Theoretical search for atomic-like states of silicon at the surface of thermally grown SiO2 films on silicon surfaces

The existence of atomic-silicon cryptates in siloxanic networks has been studied theoretically via standard density functional theory calculations. Mimicking with model molecules the candidate sites to host atomic silicon, we found that stationary states are impossible in highly reticulated siloxanic networks; metastable adducts can only be formed at their external surfaces or in regions where the siloxanic network is subjected to weak steric constraints. This analysis suggests that the atomic silicon injected into the oxide during thermal oxidation of silicon by O2 may be trapped as a metastable adduct at the oxide surface.