On the structure, stress and optical properties of CVD tungsten oxide films

Tungsten oxide thin films were prepared by low temperature chemical vapor deposition (CVD) process from a metallorganic precursor at atmospheric pressure. The influence of the deposition temperature and oxygen flow-rate on the film structure, density and built-in stress were investigated in a comparative way employing different characterization techniques. The XRD structural analysis of the films showed co-existence of WO3 and WO2.9 phases. On the basis of the performed studies it was inferred that the film density decreases, the film stresses change and the film transmission increases at higher oxygen flow-rate values during the deposition. The growth window for preparation of tungsten oxide films with very low density, facilitating fast kinetics of the electrochromic effect, was established.