Microcrystalline diamond growth in presence of argon in millimeter-wave plasma-assisted CVD reactor

The additions of argon and oxygen to H2–CH4 feed gas and high-electron-density plasma generated by the millimeter-wave power were used to deposit microcrystalline diamond films having high quality and high growth rate simultaneously. Microcrystalline diamond films were grown on silicon substrates with 60–90 mm diameter in the millimeter-wave plasma-assisted CVD reactor based on 10 kW gyrotron operating at a frequency of 30 GHz. The growth process and morphology of diamond films at wide variation of parameters (gas pressure, substrate temperature, microwave power, argon and oxygen concentrations in gas mixtures Ar–H2–CH4 and Ar–H2–CH4–O2) are investigated. For understanding of growth conditions the investigations of the plasma parameters (electron density and gas temperature) in novel CVD reactor are presented.