A surface and a gas-phase mechanism for the description of growth on the diamond(100) surface in an oxy-acetylene torch reactor

A gas-phase and a surface mechanism were developed, suitable for multidimensional simulations of diamond oxy-acetylene torch reactors. The gas-phase mechanism was obtained by reducing a 48 species combustion chemistry mechanism to a 27 species mechanism with the aid of sensitivity analysis. The surface mechanism for growth on monocrystalline (100) surfaces developed, was based on literature quantum-mechanical calculations by Skokov et al. It consists of 67 elementary reaction steps and 41 species, and contains CH3 and C2H2 as gas-phase growth precursors and atomic hydrogen and oxygen to etch carbon from the surface. The gas-phase and surface chemistry models were tested in one-dimensional simulations, yielding dependencies of the growth rate on feed composition and surface temperature that are in qualitative agreement with the experiments. A more detailed study of the surface chemistry showed that, compared to CH3, acetylene contributes very little to diamond growth. Furthermore, molecular and atomic oxygen do not affect the diamond surface as much as atomic hydrogen because of their low concentrations