Charge-transfer interatomic potential for investigation of the thermal-oxidation growth process of silicon

A charge-transfer interatomic potential, based on the hybrid-Tersoff potential that incorporates a covalent-ionic mixed-bond nature, was developed to reproduce the growth process of the thermal oxidation of silicon. A fitting process was employed with various reference structures sampled by MD. Actively exploring and learning the wide-range of phase space enabled us to develop a robust interatomic potential. Our interatomic potential reproduced the bulk properties of Si and SiO₂ polymorphs well, in addition to the radial distribution function and bond angle distribution of amorphous SiO₂. The covalent-ionic mixed-bond nature of the interatomic potential well reproduced the dissociation process of an oxygen molecule on the Si/SiO₂ interface. The initial oxidation simulation was performed on the silicon surface. We grew the amorphous SiO₂ layer by incorporating the oxygen molecules into the silicon network at the interface. The density of the SiO₂ layer and the charge distribution at the interface showed good agreement with the experimental data.