Evolution of damage fraction due to dense ionizing irradiation on TiO2 film

The evolution of damage fraction during dense ionizing irradiation at various fluences using 100 MeV Ag ion is studied. Irradiation induced modification of surface roughness and surface potential of titanium dioxide nanocrystalline thin films are estimated. TiO2 thin films deposited on Si (1 0 0) substrate were irradiated by 100 MeV Ag ion beam with varying fluences. Ion bombardment generates point and extended defects in TiO2 thin films due to dense electronic excitation. The surface morphology and surface roughness of irradiated and pristine thin films were measured using atomic force microscopy. The changes in surface potential of pristine as well as Ag ion beam irradiated thin films were measured from contact potential difference between TiO2 thin film (one electrode) of unknown work function and Au (reference electrode) of known work function using scanning Kelvin probe microscopy. The defect size and damage fraction are calculated from exponential fitting of variation of both contact surface potential difference and roughness exponent with fluence.