Quantitative estimate of H abstraction by thermal SiH3 on hydrogenated Si(001)(2x1)

A very high probability (similar to 60%) for H abstraction induced by SiH3 thermal impacts on the Si(001)(2x1) hydrogenated surface is reported, as a consequence of the Eley-Rideal mechanism by which a silane molecule is formed. The reaction probability is computed within a fully dynamical approach. After running a limited set of ab initio Car-Parrinello simulations to validate a suitable empirical potential, an actual probability for the mechanism was estimated by averaging over thousands of classical molecular dynamics simulations. The probability of H abstraction is shown to be quite constant in the typical experimental range for plasma-enhanced chemical vapor deposition. Very low evidence for insertion of the radical into surface Si-Si bonds is found.