High-conductivity N-type diamond epitaxially grown based on boron-phosphorus-nitrogen co-doping technology and preparation method of high-conductivity N-type diamond

Abstract

The invention discloses a high-conductivity N-type diamond epitaxially grown based on a boron-phosphorus-nitrogen co-doping technology and a preparation method of the high-conductivity N-type diamond, and relates to a growth method of a novel N-type diamond. According to the method, ammonia gas, borane and phosphorane are used as doping gas sources, the diamond is prepared on the diamond substrate by adopting a microwave plasma chemical vapor deposition (MPCVD) method, the activation energy of phosphorus atoms is reduced by utilizing a boron-phosphorus-nitrogen co-doping technology, and epitaxial growth of the N-type diamond is realized. By means of the boron-phosphorus-nitrogen co-doping technology, the phosphorus atom activation energy is reduced, the carrier concentration of the N-type diamond is improved, meanwhile, the growth cost of the N-type diamond is reduced, and an efficient and reliable novel method is provided for preparing the N-type diamond.

Description

Technical Field

[0001] This invention relates to a highly conductive N-type diamond epitaxially grown on a single-crystal diamond substrate using boron, phosphorus, and nitrogen co-doping technology, and to a method thereof, belonging to the field of diamond growth technology. Background Technology

[0002] Diamond, the hardest natural material on Earth, possesses many unique physical and chemical properties, making it a promising candidate for applications in numerous high-tech fields. Its hardness (10 Mohs) and extremely high thermal conductivity (approximately 2200 W / m·K) make it an ideal heat dissipation material for high-power electronic devices. Furthermore, diamond's extremely wide bandgap (5.5 eV) provides significant advantages for its application in high-temperature and high-power semiconductor devices. Due to its very low dielectric constant (5.7) and high electron mobility, diamond materials have also attracted considerable attention in fields such as radio frequency devices, quantum computing, and photodetectors. However, because of its large bandgap, intrinsic single-crystal diamond behaves as an insulator; therefore, achieving P-type and N-type doping of diamond is crucial for the research of diamond semiconductor devices. Currently, P-type doping of diamond can be achieved relatively stably. However, for N-type doping, using only phosphorus has disadvantages such as deep energy levels, large ionization energy, and poor repeatability. This results in low carrier concentration and mobility, making it difficult to meet the resistivity requirements of devices and affecting the electrical performance of N-type diamond.

[0003] The boron-phosphorus-nitrogen co-doping technology of this invention utilizes the small radius and easy lattice entry characteristics of boron atoms, along with the donor characteristics of phosphorus atoms. Boron doping alters the lattice strain, creating a favorable environment for phosphorus atoms to enter the lattice, thus improving the doping efficiency and concentration of phosphorus. B replaces C, and vacancies on the B edge are replaced by P, forming a shallow donor level BP complex. The presence of N promotes vacancy generation, resulting in sufficient BP complexes to obtain N-type diamond with high carrier concentration, synergistically improving the conductivity of N-type diamond. Therefore, using boron-phosphorus-nitrogen co-doping technology and epitaxial growth of diamond using MPCVD equipment, N-type diamond can be grown. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method for epitaxially growing highly conductive N-type diamond on a single-crystal diamond substrate using boron-phosphorus-nitrogen co-doping technology, thereby achieving the growth of N-type diamond and enabling it to possess high carrier concentration and mobility.

[0005] The technical solution adopted in this invention is as follows: A highly conductive N-type diamond epitaxially grown using boron-phosphorus-nitrogen co-doping technology is disclosed. The diamond is prepared on a single-crystal diamond substrate using a boron-phosphorus-nitrogen mixed gas as the dopant gas source and microwave plasma chemical vapor deposition (MPCVD). The boron-phosphorus-nitrogen co-doping technology is utilized to reduce the activation energy of phosphorus atoms, thereby achieving the growth of N-type diamond. The carrier concentration of the N-type diamond is 10-1. 20 cm -3 On the order of magnitude, with a resistivity of 10 −1 On the order of Ω·cm.

[0006] In the above technical solution, the boron-phosphorus-nitrogen source mixed gas includes borane (BH3), phosphine (PH3), and ammonia (NH3), with a mixing ratio of 3:3:1 to 3:4.5:1.

[0007] Furthermore, the preparation of diamond using the MPCVD method specifically includes: using diamond as a substrate, placing it in an MPCVD reaction chamber, evacuating the chamber, and then introducing a mixed gas of hydrogen, carbon source gas, and boron, phosphorus, and nitrogen source gas to grow diamond.

[0008] Furthermore, the vacuuming is performed until the background vacuum level in the reaction chamber is not less than 1×10⁻⁶. -3 During the growth process, the input power of the microwave source is controlled within the range of 2~5kW, and the cavity gas pressure ranges from 50~200Torr.

[0009] Furthermore, the carbon source gas is methane; the flow rate ratio of the hydrogen:methane:boron-phosphorus-nitrogen source mixed gas is 30:2:1 ~38:2:1.

[0010] A method for preparing highly conductive N-type diamond epitaxially grown using boron-phosphorus-nitrogen co-doping technology, as described in any one of the methods, includes the following steps: 1) Use undoped single-crystal diamond as the substrate; 2) The substrate was ultrasonically cleaned using acetone, isopropanol, ethanol, and deionized water; 3) Place the cleaned single-crystal diamond substrate into the MPCVD equipment chamber and evacuate to a background vacuum level of not less than 1×10⁻⁶. -3 Torr, after vacuuming, introduces a mixture of hydrogen, carbon source gas and boron phosphorus nitrogen source gas to grow diamond. During the growth stage, the microwave source input power is maintained at 2~5kW and the cavity gas pressure range is 50~200Torr. 5) After growth is complete, highly conductive N-type diamond is obtained on an undoped single-crystal diamond substrate.

[0011] Furthermore, the carbon source gas is methane; the boron-phosphorus-nitrogen source mixture includes borane, phosphine, and ammonia.

[0012] Furthermore, during the diamond growth process involving the introduction of a mixture of hydrogen, carbon source gas, and boron, phosphorus, and nitrogen source gas, the hydrogen gas flow rate is 700-990 sccm, the methane gas flow rate is 30 sccm, and the mixed gas flow rate of borane, phosphine, and ammonia is 40 sccm.

[0013] The beneficial effects of this invention compared to the prior art are: Traditional N-type diamond uses phosphorus atoms as dopants. However, phosphorus atoms have drawbacks such as deep energy levels, high ionization energy, and poor repeatability. This results in low carrier concentration and mobility in the grown N-type diamond, making it difficult to meet device requirements in terms of resistivity, thus affecting its electrical performance and limiting its application in electronic devices. This invention presents a method for epitaxially growing highly conductive N-type diamond based on boron-phosphorus-nitrogen co-doping technology. Based on the co-doping mechanism of boron, phosphorus, and nitrogen atoms, this invention innovates the growth method of N-type diamond. It mainly utilizes a boron-phosphorus-nitrogen mixed gas as the dopant gas source and employs MPCVD equipment for epitaxial growth, achieving the epitaxial growth of N-type diamond on a diamond substrate. Unlike using phosphorus atoms alone as dopants, this method uses boron, phosphorus, and nitrogen atoms simultaneously as dopants. B replaces C, and nearby vacancies are replaced by P, forming a shallow donor-level BP complex. The presence of N promotes vacancy generation, resulting in sufficient BP complexes. This leads to higher carrier concentration and mobility in the grown N-type diamond, with carrier concentrations reaching up to 10-1. 20 cm -3 It also has excellent repeatability, which greatly enhances the application potential of N-type diamond in the field of electronic devices. Attached Figure Description

[0014] Figure 1 The Raman spectrum of N-type diamond epitaxially grown using boron-phosphorus-nitrogen co-doping technology, obtained by the method in Example 1, is shown in the test range of 100 cm⁻¹. -1 Up to 2500cm -1 Raman Peak is located at 1333.2 cm. -1 The location indicates that the N-type diamond obtained by the method in Example 1 is a single crystal; Figure 2 The Raman spectrum of N-type diamond epitaxially grown using boron-phosphorus-nitrogen co-doping technology, obtained using the method in Example 2, is measured over a range of 100 cm⁻¹. -1 Up to 2500cm -1 Raman Peak is located at 1332.4 cm. -1 The location indicates that the N-type diamond obtained by the method in Example 2 is a single crystal; Figure 3The SIMS test results for N-type diamond epitaxially grown using the boron-phosphorus-nitrogen co-doping technique obtained in Example 2 are shown below. The test depth is 2 μm. According to the test results, the boron atom concentration in this N-type diamond sample is 1.3 × 10⁻⁶. 19 cm -3 The phosphorus atom concentration is 3.6 × 10⁻⁶. 17 cm -3 The nitrogen atom concentration is 3.1 × 10⁻⁶. 16 cm -3 ; Figure 4 This is a schematic diagram of the N-type diamond structure epitaxially grown using boron-phosphorus-nitrogen co-doping technology, prepared according to the method in Example 2. Figure 5 The image shows an N-type diamond epitaxially grown using the boron-phosphorus-nitrogen co-doping technique prepared according to the method in Example 2. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0016] Reference Figure 4 This invention discloses an N-type diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology. A boron-phosphorus-nitrogen source mixed gas is used as the dopant gas source, and N-type diamond is prepared on the diamond substrate using microwave plasma chemical vapor deposition (MPCVD). The boron-phosphorus-nitrogen co-doping technology is utilized to improve the doping efficiency and concentration of phosphorus, thereby achieving the growth of N-type diamond. When the MPCVD growth conditions are varied, the Raman peak positions in the Raman spectra measured in Examples 1 and 2 do not show significant deviations (e.g., ...). Figure 1 and 2 The present invention discloses an N-type diamond epitaxially grown on a diamond substrate using boron, phosphorus, and nitrogen co-doping technology, which can effectively provide a low-cost, high-quality growth technology for N-type diamond growth, and promote the development of diamond growth technology and diamond semiconductors. Example 1:

[0017] 1) Take an undoped single crystal diamond with a size of 7 mm × 7 mm as a substrate, and polish the growth surface to ensure that the growth surface is smooth and flat; 2) The substrate was sequentially immersed in acetone, isopropanol, ethanol and deionized water for ultrasonic cleaning of the substrate surface. Each solvent was used for 10 min to remove organic impurities attached to the surface and then dried with N2. 3) Place the cleaned diamond substrate into the MPCVD equipment chamber and evacuate the chamber to 10°C. -3After the Torr is introduced, hydrogen, carbon source gas (methane), and a mixture of boron, phosphorus, and nitrogen source gases (a mixture of borane, phosphine, and ammonia) are introduced. 4) During the growth stage, maintain the microwave source input power at 4 kW, the cavity gas pressure at 150 Torr, the growth temperature at 970℃, the hydrogen gas flow rate at 780 sccm, the methane gas flow rate at 30 sccm, and the mixed gas flow rate of borane, phosphine and ammonia at 40 sccm. Specifically, the flow rates are: borane 15 sccm, phosphine 20 sccm, and ammonia 5 sccm.

[0018] The diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology, as shown in Table 1, exhibits a Hall coefficient of -2.61 cm⁻¹. 3 ·C -1 The carrier concentration is 5.77 × 10⁻⁶. 20 cm -3 The resistivity is 2.66 × 10⁻⁶. −1 The Hall coefficient is Ω·cm. Based on the Hall effect test data, it can be found that the diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology according to this invention is N-type diamond, and it has a high carrier concentration and low resistivity. As shown in Table 1, the Hall coefficient of N-type diamond obtained using only boron-phosphorus co-doping technology without ammonia is -2.95 cm⁻¹. 3 ·C -1 The carrier concentration is 6.23 × 10⁻⁶. 19 cm -3 The resistivity is 4.21. Compared to Example 1 obtained using boron-phosphorus-nitrogen co-doping technology, the carrier concentration decreased by an order of magnitude and the resistivity increased by an order of magnitude in Ω·cm. This demonstrates that boron-phosphorus-nitrogen co-doping technology can further increase the carrier concentration and reduce the resistivity of N-type diamond compared to boron-phosphorus co-doping technology without nitrogen atoms. An N-type diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology according to the present invention has the following Raman spectrum: Figure 1 As shown, at Raman shift = 1333.2 cm -1 A distinct peak appears at the specified location. Raman spectroscopy reveals that the N-type diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology, as described in this invention, is a single-crystal diamond. Example 2:

[0019] 1) Take an undoped single crystal diamond with a size of 8 mm × 8 mm as a substrate, and polish the growth surface to ensure that the growth surface is smooth and flat; 2) The substrate was sequentially immersed in acetone, isopropanol, ethanol and deionized water for ultrasonic cleaning of the substrate surface. Each solvent was used for 10 min to remove organic impurities attached to the surface and then dried with N2. 3) Place the cleaned diamond substrate into the MPCVD equipment chamber and evacuate the chamber to 10°C. -3 After the Torr is introduced, hydrogen, carbon source gas (methane), and a mixture of boron, phosphorus, and nitrogen source gases (a mixture of borane, phosphine, and ammonia) are introduced. 4) During the growth stage, maintain the microwave source input power at 4 kW, the cavity gas pressure at 120 Torr, the growth temperature at 930℃, the hydrogen gas flow rate at 780 sccm, the methane gas flow rate at 30 sccm, and the mixed gas flow rate of borane, phosphine and ammonia at 40 sccm. Specifically, the flow rates are: borane 15 sccm, phosphine 20 sccm, and ammonia 5 sccm.

[0020] The N-type diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology obtained in this example has a Hall coefficient of -3.05 cm⁻¹, as shown in Table 1. 3 ·C -1 The carrier concentration is 2.91 × 10⁻⁶. 20 cm -3 The resistivity is 3.83 × 10⁻⁶. −1 Ω·cm. The N-type diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology obtained in this example has the following Raman spectrum: Figure 2 As shown, at Raman shift = 1332.4 cm -1 A distinct peak appears at this location. The SIMS test results for the N-type diamond epitaxially grown on a diamond substrate using boron-phosphorus-nitrogen co-doping technology obtained in this example are as follows: Figure 2 As shown, the boron atom concentration in this N-type diamond sample is 1.3 × 10⁻⁶. 19 cm -3 The phosphorus atom concentration is 3.6 × 10⁻⁶. 17 cm -3 The nitrogen atom concentration is 3.1 × 10⁻⁶. 16 cm -3 Compared to Example 1, after the treatment in step 4), i.e., after reducing the chamber pressure by 30 Torr and the growth temperature by 40°C during the growth stage, the carrier concentration of N-type diamond decreased from 5.77 × 10⁻⁶. 20 cm -3 It dropped to 2.91×10 20 cm -3 The resistivity is 2.66 × 10⁻⁶. −1 The Ω·cm increased to 3.83 × 10⁻⁶. −1Ω·cm, the Raman peak shifted 0.8 cm to the left. -1 It is evident that changing the air pressure and temperature conditions during diamond growth within a certain range does not affect the epitaxial growth of N-type diamond.

[0021] Table 1:

[0022] It is obvious that this invention is not limited to the specific embodiments described above. Those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of this invention. The exemplary embodiments were chosen and described to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various exemplary embodiments of the invention, as well as various choices and modifications. The scope of this invention is intended to be defined by the claims and their equivalents.

Claims

1. A highly conductive N-type diamond epitaxially grown using boron-phosphorus-nitrogen co-doping technology, characterized in that... Diamond was prepared on a diamond substrate using a boron-phosphorus-nitrogen mixed gas as the dopant gas source and microwave plasma chemical vapor deposition (MPCVD) to achieve epitaxial growth of N-type diamond. The carrier concentration of the N-type diamond was 10. 20 cm -3 On the order of magnitude, with a resistivity of 10 −1 On the order of Ω·cm.

2. The highly conductive N-type diamond epitaxially grown based on boron-phosphorus-nitrogen co-doping technology according to claim 1, characterized in that, The boron-phosphorus-nitrogen source mixed gas includes borane (BH3), phosphine (PH3), and ammonia (NH3) in a volume ratio of 3:3:1 to 3:4.5:

1.

3. The highly conductive N-type diamond epitaxially grown based on boron-phosphorus-nitrogen co-doping technology according to claim 1, characterized in that, The preparation of diamond on a diamond substrate using the MPCVD method specifically includes: using diamond as a substrate, placing it in an MPCVD reaction chamber, evacuating the chamber, and then introducing a mixed gas of hydrogen, carbon source gas, and boron, phosphorus, and nitrogen source gas to grow diamond.

4. The highly conductive N-type diamond epitaxially grown based on boron-phosphorus-nitrogen co-doping technology according to claim 3, characterized in that, The vacuuming process is to ensure that the background vacuum level in the reaction chamber is not less than 1×10⁻⁶. -3 During the growth process, the input power of the microwave source is controlled within the range of 2~5kW, and the cavity gas pressure ranges from 50~200Torr.

5. A highly conductive N-type diamond epitaxially grown based on boron, phosphorus, and nitrogen co-doping technology according to claim 3, characterized in that, The carbon source gas is methane; the flow rate ratio of the hydrogen:methane:boron-phosphorus-nitrogen source mixed gas is 30:2:1 ~38:2:

1.

6. A method for preparing highly conductive N-type diamond epitaxially grown using boron-phosphorus-nitrogen co-doping technology as described in any one of claims 1-5, characterized in that, Includes the following steps: 1) Use undoped single-crystal diamond as the substrate; 2) The substrate was ultrasonically cleaned using acetone, isopropanol, ethanol, and deionized water; 3) Place the cleaned single-crystal diamond substrate into the MPCVD equipment chamber and evacuate to a background vacuum level of not less than 1×10⁻⁶. -3 Torr, after vacuuming, introduces a mixture of hydrogen, carbon source gas and boron phosphorus nitrogen source gas to grow diamond. During the growth stage, the microwave source input power is maintained at 2~5kW and the cavity gas pressure range is 50~200Torr. 4) After growth is complete, highly conductive N-type diamond is obtained on an undoped single-crystal diamond substrate.

7. The preparation method according to claim 6, characterized in that, The carbon source gas is methane; the boron-phosphorus-nitrogen source mixture includes borane, phosphine, and ammonia.

8. The preparation method according to claim 7, characterized in that, During the diamond growth process, the flow rate of hydrogen gas, carbon source gas, and boron-phosphorus-nitrogen source mixed gas is 700-990 sccm, the flow rate of methane gas is 30 sccm, and the flow rate of the mixed gas of borane, phosphine, and ammonia is 40 sccm.

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