XPS study of Nb-doped oxygen sensing TiO2 thin films prepared by sol-gel method

Titanium dioxide (TiO2) thin films have been prepared using the sol-gel method and subsequently doped with niobium oxide (Nb2O5) for use in oxygen sensing applications. The chemical composition of the resultant film sensor surface has been investigated using X-ray pholoelectron spectroscopy (XPS). Films are essentially stoichiometric with carbon as the dominant impurity at the surface. The film electrical resistance has been examined for detection of oxygen at concentrations of 1 ppm to 1%. Doping resulted in a 40% increase in the oxygen gas sensitivity of the thin films at an operating temperature, as low as 190 degrees C. (C) 1998 Elsevier Science S.A. All rights reserved.