The structure of the SiO2∕Si(100) interface from a restraint-free search using computer simulations

Abstract

The structure of the interface between SiO2 and Si(100) is investigated using the replica-exchange method driven by classical molecular dynamics simulations based on ab initio-derived interatomic potentials. Abrupt interfaces are shown to be unstable, whereas a substoichiometric oxide forms at the transition between the two materials that exhibits Si atoms in all three intermediate oxidation states, in agreement with experiment. A number of physical characteristics are found to be consistent with experimental data, including the distribution of Si atoms with different oxidation states, the increase in atom density and the stability of a pseudo-cristobalite pattern at the interface as well as the presence of Si–O–Si bridge bonds between the substrate and the suboxide.