ESCA INVESTIGATION OF SNOX FILMS USED AS GAS SENSORS

The electronic properties of amorphous and ion-implanted polycrystalli ne SnO2 films have been studied using x-ray photoemission spectromicro scopy. First, we analysed the degree of oxidation and the homogeneity of as-deposited films. The SnO and SnO2 phases were identified from th eir valence band spectra rather than from the Sn 3d core level spectra . Then we studied the damage effects due to the implantation of Pd+ an d Ga+ ions in polycrystalline films. The ion bombardment of SnO2 films results in drastic changes of valence-band spectra which is correlate d to compositional changes. Annealing in air at 600-degrees-C for 4 le ads to complete recovery of radiation damage. However, after such ther mal annealings, the film surface still contains a relatively high amou nt of SnO (5-10%).