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

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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.