Structural and gasochromic properties of epitaxial WO films prepared by pulsed laser deposition

Yamamoto, Shunya; Inoue, Aichi; Yoshikawa, Masahito

We investigated the structural and gasochromic properties of epitaxial tungsten trioxide (WO) thin films on the -AlO r-plane substrates, prepared by ArF excimer pulsed laser deposition under the controlled oxygen atmosphere. The deposited films were characterized by Rutherford backscattering spectroscopy (RBS)/channeling, X-ray diffraction and Raman spectroscopy. RBS and XRD results demonstrated that monoclinic WO(001) films were successfully grown on the -AlO substrates. The crystal quality was improved by increasing both the oxygen pressure and the substrate temperature. Gasochromic coloration in the WO films by exposure to diluted hydrogen gas was found to correlate with the crystal quality of the films. The gasochromic coloration was suppressed by the epitaxial growth of the films.