Gas sensitive behaviour and morphology of reactive evaporated V2O5 thin films

The gas-sensing characteristics and the morphology of vanadium pentoxide thin films have been investigated. The thin films were prepared by reactive electron beam evaporation of vanadium on surface-oxidised silicon wafers and additional thermal oxidation. Structural and morphological analyses of the V2O5 thin films in the thickness range of 100-200nm were performed. The polycrystalline monophase V2O5 films consist of grains with surface areas in the range of 100 nm to 1 mum square. Gas measurements were carried out with single-chip thin-film sensor arrays in synthetic air with 50% humidity. The sensors are analytically suitable as they are sensitive to ammonia, methane, carbon monoxide and nitric dioxide. Particularly for NO2, a distinctive temperature dependence of the gas reaction has been observed.