitable substrate conditions (below 1×10⁻⁶). 8 cm -2 These defects act like "traps," trapping a large number of charge carriers and reducing the detector's electron mobility to only 100 cm² / V·s, a significant decrease compared to the detector prepared in this invention (above 500 cm² / V·s), severely impacting the detector's response speed and sensitivity. During the p-GaN photonic absorption layer growth stage, stress issues caused by substrate mismatch also resulted in uneven p-GaN layer thickness, ranging from a minimum of 150 nm to a maximum of 400 nm, causing significant fluctuations in ultraviolet light absorption efficiency, with an average light absorption efficiency approximately 30% lower than that of this invention. Furthermore, in the electrode fabrication stage, due to the poor performance of ohmic contacts between the Si substrate and the metal, the contact resistance reached as high as 10 Ω·cm² after using the same metal evaporation process as this invention. In contrast, this invention, through reasonable selection of the substrate and metal, can control the contact resistance to below 1 Ω·cm². Excessive contact resistance hinders current transmission, significantly reducing the overall performance of the detector.

[0086] Comparative Example 2: In the preparation process, the i-GaN intrinsic layer growth step deviated from the process parameters of this invention. The reaction chamber temperature was set at 950℃, the pressure was maintained at 300 mbar, the trimethylgallium flow rate was 10 sccm, the ammonia flow rate was 1000 sccm, and the carrier gas hydrogen flow rate was 3000 sccm. Under these parameters, the growth rate was only 0.2 μm / h, and the thickness of the grown i-GaN layer was 100 nm, far below the 190-210 nm range required by this invention. Due to the excessively low temperature and the imbalance of the gas source ratio, the quality of the grown i-GaN crystal was extremely poor, with a large number of grain boundary and twin defects. X-ray diffraction (XRD) pattern analysis showed that its crystal quality factor (FWHM value) was deteriorated by about 50% compared to this invention. This resulted in a severe impairment of the i-GaN layer's carrier transport performance, and a significant increase in the detector's dark current, reaching 1 × 10⁻⁻⁻⁶ at a bias voltage of -5V. 8 A is the dark current (1×10⁻¹) under the same bias voltage of this invention. 6 10 (A-level) 8The excessively high dark current significantly increases the noise of the detector under no-light conditions, causing the signal-to-noise ratio to drop sharply and failing to meet the requirements of high-precision detection.

[0087] Comparative Example 3: During the growth of the p-GaN photonic absorption layer, the precise doping process of this invention was not followed. Magnesium dopant was introduced in the form of magnesia-diocene (Cp₂Mg), but the flow rate was controlled at 0.5 sccm, far below the 0.8-1.2 sccm range required by this invention. The resulting p-GaN layer had an excessively low hole carrier concentration, only 1 × 10¹⁸. 6 cm⁻³, compared to the hole carrier concentration achievable by this invention (5 × 10¹ cm⁻³). 8 The difference (approximately cm⁻³) is significant. This results in a severely insufficient absorption and conversion efficiency of the p-GaN layer for ultraviolet light; at the 350nm wavelength, the maximum photocurrent of the device is only 1×10⁻¹. 0 A, and the detector prepared by this invention can achieve a photocurrent of 6.0 × 10⁻ in this wavelength band. 9 A. The photocurrent response capability decreases by about an order of magnitude, and the detector's sensitivity to ultraviolet light signals is significantly reduced, making it unable to effectively perform its photoelectric conversion function.

[0088] Comparative Example 4: In the electrode fabrication stage, when depositing metal on the surface of the p-GaN photon absorption layer, a nickel target with a purity of 99% was selected, the evaporation rate was controlled at 0.3 Å / s, and the deposition thickness reached 150 Å; the aluminum target had a purity of 99%, an evaporation rate of 0.15 Å / s, a deposition thickness of 70 Å, and the vacuum level could only be maintained at 5 × 10⁻⁻⁻⁶. 5 mbar. Due to low metal purity, unreasonable deposition parameters, and poor vacuum environment, the ohmic contact between the metal and the p-GaN surface is poor, resulting in low hole injection efficiency. Testing showed that the injection efficiency was approximately 40% lower than that of the present invention. This increased the recombination probability of photogenerated carriers during detector operation, significantly reducing photoelectric conversion efficiency and making the overall performance inferior to the detector prepared in this invention.

[0089] Comparative Example 5: The annealing process differs from that of this invention. The device is placed in a conventional annealing furnace and annealed at 600°C for 5 minutes in air, with a heating rate of 30°C / s. Annealing in air causes an oxidation reaction at the metal-semiconductor interface, forming an oxide layer that hinders carrier transport. Furthermore, the excessively high annealing temperature and long annealing time lead to an increase in internal defects in the semiconductor layer, such as an approximately 30% increase in nitrogen vacancy concentration in the i-GaN layer. Testing revealed that the detector's responsivity decreased by approximately 20% compared to this invention, and the dark current increased by approximately 50%. The detector's performance stability and reliability were compromised, failing to achieve the high performance level achieved by the refined annealing process of this invention.

[0090] The comparative examples above clearly demonstrate that the meticulous design and precise parameter control in each step of this invention, including substrate selection, epitaxial layer growth process, electrode preparation, and annealing, play a crucial role in the fabrication of a high-performance pin-type ultraviolet photodetector based on a 4H-SiC / GaN heterostructure. Deviating from these key elements will severely impact the detector's performance.

[0091] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0092] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure, characterized in that, The ultraviolet photodetector consists of an n-type 4H-SiC substrate, an i-type GaN epitaxial layer, and a p-type doped GaN epitaxial layer, from bottom to top. The upper surface of the p-type doped GaN epitaxial layer is in contact with the anode electrode, and the lower surface of the n-type 4H-SiC substrate is in contact with the cathode electrode. The pin-type ultraviolet photodetector was simulated using Silvaco TCAD software. The calculations employed carrier Fermi statistics and a partial ionization model based on doping concentration, meaning the electron concentration in the semiconductor was: ； The hole concentration in the semiconductor is: ； Take the doping concentration N of the p-type GaN epitaxial layer a =5.0×10 18 cm -3 The doping concentration N of the n-type SiC substrate d =2.0×10 18 cm -3 The i-layer is unintentionally doped GaN. Due to the presence of nitrogen vacancies, unintentionally doped GaN typically exhibits an n-type structure, with an electron concentration of around 10⁻⁶. 16 cm -3 The order of magnitude is set, and the width of the i-type GaN is set to 200nm. The fabrication method of the pin-type ultraviolet photodetector based on the 4H-SiC-GaN heterostructure includes the following steps: Step S1. Substrate selection: Select a 6-inch 4H-SiC substrate; Step S2. i-GaN intrinsic layer growth: Metal-organic chemical vapor deposition technology is used, with trimethylgallium as gallium source, ammonia as nitrogen source, and hydrogen as carrier gas. The growth rate is 0.4-0.6 μm / h, and an i-GaN intrinsic layer with a thickness of 190-210 nm is grown. Step S3. p-GaN photon absorption layer growth: Metal-organic chemical vapor deposition technology is used, with trimethylgallium as gallium source, ammonia as nitrogen source, hydrogen as carrier gas, and magnesium dopant introduced in the form of magnesia Cp2Mg. The flow rate is controlled at 0.8-1.2 sccm to grow a p-GaN layer with a thickness of 280-320 nm. Step S4. Electrode fabrication: Nickel and aluminum are deposited on the surface of the p-GaN photon absorption layer using high-vacuum physical vapor deposition (PVD) at a vacuum level of 1×10⁻⁶. -6 Evaporation is performed in an environment of mbar to allow metal atoms to be uniformly deposited on the p-GaN surface; Step S5. Deposit titanium and aluminum metals onto the lower surface of a 4H-SiC conductive substrate under a vacuum of 1×10⁻⁶. -6 Evaporation operation is performed in an mbar environment; Step S6. Annealing treatment: After the metal electrode evaporation is completed, the device is placed in a rapid thermal annealing equipment and annealed in an environment with a nitrogen atmosphere purity of 99.999% to obtain a pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure. The key parameter requirements of the 6-inch 4H-SiC substrate in step S1 and the lattice constant mismatch of the i-GaN in step S2 are ±0.5%, and the difference in the coefficient of thermal expansion between the 6-inch 4H-SiC substrate in step S1 and the i-GaN in step S2 is ±1×10⁻⁶. -6 K -1 .

2. The pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure according to claim 1, characterized in that, In step S2, the reaction chamber temperature in the metal-organic chemical vapor deposition technique is 1040-1060℃ and the pressure is 190-210mbar. In step S2, the flow rate of trimethylgallium is 18-22 sccm, the flow rate of ammonia is 1400-1600 sccm, and the flow rate of high-purity hydrogen is 4950-5050 sccm.

3. The pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure according to claim 1, characterized in that, In step S3, the temperature of the metal-organic chemical vapor deposition technique is 9950-1050℃ and the pressure is 140-160mbar.

4. The pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure according to claim 1, characterized in that, In step S3, the flow rate of trimethylgallium is 28-32 sccm, the flow rate of ammonia is 1750-1850 sccm, and the flow rate of carrier hydrogen is 5950-6050 sccm.

5. The pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure according to claim 1, characterized in that, In step S4, the purity of the nickel target is 99.99%, the evaporation rate is controlled at 0.4-0.6 Å / s, and the deposition thickness reaches 180-220 Å; the purity of the aluminum target is 99.9%, the evaporation rate is 0.2-0.4 Å / s, and the deposition thickness is 90-110 Å.

6. The pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure according to claim 1, characterized in that, The titanium target material mentioned in step S5 has a purity of 99.95%, an evaporation rate of 0.3-0.5 Å / s, and a deposition thickness of 145-155 Å. The aluminum target material has a purity of 99.9%, an evaporation rate of 0.25-0.35 Å / s, and a deposition thickness of 95-105 Å.

7. The pin-type ultraviolet photodetector based on a 4H-SiC-GaN heterostructure according to claim 1, characterized in that, The annealing temperature in step S6 is 495-505℃, the annealing time is 2-4 min, and the heating rate is 48-52℃ / s.

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