Meso-porous-like tungsten oxide structure: a study on some physical properties at different deposited temperatures

Abstract

Polycrystalline tungsten oxide (WO3) thin films were prepared using the spray pyrolysis method at various substrate temperatures (200, 250, 300, 350, and 400 °C) on the quartz substrate. The X-ray diffraction pattern showed polycrystalline films with a monoclinic structure. Analysis using field-emission scanning electron microscopy revealed a porous fibrous reticulate morphology. The EDs results reflected the formation of stoichiometric films with optimum stoichiometry at 350 °C substrate temperature. The transmittance spectra at the 300–1100 nm spectral range reached about 55% with a direct band gap of 3.3 eV. The optical constant was also estimated and analyzed, where optical conductivity was found to be about 5.4669 x1014 (Ω cm)-1 while, 2.09 eV was the value of Urbach energy at 350 °C.