Modification of PLD Grown Nano TiO2 Thin Films using 120 MeV Au Ion Irradiation

Abstract

Nanocrystalline TiO₂ thin films were deposited on quartz and silicon substrates using the PLD method. The pristine film was exposed to 120 MeV Au ions at various fluences from 1×10¹¹ to 1×10¹³ ions/cm². These films were analyzed with XRD, UV-Vis and AFM techniques to examine changes in their structural, optical, and surface properties. The XRD results indicate that the original film is nanocrystalline. The irradiation process causes gradual amorphization. The absorption spectra indicate that lower fluences reduce the bandgap, while the highest fluence increases it. The AFM images of the original film reveal a surface with spherical nanostructures. The lowest fluence increases both grain size and roughness. At intermediate fluences, nanostructures begin to cluster, and at the highest fluence, these spherical nanostructures vanish, resulting in lower surface roughness. The current-voltage (I-V) characteristics show that irradiation consistently decreases electrical conductivity. The changes in structural, optical, surface morphological, and electrical properties due to irradiation are correlated to the high energy deposited through electronic energy loss using thermal spike model.

Keywords: TiO₂ thin films, Swift Heavy Ion Irradiation, XRD, UV-Vis, AFM, I-V Characteristics