Effect of oxygen partial pressure on the structural and optical properties of ion beam sputtered TiO2 thin films

Thin films of TiO2 were grown on quartz substrate at various oxygen partial pressure using ion beam sputtering technique. The surface, structural and optical (linear and nonlinear) properties of the deposited films were studied using X-ray reflectivity, atomic force microscopy and diffraction technique, UV-vis spectroscopy and Z-scan technique, respectively. A transition from amorphous to crystalline nature of the films, decrease in energy band gap and increase in nonlinear absorption coefficient were observed with increase in oxygen partial pressure. The improved nonlinear absorption coefficients and the saturable absorber response of the films suggest the utility of the grown TiO2 thin films as saturable absorbers.