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

The influence of O-2 upon electrical properties has been examined on anatase titania (TiO2) thin films prepared by a sol-gel dip-coating method. When O-2 is turned on, a rapid and considerable decrease in electrical conductivity is detected at 500 degrees 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.