Transparent rutile TiO2 films prepared by thermal oxidation of sputtered Ti on FTO glass

Abstract

TiO₂ films were prepared via a two-step fabrication process, i.e. deposition of Ti films by magnetron sputtering on an FTO glass substrate followed by thermal oxidation at 600–725 °C. The investigated parameters were Ti layer thickness, temperature of oxidation and deposition conditions (pre-treatment and substrate heating). Such TiO₂ films have a rutile structure and contain metallic Sn which is the result of a thermal reaction at the interface between SnO₂ and Ti at temperatures above 500 °C. A calcination temperature of 600 °C is optimal for fabricating TiO₂ films with significant photoelectrochemical response. Heating of the FTO substrate during magnetron sputtering deposition of Ti films results in a significant improvement of the compactness of the TiO₂ films. A similar but not so pronounced improvement was observed for the TiO₂ films deposited on the FTO substrate pre-treated with radio-frequency plasma under Ar–O₂ and N₂–H₂ atmosphere. The observed correlation between the increased content of Sn in the TiO₂ films and compactness of the TiO₂ films supports the explanation of both positive effects by better adhesion of the Ti films to the FTO substrate.