Abstract: Perovskite BaTiO₃ thin films were grown on SiO₂/Si (111) substrates by a sol-gel process and rapid thermal annealing (RTA).Surface states and the topmost surface atoms of the BaTiO₃ thin films were analyzed by X-ray photoelectron spectroscopy (XPS) and angle-resolved X-ray photo electron spectroscopy (ARXPS).The results show that the as-fired BaTiO₃ thin films have an enriched-BaO nonstoichiometric surface layer that can be removed by A_r⁺ ion sputtering, and the atomic ratio of Ba to Ti decreases with a decreasing depth from the film surface.

Key words: BaTiO₃ thin film, ARXPS, surface state, XPS, sol-gel process