An extensive search was made for diffusion and decomposition pathways for SiH3, SiH2 and SiH, by using combined ab initio metadynamics simulations and optimization of minimum-energy reaction paths. It was found that, on the clean surface, SiH3 underwent step-wise decomposition into Si and H adatoms via: SiH3 → SiH2 + H → SiH + 2H → Si + 3H. The overall reaction barrier was of the order of 0.8eV; consistent with the model deduced from secondary ion mass spectroscopy data. The lifetime of SiH3 at room temperature, calculated using transition-state theory in the harmonic approximation, was in agreement with experiment. The lifetime of SiH2 was similar to that of SiH3. Possible trap states for SiH2 were proposed, based upon energetics and upon comparisons of calculated scanning tunnelling microscopic images with experimental data.

Ab initio Study of the Diffusion and Decomposition Pathways of SiHx Species on Si(100). M.Ceriotti, S.Cereda, F.Montalenti, L.Miglio, M.Bernasconi: Physical Review B, 2009, 79[16], 165437