Gas flow effects in synthesis of diamond by hot-filament chemical vapor deposition

Hot-filament chemical vapor deposition was employed to study the effect of gas flow dynamics on diamond growth. The density and growth rate of diamond within the patterned region of copper and silicon substrates was found to be twice as large as compared with that on a flat (unpatterned) surface. The density of diamond nucleation increased on patterned silicon and copper substrates with an increase in the methane concentration from 1.0% to 1.5% in the gas mixture of methane and hydrogen (CH₄ + H₂). Selective growth of diamond was achieved without using diamond seed or paste, or scratching the patterned silicon substate. About 90% diamond coverage and a continuous diamond film (75 μm) were achieved on the square-patterned silicon and copper substrates, respectively, at a methane concentration of 1.5%. The growth of diamond within the wells was discussed on the basis of gas flow dynamics. The present analysis is consistent with available theoretical models.