Uncoupling crystal-growth and nucleation in the deposition of diamond from the gas-phase

Diamond deposits of well-separated particles have been obtained by the hot filament CVD technique on Si(100) wafers. Particle counting in SEM images and determination of their linear dimensions require a separate study of growth rates and of nucleation densities as a function of time, substrate temperature (500-degrees-C-950-degrees-C), gas phase composition (0.5-2% CH4 in H2), and total pressure (15-76 Torr). It is shown that recent models proposed for the growth process can successfully be applied if proper consideration is given to the high catalytic activity of the growing diamond surface for the heterogeneous recombination of gaseous H-atoms. This fast reaction controls the H-atom concentration at the surface and couples growth rates and nucleation densities via the gas phase.