Preparation and photoluminescence of undoped ZnTiO3 thin films

ZnTiO3 thin films were prepared by radio frequency cosputtering of ZnO and TiO2. It was found the as-prepared film is amorphous and the cubic phase ZnTiO3 films form after annealing at temperature above 500 degrees C. The absorption spectra indicate that the optical band gap of the crystalline ZnTiO3 film is about 3.70 eV. A strong photoluminescence band centered at 355 nm consisting of two emission peaks was observed in 800 degrees C annealed ZnTiO3 thin film, and the peak positions of these two emission move to short wavelength with increasing annealing temperature. It was found the emission peak at ultraviolet zone is resulted from O2- vacancy and that in the blue zone is attributed to Zn2+ vacancy.