Structure of thin SiO2 films grown on Mo„112..

Ultra-thin SiO2 films were prepared by evaporating Si onto a Mo~112! surface followed by oxidation and annealing up to 1200 K. The surface structure and film quality were investigated by low-energy electron diffraction ~LEED!, Auger spectroscopy ~AES!, and high-resolution electron energy loss spectroscopy ~HREELS!. A well-ordered, monolayer Mo(112)-c(232)-SiO2 structure was characterized by HREELS and shown to exhibit unique phonon features compared to bulk SiO2 . The phonon features are assigned to SiO-Mo rather than Si-O-Si species, and the surface structure determined to be Mo(112)-c(232)-@SiO4# where each of the four oxygen atoms bonds to the substrate Mo atoms.