Optical properties of SrTiO_3 thin films deposited by radio-frequency magnetron sputtering at various substrate temperatures

摘要

SrTiO_3 thin films were deposited on vitreous silica substrates at various substrate temperatures (300-700℃) by rf magnetron sputtering technique. The transition from amorphous phase to polycrystalline phase for the films occurred at the substrate temperatures of 300-400℃. Their optical properties were investigated by transmittance measurements. The fitting method was used to calculate the refractive index and the film thickness from the transparent region of the transmittance spectra. The refractive index increased and the film thickness decreased with the substrate temperatures increasing. The dispersion of the refractive index was studied by considering a single electronic oscillator model. The band gaps of the films were estimated from Tauc's law and showed a decreasing tendency to that of the bulk SrTiO_3 with the substrate temperatures increasing. These results provide some useful references for the potential application of SrTiO_3 films in integrated optics devices.