Structure of ultrathin crystalline SiO2 films on Mo(112) -: art. no. 161307

The geometrical and electronic structures of a thin SiO2 film epitaxially grown on a Mo(112) substrate have been determined by first-principles density-functional theory calculations. beta-cristobalite, beta-tridymite, alpha-quartz, and beta-quartz phases were considered. The film grows initially with an OH-terminated beta-cristobalite structure which provides the strongest adhesion energy to the Mo substrate. High-temperature annealing results in a complete dehydroxylation and reconstruction of the top layer of the cristobalite film with the formation of two-membered silica rings. This accounts for a specific band at 795 cm(-1) observed in the Fourier transform infra-red (FTIR) spectrum of the annealed epilayer.