Oxygen detection in sol–gel derived titania thin films doped with tantalum

Abstract

The influence of O₂ upon electrical properties has been examined on anatase titania (TiO₂) thin films prepared by a sol–gel dip-coating method. When O₂ is turned on, a rapid and considerable decrease in electrical conductivity is detected at 500°C in the TiO₂ film doped with Ta, although the conductivity remains almost constant in a pure TiO₂ film. A complex impedance analysis reveals that the variation of conductivity is mainly dominated by the grain-boundary resistance. Surface segregation of Ta ion is suggested at higher Ta concentration by X-ray diffraction analysis.