Mixed metal oxides based on MoO_3 and WO_3 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-MoO_3-WO_3 oxide films have highly defective structure.
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