SiO desorption kinetics of Si(111) surface oxidation studied by real-time photoelectron spectroscopy

The kinetics of the initial oxide growth on the Si(111) surface have been investigated using real-time photoelectron spectroscopy and density functional theory (DFT) calculations. Including SiO desorption into the description of the transition from Langmuir-type adsorption to two-dimensional (2D) oxide island growth reveals that oxidation at high temperature T and low oxygen pressure PO2 is not governed by 2D oxide island growth despite sigmoidal oxygen uptake curves. Because SiO desorption during the initial oxide growth depends strongly on temperature and oxide coverage oxide in the transition region, an initial oxidation model for the transition region is proposed. According to PO2-dependent experimental results and theoretical calculations, the frequent occurrence of SiO desorption is due to the formation of the transition state tri-ins×2 species, SiO desorption during the initial oxidation is suppressed by the most thermally stable oxygen adsorption species tri-ins×3 formed on Si(111)7×7.