Low energy Kr5+ ion beam engineering in the optical, structural, surface morphological and electrical properties of RF sputtered TiO2 thin films

Abstract

Titanium dioxide (TiO2) thin films were grown on Silicon and glass substrates at room temperature by RF sputtering deposition technique. All deposited thin films were irradiated by 800 keV Kr5+ low energy ion beam with varying ion fluence from 1E15 ions/cm2 to 1E17 ions/cm2. The decreases in crystallite size from 42.09 nm to 27.36 nm (by Scherrer's formula) with increased in ion fluence were observedusing X-ray Diffraction (XRD) technique. The orientation of the different planes was observed but the plane (112) confirmed the preferred orientation as determined by the texture coefficient using XRD patterns. The surface morphology of the samples was studied by Atomic Force Microscopy (AFM) technique in the tapping mode and the Root Mean Square (RMS) roughness (Rq) was found to be increased from 0.739 nm to 3.20 nm with increases the ion fluence. The energy bandgap was found to be increased from 4.06 eV to 4.30 eV by increased in ion fluence due to electron confinement at nano-scale and also observed Urbach energy and optical conductivity by UV–Visible spectroscopy. The Urbach energy of thin films was observed to increased with increasing the ion fluence. The photoluminescence (PL) spectra confirmed the enhancement in the recombination of electron hole pair with increases the oxygen vacancies by increases the ion fluence. The peak at 382 nm was observed at higher fluence of 7E15 ions/cm2, 3E16 ions/cm2 and 1E17 ions/cm2. In the Raman studies, all six Raman modes at their positions for anatase phase of TiO2 thin films were successfully observed. The thickness of thin films was observed 268 nm and elemental composition of titanium and oxygen in all thin films were confirmed in the ratio of 1:2 by using Rutherford Backscattering Spectrometry (RBS). The electrical properties were studied by measuring the variation of current (I) with respect to the applied potential (V) at room temperature and the conductivity of the irradiated thin films was decreased with increases of ion fluence.