Structural and gasochromic properties of WO₃films prepared by reactive sputtering deposition

The effects of deposition temperature and film thickness on the structural and gasochromic properties of tungsten trioxide (WO 3 ) films used for the optical detection of diluted cyclohexane gas have been investigated. The WO 3 films were prepared on SiO 2 substrates by magnetron sputtering, with the deposition temperature ranging from 300 to 550 °C in an Ar and O 2 gas mixture. The films were characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Rutherford backscattering spectroscopy (RBS). The gasochromic properties of the WO 3 films, coated with a catalytic Pt layer, were examined by exposing them to up to 5% cyclohexane in N 2 gas. It was found that (001)-oriented monoclinic WO 3 films, with a columnar structure, grew at deposition temperatures between 400 and 450 °C. Furthermore, (010)-oriented WO 3 films were preferably formed at deposition temperatures higher than 500 °C. The gasochromic characterization of the Pt/WO 3 films revealed that (001)-oriented WO 3 films, with cauliflower-like surface morphology, were appropriate for the optical detection of cyclohexane gas.