SHI induced modifications in SnO2 thin films: Structural, optical and surface morphological studies

Tin oxide (SnO2) thin films were deposited on quartz and Si substrates by thermal evaporation method. These films were irradiated by 100 MeV Ag ions at different fluences ranging from 1 × 1012 to 1 × 1013 ions/cm2. Pristine and irradiated films were characterized using X-ray diffraction (XRD) for structural analysis, UV–Vis spectroscopy for optical properties and atomic force microscopy (AFM) for morphological changes to study the modifications induced by irradiation. As deposited films showed the amorphous nature on both the substrates, which crystallized after irradiation as inferred from XRD spectra. It is also observed that the crystallization is better in the films grown on Si substrate rather than the films on quartz substrate. UV–Vis study showed red shift at the lower fluences up to 3 × 1012 and blue shift at the fluence of 1 × 1013 ions/cm2. The pristine films on both the substrates are featureless as observed in AFM micrograph. Surface structures are randomly distributed and have broader size distribution. Roughness of the films were increased at initial fluences up to 3 × 1012 ions/cm2 and then decreased with further increase in fluence. Moreover, irradiation has induced the formation of regular shape structures with narrow size distribution. The results may be attributed to the energy deposited by swift heavy ion (SHI) in the film.

► Thermally evaporated tin oxide (SnO2) thin films were irradiated by SHI.
► Irradiation induces nanocrystallization in initially amorphous SnO2 thin films.
► Optical absorption of the films can also be modified using SHI irradiation.
► Surface nanostructures are formed due to irradiation induced surface diffusion.
► Shape and size of the nanostructures can be varied with ion fluence.