Optical and electrical properties of TiO2 based transparent conductive films and multilayer systems fabricated by radio frequency sputtering and e-beam evaporation

Conductive non stoichiometric TiO2-based films attract considerable interest for their photocatalytic, photovoltaic and photoelectrochemical applications. In this work, transparent and conductive TiOx and TiO2:Nb films were fabricated by e-beam evaporation at 250°C in oxygen deficient atmosphere starting from commercial powders, while TiO2:Nb films and TiO2:Nb/Ti multilayer systems were grown at room temperature by radio frequency sputtering in Ar atmosphere starting from TiO2:Nb and Ti targets. In all cases, an accurate control of oxygen partial pressure during the growth process was necessary and, in some cases, additional post deposition treatments in reducing atmosphere were applied aiming to decrease the electrical resistivity of the samples. The optical, electrical, structural and morphological characteristics of the different films were investigated and correlated to the process parameters.