Adsorption of molecular SiO2 on a clean Si(1Â 0Â 0) surface

We have investigated the adsorption of molecular (gaseous) SiO2 on a clean Si(1 0 0) p(2 × 2) reconstructed surface using density functional theory based methods. The SiO2 molecule is found to be chemisorbed on various sites on the Si surface and the most energetically favourable structure is on top of the dimers. The minimum energy pathways for the various adsorption channels indicate that the reaction is barrierless in all cases. The corresponding vibrational spectrum is also calculated and the adsorbed molecules are, as expected, found to have red-shifted vibrational frequencies. The energetically favourable adsorption sites and adsorption energies are comparable to the results found for SiO.