CH5 precursor mechanism for diamond growth

Abstract

Deposition rates of polycrystalline diamond films are investigated as a function of concentration of water vapor in a microwave chemical vapor deposition (CVD) apparatus. For CH4:H2 = 2%:98% gas composition the measured deposition rates are compared with mass spectroscopic data published in the literature and predictions suggested by the widely accepted methyl radical (CH3) diamond growth model. Our results do not confirm the CH3 model, but a good correlation is found between the concentration of CH 5+ radicals and the deposition rates of diamond. The main reaction paths leading to diamond deposition from CH 5+ are also presented.