Microstructure evolution in diamond CVD: Computer simulations of 111 surface site formation on a growing diamond-100 surface

A Monte Carlo simulation strategy was used to explore the kinetics and mech anisms of 111-surface site formation on a growing diamond-100 surface. The starting point of the simulations was a 30 x 30 carbon atom array with the structure of an ideally reconstructed, Diamond-(100)-(2 x 1) surface. The g rowth mechanism included 69 reactions relevant to diamond growth from CH3, H, and H-2. Several of the growth steps involved migration of C-1-containin g fragments across a diamond surface. The simulations were run for growth c onditions similar to those found in hot filament and microwave plasma diamo nd chemical vapor deposition (CVD) reactors. The temperature and gas-phase composition were varied to investigate the dependence of 111-surface site f ormation on growth conditions. The extent of 111-surface site formation was inferred from the height distributions of films that had been grown to mea n heights of 10 carbon monolayers. Results of the simulations imply that, f or typical hot filament and microwave plasma conditions, 111-surface site f ormation increases with growth temperature, decreases with H-atom concentra tion, and is relatively independent of methyl concentration. Much of the te mperature and composition dependence vanishes when reactions allowing for c arbon surface migration are prohibited. It is concluded that surface migrat ion plays an important role in microstructure development in diamond CVD.