A method for synthesizing si c artificial grain boundaries

Abstract

The application discloses a SiC artificial grain boundary synthesis method, which is a precise method for preparing SiC artificial grain boundaries with arbitrary angles and types by using a single crystal silicon carbide substrate. The preparation process comprises the following steps: firstly, the single crystal SiC substrate is cut; then, the single crystal SiC substrate is chemically cleaned to remove possible contamination and an oxide layer; subsequently, the cleaned single crystal SiC substrate is subjected to surface hydrogenation treatment to ensure that the single crystal SiC substrate remains in an oxidation layer-free state in the air for a long time; finally, the single crystal SiC substrate subjected to the hydrogenation treatment is transferred into a hot press furnace for pressing. The application ensures that the surface of the single crystal SiC substrate remains in a clean state for a long time by improving a series of chemical cleaning and high-temperature hydrogenation treatment steps. In combination with the use of the hot press furnace, SiC artificial grain boundaries with arbitrary orientations can be accurately prepared.

Description

Technical Field

[0001] This invention relates to the field of new material preparation technology, specifically to a method for synthesizing SiC artificial grain boundaries. Background Technology

[0002] The properties of materials are often influenced by grain boundaries because they affect the movement and evolution of defects within the material. For example, grain boundaries can hinder dislocation movement, trap various point defects, and provide rapid pathways for defect diffusion, thus affecting the material's macroscopic properties such as mechanical and thermal properties. Simultaneously, changes in the atomic structure and chemical composition of the interface region typically significantly alter the material's mechanical strength, corrosion resistance, and radiation damage resistance. Interfaces include grain boundaries, subgrain boundaries, and phase boundaries. Under irradiation conditions, bombardment by incident particles (such as neutrons and ions) generates numerous Frankel defect pairs in the target material. These defects can combine to form defect recombination, diffuse and aggregate to form defect clusters, or migrate to defect-trapping regions such as surfaces and interfaces, where they accumulate and evolve, severely impacting the material's properties.

[0003] Radiation-induced segregation (RIS) is one of the most significant changes that can occur at grain boundaries in irradiated materials. It has been found in alloys. Radiation-induced segregation ( RIS ） This is because the diffusion rates of atomic defects of different elements generated by irradiation are different. The flux of defects diffusing to grain boundaries may not match the original composition, thus causing segregation of certain element atoms near the grain boundaries. Although RIS is a relatively common phenomenon in metals, due to the significant differences in chemical bonds and lattice structure between ceramic materials and metal materials (such as higher bond energies, defect migration barriers, melting points, etc.), the migration and diffusion of irradiation-induced defects in ceramic materials is more difficult. The question remains whether RIS exists in ceramic materials. Radiation-induced Guided bias analysis ( RIS ） The phenomenon remains unclear.

[0004] The synthesis of SiC artificial grain boundaries in the current technology faces challenges. The synthesized grain boundaries have two major defects that cause them to differ greatly from real natural grain boundaries, making them unsuitable as an effective means to gain in-depth and quantitative understanding of grain boundary properties.

[0005] First, the synthesized grain boundaries are not tightly bonded, resulting in large gaps in the grain boundary region, which easily leads to cracking and failure during performance testing. Second, the grain boundary region of the synthesized artificial grain boundary is always accompanied by a 2-5nm oxide layer. This is due to the oxidation of the SiC surface during the synthesis process, while natural grain boundaries do not have an oxide layer. The presence of this oxide layer makes the chemical composition and microstructure of the artificially synthesized grain boundary very different from those of the natural grain boundary, thus making artificial grain boundaries unsuitable as a method for quantitatively studying grain boundary characteristics.

[0006] Maintaining a clean SiC surface and eliminating the oxide layer during the synthesis of artificial grain boundaries is a major challenge. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for synthesizing SiC artificial grain boundaries that allows for precise control of grain boundary angles and types. The grain boundaries synthesized by this method are tightly bonded, with clean surfaces and no oxide layer.

[0008] This invention provides the following technical solution: A method for synthesizing SiC artificial grain boundaries, the method comprising the following steps: S1. Cut the single-crystal SiC substrate according to the required grain boundary orientation; S2. Perform chemical cleaning on the single-crystal SiC substrate wafer to remove contaminants and oxide layers; S3. Perform surface hydrogenation treatment on the cleaned single-crystal SiC substrate wafer to further remove the surface oxide layer and form a hydrogenation film on the surface to ensure that the wafer remains free of oxide layer in the air for a long time. S4. Transfer the hydrogenated single-crystal SiC substrate wafer to a hot press furnace for pressing.

[0009] Chemical cleaning includes the following steps: S21. Clean the wafer with piranha solution at 170-190℃ for 20-25 minutes. The mass of the solution must be greater than 100 times the total mass of the single crystal SiC substrate wafer used. Immerse the wafer in the piranha solution and heat it with a heater, maintaining the temperature at 170-190℃ for 20-25 minutes. S22. Rinse with running deionized water for 3-6 minutes, remove the wafer, and repeat the rinsing process; S23. Clean the wafer with HF at room temperature for 1.5-2.5 hours. The HF concentration should be higher than 35%. The mass of the solution should be more than 100 times the total mass of the single crystal SiC substrate wafer used. Repeat the cleaning operation by immersing the wafer in the HF solution and cleaning at room temperature for 1.5-2.5 hours. S24. Rinse with running deionized water for 3-6 minutes, remove the wafer, and repeat the rinsing process; S25. Clean the wafer for 10-20 minutes at 70-90℃ with a mixed solution of H2O, H2O2 and HCl in a volume ratio of 4:1:1. Immerse the wafer in the mixed solution and clean it for 10-20 minutes at 70-90℃. S26. Rinse with running deionized water for 3-6 minutes, remove the wafer, and repeat the rinsing process; S27. Clean the wafer with diluted HF for 12-18 minutes at room temperature. The HF concentration should be greater than 5%, and the mass of the solution should be greater than 100 times the total mass of the single crystal SiC substrate wafer used. Place the wafer in the diluted HF solution and clean it at room temperature for 12-18 minutes. S28. Afterwards, clean the single-crystal SiC substrate with anhydrous ethanol. The mass of anhydrous ethanol used must be greater than 100 times the total mass of the single-crystal SiC substrate wafer. S29. Rinse with running deionized water for 8-12 minutes, remove the wafer, and repeat the rinsing operation; the cleaned sample was tested by XPS, and a very weak oxygen peak was found on the surface.

[0010] In step S3, the cleaned single-crystal SiC wafer is placed in a tube furnace, and the vacuum in the vacuum chamber is evacuated to below 9 × 10⁻⁶ using a mechanical pump and a turbomolecular pump. -4 The sample was charged and vented twice, then annealed for 1-2 hours in pure hydrogen at 0.10-0.12 MPa and 1000-1100℃ for 1-2 hours. The single-crystal SiC substrate wafer was placed in a tube furnace, and a hydrogen atmosphere of 0.10-0.12 MPa was established, maintaining the temperature at 1000-1100℃ for annealing under these conditions for 1-2 hours. XPS analysis of the hydrogenated sample revealed no impurity or oxygen peaks on the surface, indicating complete removal of surface impurities and oxide layers.

[0011] In step S4, the hydrogenated single-crystal SiC substrate wafer is placed into a graphite mold and transferred to a hot press furnace for bonding.

[0012] Furthermore, the vacuum degree is <5×10 -3 The pressing temperature is 1000-1100℃, the pressing pressure is 30-40MPa, and the pressing time is at least 20 hours.

[0013] Furthermore, the piranha solution is a mixture of H2SO4 and H2O2 in a volume ratio of 4:1.

[0014] Furthermore, the resistance of flowing deionized water is greater than 18 MΩ.

[0015] Compared with existing technologies, the advantages of this invention are as follows: By improving a series of chemical cleaning and high-temperature hydrogenation treatment steps, this invention ensures that the surface of single-crystal SiC substrates remains clean for a long time; and with the use of a hot press furnace, SiC artificial grain boundaries of arbitrary orientation can be precisely prepared. This provides the possibility for further research on the grain boundary effect and corresponding mechanism of SiC materials. The advantage of this invention lies in the preparation of SiC artificial grain boundaries with precise angles and types (the precise angles and types can be determined through sample cutting and pressing processes), providing researchers with an important means to deeply understand the influence of grain boundaries on material properties. This invention has broad application prospects and can promote the further development and application of SiC materials in the fields of materials science and engineering. Attached Figure Description

[0016] Figure 1 Low-magnification SEM image of the synthesized artificial grain boundaries.

[0017] Figure 2 The image shows the transmission electron backscatter diffraction (tEBSD) pattern of the grain boundary region of the corresponding artificial grain boundary sample.

[0018] Figure 3 The image shows an atomic resolution TEM image of a natural grain boundary a (grain boundary angle of 59 degrees) and the corresponding chemical composition curve.

[0019] Figure 4 The image shows an atomic resolution TEM image of a natural grain boundary b (grain boundary angle of 45 degrees) and the corresponding chemical composition curve.

[0020] Figure 5 The image shows an atomic resolution TEM image of a natural grain boundary c (grain boundary angle of 56 degrees) and the corresponding chemical composition curve.

[0021] Figure 6 The image shows an atomic resolution TEM image of artificial grain boundary a (grain boundary angle of 5 degrees) and the corresponding chemical composition curve.

[0022] Figure 7 The image shows an atomic resolution TEM image of artificial grain boundary b (grain boundary angle of 15 degrees) and the corresponding chemical composition curve.

[0023] Figure 8 The image shows an atomic resolution TEM image of an artificial grain boundary c (grain boundary angle of 30 degrees) and the corresponding chemical composition curve.

[0024] Figure 9 XPS images of the surface of a SiC substrate after cleaning using different methods according to the present invention.

[0025] Figure 10 This is a transmission electron microscope image of the artificial grain boundary prepared in this invention. Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The present invention provides a method for synthesizing SiC artificial grain boundaries, and the specific preparation steps are as follows: Step 1: Sample Cutting; Before the experiment, according to the required grain boundary orientation, use a diamond pen to cut 4H-SiC or 6H-SiC single-crystal SiC substrates into square pieces measuring 1cm × 1cm and 0.5mm thick. The single-crystal SiC substrates were purchased from Nanjing Haoyue Optoelectronics. The angle and type are precisely determined through sample cutting and subsequent lamination processes.

[0028] Step 2: Perform chemical cleaning on the single-crystal SiC substrate wafer to remove possible contaminants and oxide layers; Example 1:

[0029] 1. Clean the wafer for 20 minutes at 170-190℃ using a piranha solution (H2SO4 and H2O2 mixed in a volume ratio of 4:1, with an error of less than 5%). The mass of the solution must be greater than 100 times the total mass of the SiC single crystal used. Immerse the wafer in the piranha solution, heat it with a heater, maintain the temperature at 170-190℃, and clean it for 20 minutes. 2. Rinse with running deionized water (resistance greater than 18MΩ) for 3 minutes, then remove the wafer and place it in running deionized water for another 3 minutes. 3. Clean the wafer with HF (concentration higher than 35%) at room temperature for 1.5 hours. The mass of the solution must be more than 100 times the total mass of the SiC single crystal used. Place the wafer in the HF solution, keep it at room temperature, and clean for 1.5 hours. 4. Rinse with running deionized water (resistance greater than 18MΩ) for 3 minutes, then remove the wafer and place it in running deionized water for another 3 minutes. 5. Clean the wafer for 10 minutes at 70°C with a mixed solution of H2O, H2O2 and HCl in a volume ratio of 4:1:1. Immerse the wafer in the mixed solution and clean it for 10 minutes at 70°C. 6. Rinse with running deionized water (resistance greater than 18MΩ) for 3 minutes, then remove the wafer and place it in deionized water for another 3 minutes. 7. Clean the wafer with diluted HF (concentration higher than 5%) at room temperature for 12 minutes. The mass of the solution should be more than 100 times the total mass of the SiC single crystal used. Place the wafer in the diluted HF solution, keep it at room temperature, and clean for 12 minutes. 8. Clean the single-crystal SiC substrate with anhydrous ethanol whose mass is 100 times greater than the total mass of the single-crystal SiC substrate wafer used; 9. Rinse with flowing deionized water (resistance greater than 18MΩ) for 8 minutes, remove the wafer, place it in deionized water, and rinse for 8 minutes; the cleaned sample was tested by XPS and only a very weak oxygen peak was present on the surface. With the subsequent hydrogenation step, the surface impurities and oxide layer can be completely removed. Example 2:

[0030] 1. Clean the wafer at 180°C for 22 minutes using a piranha solution (H2SO4 and H2O2 mixed in a volume ratio of 4:1, with an error of less than 5%). The mass of the solution must be greater than 100 times the total mass of the SiC single crystal used. Immerse the wafer in the piranha solution, heat it with a heater, maintain the temperature at 180°C, and clean it for 22 minutes. This is to remove possible organic contaminants and impurities from the surface of the SiC single crystal substrate. 2. Rinse with running deionized water (resistance greater than 18MΩ) for 5 minutes, then remove the wafer and place it in running deionized water for another 5 minutes. 3. Clean the wafer with HF (concentration higher than 35%) at room temperature for 2 hours. The mass of the solution must be more than 100 times the total mass of the SiC single crystal used. Place the wafer in the HF solution, keep it at room temperature, and clean for 2 hours. 4. Rinse with running deionized water (resistance greater than 18MΩ) for 5 minutes, then remove the wafer and place it in running deionized water for another 5 minutes. 5. Clean the wafer for 15 minutes at 80°C with a mixed solution of H2O, H2O2 and HCl in a volume ratio of 4:1:1. Immerse the wafer in the mixed solution and clean it for 15 minutes at 80°C. 6. Rinse with running deionized water (resistance greater than 18MΩ) for 5 minutes, then remove the wafer and place it in deionized water for another 5 minutes. 7. Clean the wafer with diluted HF (concentration higher than 5%) at room temperature for 15 minutes. The mass of the solution should be more than 100 times the total mass of the SiC single crystal used. Place the wafer in the diluted HF solution, keep it at room temperature, and clean for 15 minutes. 8. Clean the single-crystal SiC substrate with anhydrous ethanol whose mass is 100 times greater than the total mass of the single-crystal SiC substrate wafer used; 9. Rinse with flowing deionized water (resistance greater than 18MΩ) for 10 minutes, remove the wafer, place it in deionized water, and rinse for 10 minutes; the cleaned sample was tested by XPS and only a very weak oxygen peak was present on the surface. With the subsequent hydrogenation step, the surface impurities and oxide layer can be completely removed. Example 3:

[0031] 1. Clean the wafer at 190°C for 25 minutes using a piranha solution (H2SO4 and H2O2 mixed in a volume ratio of 4:1 with an error of less than 5%). The mass of the solution must be greater than 100 times the total mass of the SiC single crystal used. Immerse the wafer in the piranha solution, heat it with a heater, maintain the temperature at 190°C, and clean it for 25 minutes. 2. Rinse with running deionized water (resistance greater than 18MΩ) for 6 minutes, then remove the wafer and place it in running deionized water for another 6 minutes. 3. Clean the wafer with HF (concentration higher than 35%) at room temperature for 2.5 hours. The mass of the solution must be more than 100 times the total mass of the SiC single crystal used. Place the wafer in the HF solution, keep it at room temperature, and clean for 2.5 hours. 4. Rinse with running deionized water (resistance greater than 18MΩ) for 6 minutes, then remove the wafer and place it in running deionized water for another 6 minutes. 5. Clean the wafer for 20 minutes at 90°C with a mixed solution of H2O, H2O2 and HCl in a volume ratio of 4:1:1. Immerse the wafer in the mixed solution and clean it for 20 minutes at 90°C. 6. Rinse with running deionized water (resistance greater than 18MΩ) for 6 minutes, then remove the wafer and place it in deionized water for another 6 minutes. 7. Clean the wafer for 18 minutes at room temperature with diluted HF (concentration higher than 5%). The mass of the solution must be more than 100 times the total mass of the SiC single crystal used. Place the wafer in the diluted HF solution, keep it at room temperature, and clean for 18 minutes. 8. Clean the single-crystal SiC substrate with anhydrous ethanol whose mass is 100 times greater than the total mass of the single-crystal SiC substrate wafer used; 9. Rinse with flowing deionized water (resistance greater than 18MΩ) for 12 minutes, remove the wafer, place it in deionized water, and rinse for 12 minutes; the cleaned sample was tested by XPS and only a very weak oxygen peak was present on the surface. With the subsequent hydrogenation step, the surface impurities and oxide layer can be completely removed.

[0032] Examples 1-3 above describe the chemical cleaning of single-crystal SiC substrate wafers. Step 1 involves cleaning with piranha solution to remove potential organic contaminants and impurities from the SiC single-crystal substrate surface. Step 2 involves repeated cleaning with flowing deionized water to remove any residual piranha solution from the SiC surface. Step 3 involves cleaning the wafer with HF at room temperature to remove the oxide layer on the SiC surface. The presence of an oxide layer on the artificially synthesized grain boundaries prevents them from being used for quantitative analysis of grain boundary characteristics. Step 4 involves further cleaning with flowing deionized water to remove any residual HF from the SiC surface. Step 5 involves cleaning with a 4:1:1 volume ratio mixture of H₂O, H₂O₂, and HCl to form another artificial oxide film on the SiC surface, preparing for further surface cleaning. Step 6 involves cleaning with flowing deionized water to remove any possible H₂O₂ and HCl residues from the SiC surface. Step 7 involves cleaning the wafer with diluted HF at room temperature to further remove the oxide layer on the SiC surface. Step 8 involves cleaning with flowing deionized water to remove any remaining HF and clean the surface.

[0033] The above cleaning steps all serve a purpose in ensuring the removal of contaminants and oxide layers, leaving the surface clean and ready for subsequent hydrogenation treatment.

[0034] Step 3: Perform hydrogenation treatment to further remove the oxide layer and form a hydrogenation film on the surface to ensure that there is no oxidation on the wafer surface; The cleaned wafers are placed in a tube furnace, and the vacuum chamber is evacuated to below 9 × 10⁻⁶ using a mechanical pump and a turbomolecular pump. -4 The SiC single crystal wafer was annealed for 1-2 hours in a pure hydrogen atmosphere (99.99%) at 0.10-0.12 MPa and 1000-1100℃ for two cycles of charging and degassing. The wafer was placed in a tube furnace, and a hydrogen atmosphere of 0.10-0.12 MPa was established, maintaining the temperature at 1000-1100℃. This 1000-1100℃ hydrogen atmosphere ensures good contact between the SiC material and hydrogen, resulting in Si-H bond formation on the surface, but without excessive reaction producing gases such as silanes, which could lead to material loss and changes in chemical composition. Annealing was performed under these conditions for 1-2 hours. The hydrogenated sample was then tested by XPS. XPS analysis revealed no impurity peaks or oxygen peaks on the surface (e.g., ...). Figure 9 (as shown) Step 4: Vacuum pressing in a hot press furnace After hydrogenation, the single-crystal SiC substrate wafer is placed in a graphite mold and transferred to a hot press furnace for bonding, with a vacuum degree <5×10⁻⁶. -3 The pressing temperature is 1000-1100℃, and the pressing pressure is 30-40MPa. This pressure can ensure that the SiC grain boundaries are sufficiently dense. Previously, artificial synthesis methods used 15MPa, but the synthesized grain boundaries were too loose, and the pressing time was at least 20 hours.

[0035] Artificial grain boundaries for SiC ceramics were synthesized using this method, such as... Figure 10 The specific grain boundary types and angles are shown in Table 1:

[0036] The morphology and angles of the fabricated artificial grain boundaries were analyzed using SEM and transmission electron backscatter diffraction (tEBSD), such as... Figure 1 , 2 As shown, both images have the same magnification. This illustrates the color-crystal orientation relationship in the tEBSD spectrum. The method of this invention can accurately prepare grain boundaries of specific orientations and types, and experiments have demonstrated that the synthesized grain boundaries have a very strong consistency with the chemical composition and properties of real grain boundaries.

[0037] SEM images were obtained using a FEI Helios PFIB G4 FIB / FESEM system, and the sample was then transferred to a FEI Titan to obtain bright-field (BF) transmission electron microscopy (TEM) images. By comparing the contrast of the tEBSD pattern and the BF-TEM images, the position and angular orientation of the GBs displayed in the BF-TEM images were determined. Based on the tEBSD analysis, the torsion angle of the GBs was 29.8° and the tilt angle was 5.6°, which is almost perfectly consistent with the design values ​​(30° torsion and 5.6° tilt) with an error of less than 1.0%.

[0038] Simultaneously, the chemical composition of grain boundaries in multiple natural polycrystalline SiC samples and the artificial grain boundaries synthesized in this invention was analyzed using electron energy loss spectroscopy based on aberration-corrected transmission electron microscopy (TEM), and atomically resolved microscopic morphology images were captured. Combined with... Figure 3 , Figure 4 , Figure 5 and Figure 6 , Figure 7 , Figure 8 It can be seen that the artificial grain boundaries prepared by this invention are consistent with natural grain boundaries in both microstructure and chemical composition, and can play a good substitution role.

[0039] This invention also investigates radiation-induced segregation (RIS) at natural and artificial grain boundaries. RIS is one of the most significant changes that can occur at grain boundaries in irradiated materials. RIS observed in alloys is due to the different diffusion rates of atomic defects of different elements generated by irradiation. The flux of defects diffusing to the grain boundary may not match the original composition, thus causing segregation of certain element atoms near the grain boundary. Although RIS is relatively common in metals, the migration and diffusion of irradiated defects in ceramics are more difficult due to significant differences in chemical bonding and lattice structure compared to metals (e.g., higher bond energies, defect migration barriers, melting points, etc.). Therefore, the existence of RIS in ceramics remains unclear.

[0040] Precise and controllable artificial grain boundaries of SiC were synthesized using single-crystal SiC. Combining a series of new experimental techniques, the RIS phenomenon of SiC grain boundaries after irradiation was successfully observed for the first time, and the effects of temperature and grain boundary type on RIS were studied.

[0041] Studies have found that the carbon (C) content in the grain boundary regions of unirradiated SiC materials is below 50%. However, after irradiation at room temperature and 300℃, the C content in these regions increases significantly, reaching 50% at an irradiation dose of 1 dPa and 53% at 3 dPa. When the irradiation temperature rises to 600℃, the C content in the grain boundary regions not only does not increase but decreases significantly to around 41%. Theoretical calculations reveal that the irradiation-induced segregation phenomenon in SiC materials is due to the different defect recombination and migration energies of Si and C. C defects have higher recombination and lower migration energies than Si defects. Therefore, at low temperatures, C defect atoms migrate to the grain boundary regions, leading to an increase in C content in these regions, while at high temperatures, they recombine, resulting in a decrease. The study found that both types of grain boundaries exhibit the same variation pattern: artificial grain boundaries are consistent with natural grain boundaries in terms of properties and microscopic behavior.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for synthesizing SiC artificial grain boundaries, characterized in that: The synthesis method includes the following steps: S1. Cut the single-crystal SiC substrate according to the required grain boundary orientation; S2. Perform chemical cleaning on the single-crystal SiC substrate wafer to remove contaminants and oxide layers; Chemical cleaning includes the following steps: S21. Clean the wafer at 180°C for 22 minutes using a piranha solution. The piranha solution is a mixture of H2SO4 and H2O2 in a volume ratio of 4:

1. The mass of the solution must be greater than 100 times the total mass of the single-crystal SiC substrate wafer used. Immerse the wafer in the piranha solution and heat it with a heater, maintaining the temperature at 180°C for 22 minutes. S22. Rinse with flowing deionized water with a resistance greater than 18 MΩ for 5 minutes, remove the wafer, and repeat the rinsing operation; S23. Clean the wafer with HF at room temperature for 2 hours. The HF concentration is higher than 35%. The mass of the solution must be more than 100 times the total mass of the single crystal SiC substrate wafer used. Repeat the cleaning operation by placing the wafer in the HF solution and cleaning at room temperature for 2 hours. S24. Rinse with flowing deionized water with a resistance greater than 18 MΩ for 5 minutes, remove the wafer, and repeat the rinsing operation; S25. Clean the wafer at 80°C for 15 minutes with a 4:1:1 mixture of H2O, H2O2 and HCl. Immerse the wafer in the mixture and clean it at 80°C for 15 minutes. S26. Rinse with flowing deionized water with a resistance greater than 18 MΩ for 5 minutes, remove the wafer, and repeat the rinsing operation; S27. Clean the wafer with diluted HF for 15 minutes at room temperature. The HF concentration should be greater than 5%, and the mass of the solution should be greater than 100 times the total mass of the single crystal SiC substrate wafer used. Place the wafer in the diluted HF solution and clean it at room temperature for 15 minutes. S28. Afterwards, clean the single-crystal SiC substrate with anhydrous ethanol. The mass of anhydrous ethanol used must be greater than 100 times the total mass of the single-crystal SiC substrate wafer. S29. Rinse with running deionized water for 10 minutes, remove the wafer, and repeat the rinsing operation; the cleaned sample was tested by XPS, and a very weak oxygen peak was found on the surface; S3. The cleaned single-crystal SiC substrate wafer undergoes surface hydrogenation treatment to further remove the surface oxide layer and form a hydrogenation film on the surface to ensure that the wafer remains oxide-free for a long time in air. In step S3, the cleaned single-crystal SiC wafer is placed in a tube furnace, and the vacuum in the vacuum chamber is evacuated to below 9 × 10⁻⁶ using a mechanical pump and a turbomolecular pump. -4 Pa, charge and vent twice, anneal in pure hydrogen at 0.10-0.12 MPa and 1000℃-1100℃ for 1-2 hours, place the single crystal SiC substrate wafer in a tube furnace, establish a hydrogen atmosphere of 0.10-0.12 MPa, maintain the temperature at 1000℃-1100℃, and perform annealing under these conditions for 1-2 hours; S4. Place the hydrogenated single-crystal SiC substrate wafer into a graphite mold and transfer it to a hot press furnace for pressing, with a vacuum degree <5×10⁻⁶. -3 The pressing temperature is 1000-1100℃, the pressing pressure is 30-40MPa, and the pressing time is at least 20 hours.

2. The method for synthesizing SiC artificial grain boundaries according to claim 1, characterized in that: The single-crystal SiC substrate is a 6H-SiC single-crystal substrate, and the cut substrate is a square piece of 1 cm × 1 cm with a thickness of 0.5 mm.

3. The method for synthesizing SiC artificial grain boundaries according to claim 1, characterized in that: After step S2, the cleaned sample was tested by XPS, and a very weak oxygen peak was found on the surface; after step S3, the hydrogenated sample was tested by XPS, and no impurity peaks or oxygen peaks were found on the surface.

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