Synthesis and spectroscopic characterisation of MoO3 thin films

Abstract

MoO₂(acac)₂ has been used as a precursor for the one-step MOCVD of silica- and zirconia-supported MoO₃. Pure films were obtained by suitable control of the deposition parameters. The films were characterised by UV-VIS spectroscopy, XRD, SEM, wavelength-dispersive X-ray fluorescence analysis and XPS. Silica-supported MoO₃ consists of a layered structure packed in the direction of the b axis whilst no preferential orientation was observed for the zirconia-supported films. Films deposited using higher O₂/MoO₂(acac)₂ molar ratios consist of pure MoO₃, whilst lower O₂/MoO₂(acac)₂ values result in the copresence of some Mo suboxides. Deposition rates appear to be largely governed by the O₂/MoO₂(acac)₂ molar ratio and they always increase upon decreasing this parameter. Larger crystallite sizes were found to be associated with slower rate regimes.