MOLECULAR-DYNAMICS SIMULATIONS OF METHYL-RADICAL DEPOSITION ON DIAMOND (100) SURFACES

We have performed molecular-dynamics simulations using realistic many-body semiclassical potentials for hydrocarbon interactions to investigate the deposition dynamics of hyperthermal CH3 on diamond (100) surfaces. The adsorption probability was studied as a function of different incident radical and substrate conditions. Relevant energy exchange processes between incident molecules and the substrate were also analyzed. Three types of events were observed in the simulations: (i) adsorption events where CH3 bonds onto a surface radical ''site,'' (ii) reflection events where CH3 backscatters to the gas phase, and (iii) surface-hydrogen knock-out events at high incident CH3 energy. The adsorption probability was found to be higher for normal incidence to the surface, and to increase for larger incident kinetic energies. The adsorption efficiency is not sensitive to surface H coverage except at lower CH3 energies. No chemisorption of the radical on a surface that is fully hydrogen terminated is observed, indicating that a radical site is needed for the CH3 to bind on the surface. Significant energy transfer through collision is observed.