250Â keV Ar2+ ion beam induced grain growth in tin oxide thin films

Nanocrystalline tin oxide (SnO2) thin films of 200 nm thickness were deposited on quartz and sapphire substrates by e-beam evaporation method. The substrate temperature was kept at 200 °C to enhance the surface diffusion of the atoms. The films were characterized by atomic force microscopy (AFM), glancing angle X-ray diffraction (GAXRD) and UV-visible spectroscopy for morphological, structural and optical characterization respectively. The nanocrystalline grains are found to be 4 ± 2 nm in radius. These nanocrystalline thin films were bombarded by 250 keV Ar+ beam to study ion beam induced grain growth and surface modification. There occurs red shift in UV/visible absorption band edge of tin oxide thin films after ion bombardment, confirming quantum confinement effect. GAXRD and AFM studies show agglomeration of nanocrystalline grains after Argon ion bombardment in the keV energy range. Ion beam induced defects enhance the diffusion of atoms leading to uniformity in size.