Structure and optical anisotropy of pulsed-laser deposited TiO2 films for optical applications

The evolution of the crystal, the microstructural and the optical properties of pulsed-laser deposited TiO₂ films, investigated by X-ray diffraction, atomic force microscopy, scanning electron microscopy, optical transmittance and m-line spectroscopy measurements are reported. The samples were grown on (0 0 1) SiO₂ substrates at temperatures from 250 to 600 °C and oxygen pressures from 1 to 15 Pa. Crystalline films consisting of single anatase or anatase and rutile phases, were obtained at temperatures higher than 400 °C. A tendency toward columnar-like growth morphology was observed in the samples. Strong dependence of the optical properties on the surface roughness and the microstructure was determined. All films revealed single-mode waveguiding and optically anisotropic properties.