X-ray photoelectron spectroscopic characterization of ultra-thin silicon oxide films on a Mo( 100) surface

Ultra-thin films of silicon oxides supported on a MoflOO) surface have been studied using X-ray photoelectron spectroscopy (XPS). The films were synthesized by evaporating Si onto the MO surface in oxygen ambient and were subsequently characterized using XPS with respect to the chemical states of silicon and the composition of the film. It has been found that the silicon oxide, prepared at room temperature with a silicon deposition rate of N 1.2 A/min and an oxygen pressure of 2 x lo-’ Torr, consisted of predominantly silicon dioxide with a small fraction of suboxides. Annealing to _ 1300 K yielded a stoichiometric film of SiO,. The subozides are believed to further react with oxygen forming SiO, at an elevated temperature.