The interface between silicon and silicon dioxide displays the best electronic characteristics of all known semiconductor/oxide interfaces. Yet the exact interfacial structure remains subject of much controversy. Moreover, little is known about the relevant growth mechanisms. In this study, we combine first principle calculations, infrared spectroscopy and kinetic monte carlo to investigate these basic mechanisms of oxidation. Our Kinetic Monte Carlo approach makes it feasible to deal with the incorporation and agglomeration of oxygen atoms into Si(100). Drawing from infrared measurements and ab initio calculations of static pictures of the surface after oxidant exposure, the Kinetic Monte Carlo technique is optimized to duplicate the experimental conditions (temperature, oxygen coverage...) used in the vibrational experiment. Thus the static picture can be generated from trial elementary mechanisms considered in the Monte Carlo.

We find that the oxide growth is governed by two fundamental phenomena: charge transfer arising from oxygen insertion into Si-Si bond and hydrogen passivation and/or dangling bond formation at the surface. A number of atomistic reactions are identified with their corresponding activation energies. They are discussed as a function of the experimental conditions.