ArF Eximer Laser Deposited Tin Oxide Films Studied by "in situ" Surface Diagnostics and by Synchrotron Radiation Induced UV Photoemission

Tin oxide films were deposited by ArF excimer laser induced photolysis of Sn(CH3)4/O2 mixtures. The "in situ" Auger analysis was used to determine the effect of the gas-phase oxygen concentration on the film composition. The surface properties of the films were investigated by synchrotron radiation UV photoemission spectroscopy. To this aim samples were transferred to a synchrotron radiation facility, without any exposure to air and kept in dynamical high vacuum. The results obtained showed that the valence-band spectrum was characteristic for SnO2 and that the Sn 4d core peak did not have any contribution due to metallic tin. Furthermore, by tuning the synchrotron radiation photon energy, in order to vary the photoelectron escape depth, we got the indication that the oxygen vacancies responsible for the weak emission in the band-gap region were localized at the sample surface.