XPS AND OPTICAL PROPERTIES OF SOL-GEL PROCESSED VANADIUM PENTOXIDE FILMS

Vanadium pentoxide xerogels were prepared by using sol-gel technology. As-prepared samples of xerogels were heated up to 580 K in order to remove the bonded water. The chemical composition of xerogel samples and thin films has been studied by X-ray photoelectron spectroscopy (XPS). XPS data have shown that pure V2O5 compound was formed. After thermal treatment, in the XPS spectra the main changes occurred in the vicinity of the O is peak due to the removal of water from xerogel. The optical properties of V2O5 films were studied by optical transmission and spectroscopic ellipsometry. Ellipsometric measurements have been carried out in the spectral range of 0.5-5.0 eV at 300 K. The changes in the optical spectra were observed after thermal annealing of as-prepared xerogel samples. The obtained data have shown that thermal treatment of V2O5 thin films has strongly influenced the optical transitions involving both localized and higher-lying conduction bands.