A detailed surface chemistry mechanism is proposed for chemical vapor deposition of diamond films, which extends the growthhyphen;byhyphen;methyl mechanism proposed by Harris to treat any CHmradical,m=0ndash;3, as a growth monomer. Numerical computations were performed in which the mechanism was coupled to a model for the boundary layer above the substrate, for conditions typical of diamond deposition in an atmospherichyphen;pressure thermal plasma. The predicted linear growth rate increases strongly as the boundary layer thickness dgr; is decreased, and the results indicate a strong dependence of the diamond growth chemistry on dgr;. For relatively thick boundary layers (modest velocities of the reactant jet) growth is dominated by CH3. For very thin boundary layers (high velocities) the model predicts that growth is dominated by C. For the transition region where C and CH3each contribute about 40percnt; to growth, CH2also contributes about 17percnt;. The carbon conversion efficiency is also predicted to peak in the transition region, and drops sharply for very thin boundary layers.
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