Thermochemical and Kinetic Considerations in Diamond Growth

Abstract

Abstract : Considerations important to the modeling of the diamond growth process include the question of what surface structures may exist during the growth process and how these structures may be determine or be determined by the composition of the gas phase adjacent to the surface. The simple truncated lattice structures of the three low index surfaces are reviewed and the steric problem inherent to the hydrogenated unreconstructed (100) surface is illustrated. It is proposed that the zone axis is the highest growth rate direction as this is the dominant texture seen in many experiments and that a model for diamond growth along this axis should therefore be of great interest. The assumptions inherent in much modeling are illustrated through the calculation of the mole fraction product of surface reactive sites and the methyl radical. If a methyl radical mole fraction of 10(-3) to 10(-4) is assumed then the mole fraction of reactive sites at the diamond surface would have to be approximately 10(-4) to 10(-3). Included in these assumptions is that the rate limiting process is the addition of carbon at the growth surface, that the diamond surface can be treated in effect as a large hydrocarbon, and that the only reactions of importance are those that would also be observed for simple hydrocarbon species in the gas phase.