On the optical properties of Ag+15 ion-beam-irradiated TiO2 and SnO2 thin films

The effects of 200-MeV Ag+15 ion irradiation on the optical properties of TiO2 and SnO2 thin films prepared by using the RF magnetron sputtering technique were investigated. These films were characterized by using UV-vis spectroscopy, and with increasing irradiation fluence, the transmittance for the TiO2 films was observed to increase systematically while that for SnO2 was observed to decrease. Absorption spectra of the irradiated samples showed minor changes in the indirect bandgap from 3.44 to 3.59 eV with increasing irradiation fluence for TiO2 while significant changes in the direct bandgap from 3.92 to 3.6 eV were observed for SnO2. The observed modifications in the optical properties of both the TiO2 and the SnO2 systems with irradiation can be attributed to controlled structural disorder/defects in the system.