Oxidation process in titanium thin films

Abstract

The first stages of the oxidation process of titanium thin films deposited on top of Cu(100) substrates have been studied by means of Auger electron spectroscopy. Using principal component analysis we found different oxidation regimes for Ti films depending on their thickness. While for a film thickness up to 1 ML only one oxide phase (${\mathrm{TiO}}_{2}$) is present, in thicker films a new oxide phase (${\mathrm{TiO}}_{\mathrm{x}}$; x2) is detected. As the Ti film grows, the passivating effect of the titanium oxide stops the process of oxygen adsorption. Finally, for the thickest films (>7 ML) the effect of the interface turns out to be negligible and the oxidation characteristics of bulk titanium are recovered; i.e., only ${\mathrm{TiO}}_{2}$ is detected again.