Micro electronic and macro optical parameters of the ITO films prepared by DC sputtering for electrochromic applications

The refractive index (n), the extinction coefficient (kappa), dielectric constant epsilon, free carrier density (n(c)) and the carrier mobility (mu) of the ITO (Indium-Tin-Oxide) films with different deposition time (or thickness), oxygen partial pressure ratio (P-O2) and annealing temperature were measured and studied. The calculated optical parameter-extinction coefficient (kappa) 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 K 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-O2 show different behaviour of the refractive index and extinction coefficient. The electrical characteristic parameter n(c) and mu 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.