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 WO_2.9 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.