TiO<sub>2</sub> thin films were deposited on the glass substrates by dc reactive magnetron sputtering technique at different sputtering pressures. The films prepared at low pressures have an anatase phase, and the films prepared at high pressures have an amorphous phase. The optical properties were studied by measuring the transmittance and the ellipsometric spectra. The optical constants of the films in the visible range were obtained by fitting the transmittance combined with the ellipsometry measurements using the classical model with one oscillator. The films prepared at the pressure higher than 6 x 10<sup>-3</sup> mbar show a volume inhomogeneity. This volume inhomogeneity has been calculated by fitting the transmittance and the ellipsometric spectra.
The refractive index (n), the extinction coefficient (κ), dielectric constant ε, free carrier density (n<sub>c</sub>) and the carrier mobility (μ) of the ITO (Indium-Tin-Oxide) films with different deposition time (or thickness), oxygen partial pressure ratio (P<sub>O2</sub>) and annealing temperature were measured and studied. The calculated optical parameter-extinction coefficient (κ) was obtained from the diffuse reflectance spectra using "scattering model". The Lorentz oscillator classical model has also been used for fitting the ellipsometric spectra in order to obtain both n and κ values. As comparing the Swanepoel method was used for the refractive index. Clearly the results of the "scattering model", Swanepoel method and Ellipsometric method agree in magnitude. The films prepared at different P<sub>O2</sub> show different behaviour of the refractive index and extinction coefficient. The electrical characteristic parameter n<sub>c</sub> and μ were compared and studied by experimental measurements and calculations using an equation that relates the dielectric function and photo-energy (Drude theory) by Mathematic-4.1 software. Both measured and calculated values coincide in magnitude.