Dense electronic excitation induced modification in TiO2 doped SnO2 nanocomposite films
Abstract Nanocomposite thin films of TiO 2 doped SnO 2 were grown on silicon and quartz matrices by electron beam evaporation deposition technique using sintered nanocomposite pellet of SnO 2 /TiO 2 taken in the mass percentage ratio of 90:10. The deposition was done in high vacuum (~10 −6  mbar) condition. 100 MeV Au 8+ Swift Heavy Ion (SHI) beam were used at Inter University Accelerator Center, New Delhi, India for dense electronic excitation in these nanocomposite thin films. The SHI irradiation fluencies were varied from 1 × 10 11  ions/cm 2 to 5 × 10 13  ions/cm 2 . Surface morphology studies and grain growth due to swift heavy ion irradiation induced dense electronic excitation at different ion fluencies characterized by Atomic Force Microscopy–Magnetic Force Microscopy (AFM–MFM) technique using Nanoscope – IIIA shows magnetic nature of grains. Sectional analysis of AFM images shows dependence of grain size on irradiation fluence. Grain size varies between 15 nm and 100 nm at different irradiation ion fluencies. The variation in roughness exponent as calculated from power spectral density data and RMS roughness with respect to irradiation fluence are similar in nature. Amorphous to crystalline phase transformation occurs due to SHI irradiation. The SnO 2 dominated crystalline planes observed at irradiation fluence of 1 × 10 13  ions/cm 2 and 5 × 10 13  ions/cm 2 were (0 2 0), (0 2 1), (1 2 4) and (2 0 4). Literature survey suggests these planes were not achieved by thermal annealing as observed from GAXRD data. At low irradiation fluencies up to 5 × 10 12  ions/cm 2 the variation in optical band gap (∼3.7 eV) was negligible as studied by UV–Visible Spectroscopy. Rutherford Backscattering (RBS) results supports transformation from lower crystalline to higher crystalline state due to absence of any impurities in the samples by 100 MeV Au 8+ SHI irradiation and reduction in RBS yield for Sn and O at highest fluence of 5 × 10 13  ions/cm 2 .