Oxidation of the 3×3 6H-SiC (0001) adatom cluster: A periodic density functional theory and dynamic rocking beam analysis

Abstract

A dynamic reflection high energy electron diffraction (RHEED) rocking beam analysis has revealed that the twisted adlayer model provided the best fit to an experiment. However, the fitted structural parameters suggest that the surface is only"half-twisted" compared to the full-twisted structure predicted by ab initio calculations. A combined periodic-DFT and dynamical-RHEED calculations show that O2 molecules undergo dissociative adsorption on the topmost adatom cluster site to form the SiO2 species with the chemisorption of one oxygen molecule at the first step, and then form the SiO4 group with the further adsorption of a second oxygen molecule.