Studies of dense electronic excitation-induced modification in crystalline Fe-doped SnO2 thin films

Dense electronic excitation-induced modification in thin films of Fe-doped tin oxide (SnO2) grown by RF sputtering technique was done by irradiating swift heavy ion (SHI) beams of 100 MeV Au8+ with varying ion fluencies from 5 × 1011 to 1 × 1013 ions/cm2. While the AFM results exhibit grain size dependence on irradiation fluence, MFM images show uniformly distributed magnetized nanoparticles over the entire surface after irradiation. GAXRD pattern indicates particle size variation (from 5 to 26 nm) due to irradiation and higher stability of (1 0 1) other planes against irradiation. Our reported results show that the surface energies of ESurf(1 0 1) > ESurf(1 1 0) in rutile structure of SnO2. Change in optical band gap between 3.78 and 5.08 eV due to variation fluence was observed. This is attributed to variation in particle size, scattering due to surface roughness and modification in local electronic structure. RT magnetic studies done by SQUID shows that coercivity increases up to the fluence of 5 × 1012 ions/cm2 (157.71 Oe). The increase in coercivity is due to oxygen vacancies created and change in local electronic structure of Sn due to recoil implantation. Resonance RBS results confirm the presence of Fe in the samples with a new observation where increase in peak intensity of Sn after irradiation occurred. The presence of X-ray absorption near-edge structure spectra at O K-edge around 532.63 eV in pristine and irradiated samples confirms the doping of Fe at the lattice site of Sn in SnO2. Evolution of new spectral features at 486.09, 486.75, 491.40, 492.85 and 499.14 eV for XANES at Sn M-edge was obtained after irradiation.