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CN-121992495-A - Method for preparing monocrystalline diamond by heteroepitaxy method

CN121992495ACN 121992495 ACN121992495 ACN 121992495ACN-121992495-A

Abstract

The invention provides a method for preparing monocrystalline diamond by a heteroepitaxy method, which belongs to the technical field of microwave plasma chemical vapor deposition and comprises the following steps of selecting a heterosubstrate and carrying out surface pretreatment; and primarily depositing a transition layer consisting of cellular diamond on the surface of the pretreated heterogeneous substrate, secondarily depositing diamond particles with single-crystal areas at the top on the surface of the obtained transition layer, wherein the deposition adopts a microwave plasma chemical vapor deposition technology. The invention realizes the high-speed preparation of the monocrystalline diamond by regulating and controlling the methane flow, the nitrogen flow and the deposition temperature in a sectional way. The method comprises the steps of depositing a transition layer composed of cellular diamond at high methane flow, low nitrogen flow and low temperature, and then increasing the nitrogen flow and the deposition temperature to increase the deposition rate, so that part of cellular diamond obtains longitudinal growth advantages, and finally diamond particles with single-crystal areas at the top are formed.

Inventors

  • AN KANG
  • LI LIJUN
  • XU GUANGYU
  • Rong wolong
  • LIU FENGBIN
  • ZHANG XUFANG
  • DOU ZHAOLIANG
  • YANG YE

Assignees

  • 北方工业大学

Dates

Publication Date
20260508
Application Date
20251224

Claims (10)

  1. 1. A method for preparing single crystal diamond by heteroepitaxy, comprising the steps of: s1, selecting a heterogeneous substrate and carrying out surface pretreatment; s2, firstly depositing a transition layer consisting of cellular diamond on the surface of the pretreated heterogeneous substrate; S3, secondarily depositing diamond particles with single-crystal areas at the tops on the surface of the transition layer obtained in the step S2; Wherein, step S2 and step S3 adopt microwave plasma chemical vapor deposition technology.
  2. 2. The method for preparing single crystal diamond by heteroepitaxy according to claim 1, wherein in step S1, the heterogeneous substrate is made of tungsten, copper, iron, molybdenum or silicon, the substrate is round, the thickness is 200 μm-1 mm, the diameter is 2-12 inches, and the surface pretreatment is to sequentially clean the surface of the substrate with alcohol and acetone.
  3. 3. The method of preparing single crystal diamond according to claim 1, wherein in step S2, the microwave frequency used for deposition is 2.45 GHz or 915 MHz, the initial deposition temperature is 600-850 ℃, the chamber pressure is 2-40 kPa, the methane flow is 3-8% of the hydrogen flow, and the nitrogen flow is 0.1-0.5% of the hydrogen flow.
  4. 4. The method of preparing single crystal diamond according to claim 1, wherein in step S3, the microwave frequency used for deposition is 2.45 GHz or 915 MHz, the secondary deposition temperature is 850-1100 ℃, the chamber pressure is 2-40 kPa, the methane flow is 3-8% of the hydrogen flow, and the nitrogen flow is 0.5-5% of the hydrogen flow.
  5. 5. A method of preparing single crystal diamond by heteroepitaxy according to claim 3 or 4, wherein step S2 and step S3 maintain the same microwave frequency; When the microwave frequency is 2.45 GHz, the microwave power is 1-15 kW, the hydrogen flow is 200-800 sccm, the deposition time of the transition layer in the step S2 is 20-60 h, and the deposition time in the step S3 is 80-240 h; when the microwave frequency is 915 MHz, the microwave power is 1-75 kW, the hydrogen flow is 1-10 slm, the deposition time of the transition layer in the step S2 is 20-30 h, and the deposition time in the step S3 is 150-200 h.
  6. 6. The method of preparing single crystal diamond by heteroepitaxy according to claim 1, wherein the temperature rising rate of the chamber is 500-1000 ℃ per hour at step S2 and switching from step S2 to step S3, and the chamber is cooled to room temperature at a rate of 50-200 ℃ per hour after the deposition of step S3 is completed.
  7. 7. A method of preparing single crystal diamond by heteroepitaxy as claimed in claim 1, wherein in step S2, the vertical height of the transition layer is in the range 100-300 μm.
  8. 8. A method of preparing single crystal diamond by heteroepitaxy as claimed in claim 1, wherein in step S3 the growth rate of diamond particles in the single crystal region on top is 5-15 μm/h and the vertical height of the diamond particles is greater than 1 mm.
  9. 9. The method for preparing single crystal diamond by heteroepitaxy according to claim 1, wherein the diamond particles with single crystal regions on top in step S3 have a growth parameter α being equal to or greater than 3.
  10. 10. Diamond particles prepared by the method according to any one of claims 1 to 9, wherein the top region of the diamond particles is single crystal diamond.

Description

Method for preparing monocrystalline diamond by heteroepitaxy method Technical Field The invention belongs to the technical field of microwave plasma chemical vapor deposition, and particularly relates to a method for preparing monocrystalline diamond by a heteroepitaxy method. Background The diamond has a series of excellent performances such as high hardness, high heat conductivity, high forbidden bandwidth, high optical transmittance and the like, so that the diamond has good application prospect in the fields such as ultra-precise machining, electronics, optical materials and the like. The current method for artificially synthesizing diamond monocrystal mainly comprises a high-temperature high-pressure method and a chemical vapor deposition method. The high temperature and high pressure method is to make the carbon source at the central high temperature and the seed crystal at the low temperature, and to utilize the temperature gradient generated in the axial direction to promote the diffusion of carbon atoms from the high temperature to the low temperature along the axial direction. The technology is developed for the first time in the United states in the last 70 th century, the diamond size and quality prepared by the method are greatly improved along with the continuous progress of the technology, but the high-temperature and high-pressure method is limited by high-pressure equipment, the prepared diamond monocrystal is smaller in size and easy to introduce some metal impurities, the synthetic quality of the diamond is reduced, the other synthetic method is a CVD method, the diamond can be decomposed into hydrocarbon active groups through high temperature by hydrogen and methane gas, the diamond is deposited on a substrate material under certain conditions, the size prepared by the method is theoretically unlimited, and the quality of the prepared monocrystal diamond is high. The CVD method generally adopts a homoepitaxy method, and because the substrate material is not single crystal diamond, there is a large lattice mismatch and a thermal expansion coefficient difference, which can cause the orientation of the growth surface of the diamond to be disordered, and is unfavorable for the synthesis of single crystal diamond. In addition, the substrate of the homoepitaxial method for preparing the monocrystalline diamond is monocrystalline diamond, so that the cost for preparing the monocrystalline diamond is increased, and the deposition rate of the homoepitaxial method is lower. Disclosure of Invention Aiming at the problems existing in the prior art that the monocrystalline diamond is prepared by adopting a homoepitaxy method, the monocrystalline diamond is prepared by adopting a heteroepitaxy method. The prepared single crystal diamond has high quality, can reduce the preparation cost and can improve the preparation efficiency. In order to achieve the above purpose, the technical scheme provided by the invention is as follows: A method for preparing single crystal diamond by heteroepitaxy, comprising the steps of: s1, selecting a heterogeneous substrate and carrying out surface pretreatment; s2, firstly depositing a transition layer consisting of cellular diamond on the surface of the pretreated heterogeneous substrate; S3, secondarily depositing diamond particles with single-crystal areas at the tops on the surface of the transition layer obtained in the step S2; Wherein, step S2 and step S3 adopt microwave plasma chemical vapor deposition technology. Optionally, in step S1, the material of the hetero-substrate is tungsten, copper, iron, molybdenum or silicon. The substrate is round, the thickness is 200 mu m-1 mm, the diameter is 2-12 inches, and compared with the preparation of single crystal diamond by a homoepitaxy method, the preparation cost can be reduced by using the heterogeneous substrate. The surface pretreatment of the substrate is sequentially cleaned by alcohol and acetone. Optionally, in step S2, the microwave frequency used for the deposition is 2.45 GHz or 915 MHz, the primary deposition temperature is 600-850 ℃, the chamber pressure is 2-40 kPa, the methane flow is 3-8% of the hydrogen flow, and the nitrogen flow is 0.1-0.5% of the hydrogen flow. Optionally, in step S3, the microwave frequency used for the deposition is 2.45 GHz or 915 MHz, the secondary deposition temperature is 850-1100 ℃, the chamber pressure is 2-40 kPa, the methane flow is 3-8% of the hydrogen flow, and the nitrogen flow is 0.5-5% of the hydrogen flow. Optionally, step S2 and step S3 maintain the same microwave frequency. When the microwave frequency is 2.45 GHz, the microwave power is 1-15 kW, the hydrogen flow is 200-800 sccm, the deposition time of the transition layer in the step S2 is 20-60 h, the deposition time in the step S3 is 80-240 h, when the microwave frequency is 915 MHz, the microwave power is 1-75 kW, the hydrogen flow is 1-10 slm, the deposition time of the transition layer in the step S2 is