CO2气氛下高择优取向(110)光学级金刚石膜的制备OA

Diamond films prepared by conventional microwave plasma chemical vapor deposition(MPCVD)often face issues such as low growth rates,disordered grain orientations,and non-diamond phase defects,which limit further enhancement of their optical properties.This study introduces CO₂ as an auxiliary gas to deposit high-quality diamond films using the MPCVD method.Diamond film deposition is conducted by introducing different flow rates of CO₂,and the optical emission characteristics of the plasma under varying CO₂ flow rates are measured using optical emission spectroscopy(OES).The crystallinity quality,grain orientation,surface morphology,and growth rate of the diamond films are characterized by XRD,Raman,and SEM.The results indicate that adding a certain amount of CO₂(flow ratio of CO₂/CH₄=2/6)is conducive to obtaining diamond films with a high(110)preferred orientation(I₂₂₀/I₁₁₁=18.19).An excessively high CO₂/CH₄ flow ratio intensifies the etching effect of oxygen-containing groups,reducing the degree of preferential grain orientation.The addition of an appropriate amount of CO₂ significantly improves the crystalline quality of the diamond,with the full width at half maximum(FWHM)of the diamond characteristic peak decreasing from 12.68 cm-1 to 8.26 cm-1.Furthermore,the addition of a suitable amount of CO₂ promotes diamond growth to some extent.Under the optimized flow ratio condition of CO₂/CH₄=2/6,this study successfully prepares a high(110)orientation(I₂₂₀/I₁₁₁=18.19)diamond film with a growth rate of 4 μm/h.After polishing,the self-standing diamond film achieves a transmittance of 71％at the 10.6 μm wavelength.Its transmittance in the long-wave infrared band approaches the theoretical value,meeting the requirements for applications such as long-wave infrared optical windows and extreme ultraviolet lithography machine windows.