The role of passivation in titanium oxidation: thin film and temperature effects

Through the combined application of Auger electron spectroscopy (AES) and factor analysis (FA), we have studied the oxidation process of titanium under different regimes: bulk and thin film at room temperature (RT) and high temperature (HT). While the saturation regime at RT is produced by the formation of a passivated TiO2 film at the surface of bulk and thick oxide films, the saturation is governed by the substrate/titanium film interactions in the case of thinner films. The stoichiometry of the obtained oxide films also depends on the oxidation process. We found only TiO2 for RT bulk oxidation, Ti2O3 and TiO2 for HT, and TiO and TiO2 for thin films. Heating the sample, once the RT saturation was achieved, produces additional oxidation (post-oxidation), but the stoichiometry of the oxide films remains unchanged. For the thinner films, the post-oxidation produces almost no effect.