200 MeV Ag15+ ion beam irradiation induced modifications in spray deposited MoO3 thin films by fluence variation

Spray deposited Molybdenum trioxide (MoO3) thin film of thickness nearly 379 nm were irradiated with 200 MeV Ag15+ ion beam at different fluences (Ø) of 5 × 1011, 1 × 1012, 5 × 1012 and 1 × 1013 ions/cm2. The X-ray diffraction (XRD) pattern of the pristine film confirms orthorhombic structure and the crystallinity decreased after irradiation with the fluence of 5 × 1011 ions/cm2 due to irradiation induced defects and became amorphous at higher fluence. In pristine film, Raman modes at 665, 820, 996 cm−1 belong to Mo–O stretching, 286 cm−1 belong to Mo–O bending mode and those below 200 cm−1 are associated with lattice modes. Raman peak intensities decreased upon irradiation and vanished completely for the ion fluence of 5 × 1012 ions/cm2. The percentage of optical transmittance of pristine film was nearly 40%, while for irradiated films it decreased significantly. Red shift was observed for both the direct and indirect band gaps. The pristine film surface had densely packed rod like structures with relatively less porosity. Surface roughness decreased significantly after irradiation. The electrical transport properties were also studied for both the pristine and irradiated films by Hall effect. The results are discussed. Keywords: Ion beam technology, MoO3 thin films, Spray coatings, Optical materials and properties, Radiation damage