Characterization and Gas Sensing Properties of Spin Coated WO3 Thin Films

Abstract

Abstract The WO3 thin films have been synthesized on to the glass substrates by a simple and easy spin coating method at different deposition cycles and their sensor responses towards various concentrations of NO2 gas were investigated. The WO3 films were spin coated at a spinning rate of 2500–3000 rpm for 5, 10 and 15 deposition cycles, respectively. Then the films were annealed at 400 °C for 1 h in a furnace. The structural, morphological, optical and electrical properties of WO3 films were studied by different characterization techniques such as X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), FT-RAMAN Spectroscopy and electrical resistivity measurements by laboratory made two probe method respectively. It reveals a spherical grain – like morphology with a pure monoclinic phase of WO3. The FT-RAMAN spectra also confirm the pure monoclinic phase of WO3. The WO3-10 film sensor exhibits maximum gas sensitivity 21.93 and 102.4% to 5 and 100 ppm NO2 at 200 °C, respectively. The WO3-10 thin film sensors is highly sensitive and selective to NO2 over other gases.