Method for growing high-mobility heavily doped single crystal diamond using solid boron source
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-04-22
- Publication Date
- 2026-07-10
AI Technical Summary
Existing MPCVD boron doping processes introduce non-doped source impurities, making it difficult to achieve high-concentration boron doping, which leads to a decline in the performance of diamond devices.
High-migration, heavily doped single-crystal diamond was grown by using a solid boron source via microwave plasma chemical vapor deposition, combined with hydrogen and methane gases, and controlling growth parameters.
High-quality, high-mobility heavily doped single-crystal diamond growth was achieved, meeting the requirements for electronic device fabrication and avoiding the safety risks and impurity introduction problems of gaseous boron sources.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of diamond doping growth technology, specifically relating to a method for growing highly mobile, heavily doped single-crystal diamond using a solid boron source. Background Technology
[0002] Diamond, as a typical ultrawide bandgap semiconductor material (bandgap of approximately 5.5 eV), possesses ultra-high thermal conductivity (22 W / (cm·K)), extremely high breakdown field strength, excellent carrier mobility, chemical stability, and radiation resistance. It is a core candidate material for breaking through the performance limits of traditional semiconductor materials and has irreplaceable application prospects in high-temperature, high-frequency power devices, deep-ultraviolet photodetectors, quantum devices, high-power microwave communication, and electronic components for extreme environments. Intrinsic diamond is an insulator with extremely low carrier concentration, making it unsuitable for direct use in semiconductor device fabrication. Currently, p-type doping of diamond is the only mature method, and boron atoms, as acceptor impurities, can effectively introduce hole carriers, enabling a controllable transition from an insulating to a conductive state. Heavily doped single-crystal diamond is key to achieving low-resistance ohmic contacts and improving device conduction efficiency, while high carrier mobility is a core indicator for ensuring high-frequency, high-power operation. Synergistic optimization of these two aspects is a crucial prerequisite for diamond semiconductors to move from the laboratory to engineering applications.
[0003] Currently, the mainstream technology for preparing high-quality single-crystal diamond is microwave plasma chemical vapor deposition (MPCVD). This method can achieve homoepitaxial growth of low-defect single crystals and is the preferred process for diamond semiconductor growth. Existing MPCVD boron doping processes generally use gaseous boron sources, including organic boron gases such as borane (B2H6), trimethylboron, and trimethyl borate. These doping methods face multiple insurmountable technical bottlenecks in practical applications, directly restricting the preparation of highly mobile, heavily doped single-crystal diamonds. Borane is a highly toxic, flammable, and explosive gas, requiring extremely high standards for equipment sealing, exhaust gas treatment, and operational safety, resulting in significant risks for large-scale production. Organic liquid boron sources need to be vaporized and diluted before being introduced into the reaction chamber, which is easily affected by factors such as vaporization efficiency, gas flow fluctuations, and pipeline adsorption. It is difficult to achieve precise and stable control of the boron atom concentration, especially in the heavy doping stage, where local enrichment of the boron source is prone to occur, leading to lattice distortion and impurity scattering. The uneven distribution of gaseous boron sources in plasma easily leads to non-uniform doping of boron atoms in diamond epitaxial layers, forming localized high-concentration doped regions and defect centers. Simultaneously, gaseous sources readily introduce additional defects such as hydrocarbon residues and oxygen impurities. These defects, along with boron impurities, form carrier scattering centers, resulting in a sharp decrease in hole mobility after heavy doping. Addressing the inherent defects of gaseous boron sources, solid-state boron sources, with their advantages of being non-toxic, chemically stable, having controllable doping concentrations, and lacking gaseous residual impurities, have become an ideal solution to overcome existing doping bottlenecks. Solid-state boron sources can achieve uniform and rapid release of boron atoms through thermal evaporation and plasma-assisted dissociation, avoiding the gas flow fluctuations and impurity introduction problems of gaseous sources. This effectively reduces the defect density of the epitaxial layer, providing a technological possibility for balancing heavy doping and high mobility.
[0004] Currently, there are also studies and reports on the solid-state boron-doped growth of diamond. Yap et al. in Singapore used boron (BN) as a boron source for doping; Yao Kaili et al. mixed graphite powder and boron powder and pressed them into a sheet to achieve doping. The former, using BN, leads to the incorporation of nitrogen (N), making it difficult to achieve high-concentration boron doping. The latter, mixing and pressing, greatly increases the carbon concentration, making it difficult to achieve high-quality, heavily doped growth of single-crystal diamond, which cannot meet the requirements for device fabrication. Summary of the Invention
[0005] The present invention aims to solve the problem that the existing MPCVD boron doping process introduces other non-doped source impurities and makes it difficult to achieve high concentration boron doping, and provides a method for growing highly mobile, heavily doped single-crystal diamond using a solid boron source.
[0006] The present invention utilizes a solid-state boron source to achieve the growth of highly mobile, heavily doped single-crystal diamond, which is implemented according to the following steps:
[0007] Step 1: Diamond leveling treatment:
[0008] The surface of a single-crystal diamond substrate is polished to obtain a polished diamond substrate.
[0009] Step 2, Surface Cleaning:
[0010] The polished diamond substrate was placed in a strong oxidizing mixed acid for high-temperature heating treatment, then immersed in plasma water for heating treatment, and ultrasonically cleaned to obtain a diamond substrate with oxygen terminals.
[0011] Step 3, Doping Growth:
[0012] In the cavity of a microwave plasma chemical vapor deposition apparatus, a single-crystal diamond substrate with oxygen terminals is placed on a solid boron sheet, which is then placed on a molybdenum support. A mixture of hydrogen and methane is introduced, with the hydrogen flow rate controlled at 100 sccm to 500 sccm, the methane concentration at 0.5% to 10%, the diamond substrate temperature at 700℃ to 1100℃, and the solid boron sheet temperature at 600℃ to 1200℃. A boron-doped diamond film is grown on the surface of the diamond substrate, resulting in a substrate with a boron-doped diamond film.
[0013] Step 4: Clean the surface again:
[0014] The substrate on which boron-doped diamond films are grown is placed in a strong oxidizing mixed acid for high-temperature heating treatment, then immersed in plasma water for heating treatment, and ultrasonically cleaned, thus completing the method of growing high-migration heavily doped single-crystal diamond using a solid boron source.
[0015] This invention employs chemical vapor deposition to grow a heavily boron-doped layer on single-crystal diamond that has undergone standard cleaning processes. Using a high-purity boron sheet (99.99% purity) formed by hot-pressing and sintering high-purity boron powder as a solid-state boron source, and based on a microwave plasma chemical vapor deposition (MPCVD) system, high-mobility heavy boron doping of single-crystal diamond is achieved by controlling the growth parameters.
[0016] Hydrogen plasma contacts and etches the surface of a boron sheet, causing boron atoms to detach from the surface and enter the plasma to participate in the diamond synthesis reaction, thus achieving the goal of introducing boron atoms into the diamond. Compared to the stepwise decomposition mechanism of boron-containing gases, the release of boron atoms from the boron sheet surface is easier and the boron reactants are purer. Furthermore, solid boron is closer to the diamond substrate, making it easier for boron atoms to diffuse to the diamond surface in the plasma, allowing for easy heavy doping. In-situ monitoring results from optical emission spectroscopy (OES) show that carbon atoms provided by methane promote the release of boron atoms from the solid boron sheet, accelerating the release and making high-concentration boron doping possible. Simultaneously, the absence of boron-containing gases ensures experimental safety and the high quality of the boron-doped diamond. The boron-doped single-crystal diamond prepared using this growth method is of excellent quality and meets the requirements for electronic device fabrication.
[0017] This invention employs microwave plasma chemical vapor deposition, using a solid boron sheet as the boron source. The carbon atoms provided by methane promote the release of boron atoms from the solid boron sheet, effectively facilitating the entry of doped atoms into the diamond lattice and achieving the preparation of high-quality, high-mobility doped single-crystal diamond. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the sample setup for the method of growing highly mobile, heavily doped single-crystal diamond using a solid boron source according to the present invention.
[0019] Figure 2 This is an actual internal view of the chamber used to grow highly mobile, heavily doped single-crystal diamond in Example 1;
[0020] Figure 3 This is a Van der Burglar schematic diagram of the Hall test used in the embodiment;
[0021] Figure 4 The Raman spectrum of the heavily doped single-crystal diamond sample grown in Example 2;
[0022] Figure 5 The graph shows a comparison of the mobility of boron-doped diamond prepared in Example 1 with that of samples in the literature. In the graph, ● represents the literature on Hole mobility in boron-doped diamond for power device applications, ■ represents the literature on High hole mobility in boron-doped diamond for power device applications, ▼ represents the literature on Properties of boron-doped epitaxial diamond layers grown on (110) oriented single crystal substrates, and ★ represents the literature on Properties of near-colourlesslightly boron-doped CVD diamond.
[0023] Figure 6 The image shows the optical emission spectrum (OES) during the growth process of Example 1. Detailed Implementation
[0024] Specific Implementation Method 1: This implementation method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source is carried out according to the following steps:
[0025] Step 1: Diamond leveling treatment:
[0026] The surface of a single-crystal diamond substrate is polished to obtain a polished diamond substrate.
[0027] Step 2, Surface Cleaning:
[0028] The polished diamond substrate was placed in a strong oxidizing mixed acid for high-temperature heating treatment, then immersed in plasma water for heating treatment, and ultrasonically cleaned to obtain a diamond substrate with oxygen terminals.
[0029] Step 3, Doping Growth:
[0030] In the cavity of a microwave plasma chemical vapor deposition apparatus, a single-crystal diamond substrate with oxygen terminals is placed on a solid boron sheet, which is then placed on a molybdenum support. A mixture of hydrogen and methane is introduced, with the hydrogen flow rate controlled at 100 sccm to 500 sccm, the methane concentration at 0.5% to 10%, the diamond substrate temperature at 700℃ to 1100℃, and the solid boron sheet temperature at 600℃ to 1200℃. A boron-doped diamond film is grown on the surface of the diamond substrate, resulting in a substrate with a boron-doped diamond film.
[0031] Step 4: Clean the surface again:
[0032] The substrate on which boron-doped diamond films are grown is placed in a strong oxidizing mixed acid for high-temperature heating treatment, then immersed in plasma water for heating treatment, and ultrasonically cleaned, thus completing the method of growing high-migration heavily doped single-crystal diamond using a solid boron source.
[0033] In step three of this embodiment, before growing the boron-doped diamond film, the sample can be pre-treated with hydrogen plasma for 5-30 minutes, with the hydrogen flow rate controlled at 100-500 sccm during etching.
[0034] This embodiment employs microwave plasma chemical vapor deposition, using a solid boron sheet as the boron doping source instead of a gaseous or liquid boron source. A Hall effect meter is used to characterize the boron carrier concentration and mobility in diamond, and Raman laser spectroscopy is used to characterize the crystal quality of diamond. High-concentration doping is achieved while maintaining good diamond crystal quality.
[0035] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the strong oxidizing mixed acid mentioned in step two is a mixture of concentrated sulfuric acid with a mass concentration of 98% and concentrated nitric acid with a mass concentration of 67% in a volume ratio of 3:1.
[0036] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the high-temperature heating treatment in step 2 is performed at a temperature of 230~350℃ for 2.0~2.5 hours.
[0037] Specific Implementation Method Four: This implementation method differs from one of the specific implementation methods one to three in that the solid boron sheet in step three is made by hot pressing and sintering boron powder.
[0038] Specific Implementation Method 5: This implementation method differs from Specific Implementation Method 4 in that the boron powder is produced by hot pressing and sintering, with the sintering temperature controlled at 1700℃, the pressure at 15MPa, and the sintering time at 2~3h.
[0039] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that, in step three, during the growth of a boron-doped diamond thin film on the diamond substrate, the pressure inside the cavity is controlled to be 50 mbar to 300 mbar, and the microwave power is 1000 W to 4000 W.
[0040] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the time for growing the boron-doped diamond film in step three is controlled to be 2h~6h.
[0041] The thickness of the boron-doped diamond film obtained in this embodiment is 4 μm to 10 μm.
[0042] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the volume concentration of methane is controlled to be 1.5% to 3.5% during the growth of boron-doped diamond thin films on the diamond substrate surface in step three.
[0043] Since the carbon atoms provided by methane promote the release of boron atoms from the solid boron sheet, this embodiment optimizes the volume concentration of methane during the growth of boron-doped diamond films.
[0044] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that, in step three, the hydrogen flow rate is controlled at 350 sccm to 450 sccm, the methane volume concentration is 2% to 4%, the diamond substrate temperature is 850℃ to 950℃, the solid boron sheet temperature is 900℃ to 1100℃, the cavity pressure is 70 mbar to 80 mbar, and a boron-doped diamond film is grown on the surface of the diamond substrate.
[0045] This embodiment uses a high-flow-rate growth gas, which accelerates the internal exchange frequency and enhances the internal fluidity of the plasma, thereby enhancing the etching of the high-purity boron sheet and exciting more boron elements on the surface.
[0046] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One through Nine in that the boron concentration in the boron-doped diamond film grown in step three is 10. 20 cm -3 ~10 21 cm -3 .
[0047] Specific Implementation Method Eleven: This implementation method differs from Specific Implementation Methods One through Ten in that, in step four, the immersion in plasma water at a temperature of 75-85°C for heating treatment for 30-50 minutes is performed.
[0048] Example 1: This example describes a method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source, implemented according to the following steps:
[0049] Step 1: Diamond leveling treatment:
[0050] The surface of a single-crystal diamond substrate is polished to obtain a polished diamond substrate.
[0051] Step 2, Surface Cleaning:
[0052] The polished diamond substrate was placed in a strong oxidizing mixed acid and heated at 230°C for 0.5 hours, and then heated at 350°C for another 1.5 hours. The strong oxidizing mixed acid was a mixture of concentrated sulfuric acid with a mass concentration of 98% and concentrated nitric acid with a mass concentration of 67% in a volume ratio of 3:1. The substrate was then immersed in plasma water at 85°C for 0.5 hours and ultrasonically cleaned to obtain a diamond substrate with oxygen terminals.
[0053] Step 3, Doping Growth:
[0054] In the cavity of a microwave plasma chemical vapor deposition apparatus, a diamond substrate with oxygen terminals is placed on a solid boron sheet, which is then placed on a molybdenum support. Hydrogen gas is introduced, and pre-etching is performed for 10 minutes under the following conditions: pressure of 6 kPa, microwave power of 1.2 kW, hydrogen flow rate of 200 sccm, and diamond substrate temperature of 850 °C.
[0055] Then, a mixture of hydrogen and methane was introduced, and the hydrogen flow rate was controlled at 196 sccm, the methane flow rate at 4 sccm, the diamond substrate temperature at 850℃, and the boron-doped diamond film was grown on the diamond substrate surface for 2 hours under the conditions of solid boron sheet temperature at 930℃, pressure at 60 mbar, and microwave power at 1200 W, to obtain a substrate with boron-doped diamond film grown on it.
[0056] Step 4: Clean the surface again:
[0057] The substrate with boron-doped diamond film was placed in a strong oxidizing mixed acid for high-temperature heating treatment. It was first heated at 230°C for 0.5 h, and then heated at 350°C for 1.5 h. It was then immersed in plasma water at 85°C for 0.5 h. The substrate was then ultrasonically cleaned for 15 min each with plasma water, anhydrous ethanol, and acetone in sequence. This completed the method of growing high-migration heavily doped single crystal diamond using a solid boron source.
[0058] In this embodiment, Raman laser spectroscopy is used to characterize the crystal quality of the diamond sample, obtain the Raman spectrum of the sample, and extract information such as the full width at half maximum (FWHM).
[0059] Based on the van der Berg principle, four symmetrical electrodes (such as...) are fabricated on the surface of the diamond sample. Figure 3 As shown in the figure, the conductivity of diamond was tested using an HMS-7000 Hall effect analyzer under a standard testing environment of 300K. Based on the van der Berg principle, four symmetrical electrodes were fabricated on the surface of the diamond sample. The HMS-7000 Hall effect analyzer was used to test the conductivity of the diamond, obtaining the sample's carrier concentration, carrier mobility, resistivity, and doping concentration. The carrier concentration of the boron-doped diamond film sample was 9.055 × 10⁻⁶. 18 cm -3 The carrier mobility is 83.82 cm⁻¹ 2 / Vs, resistivity 8.24×10 -3 The sheet resistance is 2.75 Ω / □. Since the boron doping concentration in diamond is difficult to completely ionize at room temperature, the calculated doping concentration of diamond is 3.99 × 10⁻⁶. 20 cm -3 .
[0060] Example 2: This example demonstrates a method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source, implemented according to the following steps:
[0061] Step 1: Diamond leveling treatment:
[0062] The surface of a single-crystal diamond substrate is polished to obtain a polished diamond substrate.
[0063] Step 2, Surface Cleaning:
[0064] The polished diamond substrate was placed in a strong oxidizing mixed acid and heated at 230°C for 0.5 hours, and then heated at 350°C for another 1.5 hours. The strong oxidizing mixed acid was a mixture of concentrated sulfuric acid with a mass concentration of 98% and concentrated nitric acid with a mass concentration of 67% in a volume ratio of 3:1. The substrate was then immersed in plasma water at 85°C for 0.5 hours and ultrasonically cleaned to obtain a diamond substrate with oxygen terminals.
[0065] Step 3, Doping Growth:
[0066] In the cavity of a microwave plasma chemical vapor deposition apparatus, a diamond substrate with oxygen terminals is placed on a solid boron sheet, which is then placed on a molybdenum support. Hydrogen gas is introduced, and pre-etching is performed for 10 minutes under the following conditions: pressure of 6 kPa, microwave power of 1.2 kW, hydrogen flow rate of 200 sccm, and diamond substrate temperature of 850 °C.
[0067] Then, a mixture of hydrogen and methane was introduced, and the hydrogen flow rate was controlled at 392 sccm, the methane flow rate at 8 sccm, the diamond substrate temperature at 875℃, and the boron-doped diamond film was grown on the diamond substrate surface for 6 hours under the conditions of solid boron sheet temperature at 950℃, pressure at 75 mbar, and microwave power at 1750 W, to obtain a substrate with boron-doped diamond film grown on it.
[0068] Step 4: Clean the surface again:
[0069] The substrate with boron-doped diamond film was placed in a strong oxidizing mixed acid for high-temperature heating treatment. It was first heated at 230°C for 0.5 h, and then heated at 350°C for 1.5 h. It was then immersed in plasma water at 85°C for 0.5 h. The substrate was then ultrasonically cleaned for 15 min each with plasma water, anhydrous ethanol, and acetone in sequence. This completed the method of growing high-migration heavily doped single crystal diamond using a solid boron source.
[0070] This embodiment uses Raman laser spectroscopy to characterize the crystal quality of a diamond sample, obtain the Raman spectrum of the sample, and extract information such as the full width at half maximum (FWHM). Figure 4 It can be seen that the crystal quality of the diamond-doped sample is excellent.
[0071] Based on the van der Berg principle, four symmetrical electrodes (such as...) are fabricated on the surface of the diamond sample. Figure 3 As shown in the figure, the conductivity of diamond was tested using an HMS-7000 Hall effect analyzer under a standard testing environment of 300K. Based on the van der Berg principle, four symmetrical electrodes were fabricated on the surface of the diamond sample. The HMS-7000 Hall effect analyzer was used to test the conductivity of the diamond, obtaining the sample's carrier concentration, carrier mobility, resistivity, and doping concentration. The carrier concentration of the heavily doped single-crystal diamond sample prepared in this embodiment was 2.662 × 10⁻⁶. 19 cm -3 The carrier mobility is 90.52 cm⁻¹ 2 / Vs, resistivity 2.59×10 -3 The sheet resistance is 2.59 Ω / □. Since the boron doping concentration in diamond is difficult to completely ionize at room temperature, the calculated doping concentration of diamond is 6.103 × 10⁻⁶. 20 cm -3 .
[0072] Unlike Example 1, Example 2 uses a high-flow-rate gas for doping growth. The study found that the high-flow-rate growth gas accelerates the internal exchange frequency and enhances the internal fluidity of the plasma, thus strengthening the etching effect on the high-purity boron sheet. More boron is excited on the boron sheet surface, increasing the boron concentration in the plasma and consequently increasing the doping concentration. Furthermore, the high-flow-rate gas enhances internal plasma exchange and fluidity, increasing the surface etching rate. This results in strong etching of both inherent defects and defects generated during growth, improving the crystal quality of the doped sample and significantly enhancing the electrical properties of the doped diamond sample.
[0073] In summary, this invention provides a method for achieving high quality and high mobility in boron-doped diamond through solid-state doping, with the attached... Figure 5 It is evident that their mobilities have all reached the highest known values for the same doping concentration. The realization of high-quality, high-mobility boron-doped diamond is of great significance for the development of diamond power semiconductor devices. This demonstrates that high-concentration boron-doped diamond can be grown using solid-state boron wafers while maintaining good crystal quality. This provides a new approach for the growth of heavily boron-doped diamond and offers technical support for the design and development of boron-doped diamond power devices.
[0074] This invention uses high-purity solid boron sheets (99.99% purity) as the boron source to achieve high-quality, high-mobility, and high-boron-doped single-crystal diamond growth (the solid boron source is made by hot-pressing and sintering high-purity boron powder). This invention is of great significance to the development of diamond power devices.
[0075] Although the present invention has been described in detail through the above preferred embodiments, the above description should not be considered as a limitation of the present invention. Other solutions based on the same principle are also within the protection scope of the present invention. Modifications and substitutions of the present invention will be obvious to those skilled in the art after reading the above content. Therefore, the protection scope of the present invention should be defined by the appended claims.
Claims
1. A method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source, characterized in that... The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source is implemented according to the following steps: Step 1: Diamond leveling treatment: The surface of a single-crystal diamond substrate is polished to obtain a polished diamond substrate. Step 2, Surface Cleaning: The polished diamond substrate was placed in a strong oxidizing mixed acid for high-temperature heating treatment, then immersed in plasma water for heating treatment, and ultrasonically cleaned to obtain a diamond substrate with oxygen terminals. Step 3, Doping Growth: In the cavity of a microwave plasma chemical vapor deposition apparatus, a single-crystal diamond substrate with oxygen terminals is placed on a solid boron sheet, which is then placed on a molybdenum support. A mixture of hydrogen and methane is introduced, with the hydrogen flow rate controlled at 100 sccm to 500 sccm, the methane concentration at 0.5% to 10%, the diamond substrate temperature at 700℃ to 1100℃, and the solid boron sheet temperature at 600℃ to 1200℃. A boron-doped diamond film is grown on the surface of the diamond substrate, resulting in a substrate with a boron-doped diamond film. Step 4: Clean the surface again: The substrate on which boron-doped diamond films are grown is placed in a strong oxidizing mixed acid for high-temperature heating treatment, then immersed in plasma water for heating treatment, and ultrasonically cleaned, thus completing the method of growing high-migration heavily doped single-crystal diamond using a solid boron source.
2. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... The strong oxidizing mixed acid mentioned in step two is a mixture of concentrated sulfuric acid with a mass concentration of 98% and concentrated nitric acid with a mass concentration of 67% in a volume ratio of 3:
1.
3. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... The high-temperature heating treatment mentioned in step two is a heating treatment at a temperature of 230~350℃ for 2.0~2.5h.
4. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... In step three, the solid boron sheet is made by hot pressing and sintering boron powder.
5. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 4, characterized in that... Boron powder is produced by hot pressing and sintering, with the sintering temperature controlled at 1700℃, the pressure at 15MPa, and the sintering time at 2~3h.
6. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... In step three, during the growth of boron-doped diamond thin films on the diamond substrate, the pressure inside the cavity is controlled at 50 mbar to 300 mbar, and the microwave power is 1000 W to 4000 W.
7. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... In step three, the growth time of the boron-doped diamond film is controlled to be 2h~6h.
8. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... In step three, during the growth of boron-doped diamond thin films on the diamond substrate surface, the volume concentration of methane is controlled to be 1.5%~3.5%.
9. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... In step three, the hydrogen flow rate is controlled at 350 sccm~450 sccm, the methane volume concentration is 2%~4%, the diamond substrate temperature is 850℃~950℃, the solid boron sheet temperature is 900℃~1100℃, and the cavity pressure is 70mbar~80mbar, so that a boron-doped diamond film is grown on the diamond substrate surface.
10. The method for growing highly mobile, heavily doped single-crystal diamond using a solid-state boron source according to claim 1, characterized in that... The boron concentration in the boron-doped diamond film grown in step three is 10. 20 cm -3 ~10 21 cm -3 .