Influence of gamma radiation on optical, structural and surface morphological properties of WO3 thin films grown by RF sputtering

In the present study, tungsten oxide (WO3) thin films were grown on glass and silicon substrates using RF sputtering method and thin films were annealed at 550 degrees C. The prepared WO3 thin films were exposed through gamma irradiation by varying doses at 100, 200, 300, 400 and 500 kGy. The modification in optical, structural, morphological and chemical properties of WO3 thin films before and after gamma irradiation doses were observed from UV-Vis, Photoluminescence (PL) and Raman spectroscopy, Fourier Transform spectroscopy (FTIR), Atomic Force Microscopy (AFM), X-ray diffraction (XRD), Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS). The grain size after gamma irradiation reduced from 6.56 nm to 3.40 nm. The Raman spectroscopy reveals the monoclinic phase of tungsten oxide thin films after gamma irradiation. XRD pattern shows the variation in crystallite size from 7.2 nm to 33.8 nm. The optical band gap of pristine and gamma irradiated thin films was observed from UV-Vis spectroscopy. The functional groups were confirmed by FTIR spectroscopy. PL emission peaks were observed at 415 nm and 475 nm for pristine and gamma irradiated thin films at excitation wavelength of 380 nm. The XPS study reveals the presence of W and O atoms in pristine and gamma irradiated WO3 thin films.