Optical constants of thin CVD-Tungsten oxide films

CVD-tungsten oxides were obtained at 300 degree(s)C on glass substrates by pyrolitical decomposition of W(CO)6 vapor in argon/oxygen stream at atmospheric pressure. The thin films were examined by spectroscopic ellipsometry in the wavelength range of 0.3 - 0.8 micrometers . It was found that as- deposited oxides are rather porous and predominantly amorphous but crystalline phase is also present. During the annealing at 450 and 500 degree(s)C the oxide becomes fully crystallized and yet it preserves its porosity. The high level of porosity is reflected in the low values of the refractive indices (1.9 - 1.5) and the optical band gap energies (3.04 - 3.11 eV).