Effects of depositing temperatures on structure and optical properties of TiO ₂ film deposited by ion beam assisted electron beam evaporation

TiO ₂ , which is high in refractive index and dielectric constant, plays an important role in the fields of optics and electronics. In this work, TiO ₂ films were prepared on glass substrates by the technique of ion beam assisted electron beam evaporation. The films were deposited at 50, 150 and 300 °C, respectively. Then the as-deposited TiO ₂ films were annealed at 450 °C for 1 h in vacuum atmosphere. Structures and optical properties of TiO ₂ films were characterized by XRD, SEM, ellipsometry and spectrophotometer. As a result, the structure and the refractive index of films were improved by both the annealing and the increasing of the deposition temperature. The UV-vis transmittance spectra also confirmed that the deposition temperature has a significant effect on the transparency of the thin films. The highest transparency over the visible wavelength region of spectra was obtained at the deposition temperature of 300 °C. The allowed direct band gap at the deposition temperature ranging from 50 to 300 °C was estimated to be in the range from 3.81 to 3.92 eV.