Simulations of chemical vapor deposition diamond film growth using a kinetic Monte Carlo model

A one-dimensional kinetic Monte Carlo model has been developed to simulate the chemical vapor deposition (CVD) of a diamond (100) surface. The model considers adsorption, etching/desorption, lattice incorporation, and surface migration along and across the dimer rows. The reaction rates for these processes are re-evaluated in detail and their effect upon the predicted growth rates and morphology are described. We find that for standard CVD diamond conditions, etching of sp(3) carbon species from the growing surface is negligible. Surface migration occurs rapidly, but is mostly limited to CH2 species oscillating back and forth between two adjacent radical sites. Despite the average number of migration hops being in the thousands, the average surface diffusion length for a surface species-before it either adds to the diamond lattice or is removed back to the gas phase-is <2 sites. beta-scission helps to smooth the surface, but is only a relatively minor process removing <2% of adsorbed species. At low substrate temperature, migration is negligible with film growth being dominated by direct adsorption (Eley-Rideal) processes. The resulting films are rough and spiky, reminiscent of amorphous carbon. With increasing substrate temperature migration increases in significance until for temperatures >1000 K migration becomes the major process by which the surface becomes smoother. Langmuir-Hinshelwood processes are now the dominant growth mechanism, although 30% of growth still occurs via direct adsorption. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3437647]