V2O5 thin films deposited by means of d.c. magnetron sputtering from ceramic V2O3 targets

The deposition of stoichiometric V2O5 films for abrasion-resistant V2O5/TiO2 anatase catalysts was investigated. Direct current magnetron sputtering from ceramic oxide targets in an argon/oxygen atmosphere was chosen as the deposition technique. Layers were prepared with different oxygen mole fractions in the plasma and the influence upon electronic and optical properties was investigated. Surface XPS measurements showed that stoichiometric layers are obtained for low oxygen flows, whereas for higher oxygen contributions reduced vanadium species are increasingly present. This departure from stoichiometry is ascribed to active re-sputtering of the deposited layer by O- ions, due to the higher sputter yield of oxygen compared with vanadium. Polycrystalline V2O5 layers were obtained at elevated substrate temperatures. Optical absorption coefficients in the visible region were found to correlate well with the layer stoichiometry, as deduced from the XPS lineshape analysis. Copyright (C) 2002 John Wiley Sons, Ltd.