Investigation of the structure of tungsten oxide films obtained by chemical vapor deposition

Abstract

Thin amorphous and polycrystalline tungsten oxide films have been prepared by Chemical Vapor Deposition (CVD) from metallorganic precursor − tungsten hexacarbonyl − at atmospheric pressure. The dependence of the composition and the structure of tungsten oxide films on the technological conditions has been investigated by XPS, XRD, DTA-TGA and Raman spectroscopy. As a result it has been established that: at high values of the flow-rates of the reaction gases amorphous films of very low density have been obtained; in the XPS spectra of the understoichiometric WO3−y (0 < y < 0.3) films besides W6+, also W5+ and W4+ states have been observed. First to observe in the Raman spectra of amorphous CVD-WO3 films is the band at ~ 950 cm−1, characteristic for terminal W6+ = O bonds in result of the presence of structural water. The existence of structural water in the amorphous material has been established by thermal analyze, also.