Swift heavy ion provoked structural, optical and electrical properties in SnO2 thin films

SnO2 thin films grown on glass substrates at 300 circle C by reactive thermal evaporation and annealed at 600 circle C were irradiated by 120 MeV Ag9+ ions. Though irradiation is known to induce lattice disorder and suppression of crystallinity, we observe grain growth at a certain fluence of irradiation. X-ray diffraction (XRD) revealed the crystalline nature of the films. The particle size estimated by Scherrer's formula for the irradiated films was in the range 10-25 nm. The crystallite size increases with increase in fluence up to 1 x 1012 ions cm-2, whereas after that the size starts decreasing. Atomic force microscope (AFM) results showed the surface modification of nanostructures for films irradiated with fluences of 1 x 1011 ions cm-2 to 1 x 1013 ions cm-2. The UV-visible spectrum showed the band gap of the irradiated films in the range of 3.56 eV-3.95 eV. The resistivity decreases with fluence up to 5 x 1012 ions cm-2 and starts increasing after that. Rutherford Backscattering (RBS) reveals the composition of the films and sputtering of ions due to irradiation at higher fluence. (orig.)