Preparation and optical study of APCVD mixed metal oxide films

Mixed metal oxides based on MoO3 and WO3 are prepared by chemical vapor deposition (CVD) using a precursor-mixture of Mo(CO)6 and W(CO)6 powders. By pyrolytical decomposition of the mixed vapors at atmospheric pressure in presence of oxygen, thin films were deposited on silicon substrates at 200°C. The films were characterized by Raman, IR and Ellipsometric Spectroscopies. In as-deposited form the films are amorphous as revealed by Raman spectra. Post-deposition annealing at 200 and 300°C does not significantly change the vibrational and optical properties. Annealing at 400 and 500°C leads to predominantly amorphous structure with appearing of crystalline phase. The character of the absorption spectra and the values of the optical energy bandgap (2.57-2.66 eV) suggest that the CVD-MoO3-WO3 oxide films have highly defective structure