Effect of high energy Ti9+ ion beam induced modifications in titanium dioxide and tin oxide nanocomposite thin films and detailed analysis of optical, structural and morphological properties

Ion beam irradiation technique plays an important role for modifications in optical, structural, and surface morphological properties of materials. The tin oxide and titanium dioxide nanocomposite thin films were synthesized using RF magnetron deposition technique followed by irradiation with 120 MeV Ti9+ swift heavy ions (SHI). The optical band gap for pristine and irradiated samples was calculated by UV-visible technique and the value of direct band gap decreased from 3.90 eV to 3.75 eV. The refractive index, optical conductivity, Urbach energy, skin depth and optical density have been calculated from the UV-Visible technique. Photoluminescence (PL) technique confirmed the presence of SnO2-TiO2 in the material by showing three standard peaks at 421 nm, 484 sun and 529 nm. Surface morphology of thin film was studied by Atomic Force Microscopy (AFM) technique and it showed grain size dependence on the ions irradiation fluence. The crystallite size was modified by SHI and studied by X-ray diffraction (XRD) technique. The crystallite size increased from 23.97 nm to 26.07 nm as calculated using Debye-Scherrer's formula and it also increased from 54.78 nm to 67.60 nm as obtained by Williamson-Hall equation. Based on the uniform deformation model (UDM), the strain and stress in thin films and dislocation density were calculated. The calculated roughness exponent and RMS roughness varied with irradiation fluence. Depth profiling and elemental analysis were observed by Rutherford Backscattering (RBS) technique.