Influence of Swift Heavy Ion Beam Irradiation on Optical, Structural, and Surface Morphological Properties of WO3 Thin Films Grown by RF Sputtering Method

Abstract

WO₃ is considered to be significant for diverse applications such as gas sensing, photocatalysis, and photovoltaic devices because of its wide optical band gap. Ion beam treatment of various metal oxides produces defects that modify various properties including the morphological, structural, and optical properties of the metal oxides. When the energetic ions cross through the target materials, two kinds of energy losses occur, i.e., nuclear and electronic energy loss. In high-energy ion beam treatment of thin films, electronic energy loss is dominant over nuclear energy loss. In our current study, thin films of tungsten oxide were grown on a substrate of glass and silicon by the radio frequency (RF) sputtering method. The sputtered WO₃ thin films were exposed to an ion beam of Ag ion with an energy of 120 MeV at various fluence levels of 1.0 × 10¹² ions/cm², 5 × 10¹² ions/cm², and 1.0 × 10¹³ ions/cm². Optical study revealed changes in the energy band gap of ion-irradiated WO₃ thin films. From Raman spectroscopy, the phase observed was monoclinic for pristine and irradiated samples. PL spectroscopy of the pristine and ion beam-implanted WO₃ thin films showed emission spectra at a wavelength 437 nm with an excitation wavelength of 420 nm. X-ray photoelectron spectroscopy showed the presence of W and O atoms and showed changes in the electronic structure after Ag ion beam irradiation.