Effect of surface treatment on SrTiO3 : an x-ray photoelectron spectroscopic study

X-ray photoelectron spectroscopy was used to study the reoxidation kinetics of both mechanically and chemically polished as well as freshly fractured SrTiO3 surfaces. X-ray take-off angles were varied in order to resolve surface contributions from those further into the sample. Most surfaces were found to have Sr/Ti ratios that varied significantly from the stoichiometric ratio of 1. Only the oxygen peaks were found to be take-off angle sensitive. We tentatively identify both adsorbed hydroxyl and carbonate O 1s levels as these angle sensitive peaks, indicating that hydroxyl adsorption occurs very rapidly.