Influence of cobalt ion implantation on optical properties of titanium dioxide thin films

Nano-crystalline TiO2 thin films were synthesized by using sol–gel and spin-coating techniques on glass substrates for photo-catalytic applications. Prior to deposition, a TiO2 colloidal suspension was synthesized by microwave-induced thermal hydrolysis of the titanium tetrachloride aqueous solution. In this study, the deposited TiO2 coating with a grain size of 13 ± 2 nm was uniform without aggregation. Co ion implantation into the as-calcined TiO2 thin films was conducted with fluences of 1 × 1015–1 × 1016 doses/cm2 at 40 keV. In addition to the emission of TiO2, the photoluminescence study showed the presence of another Co-related optical center at 405 nm in the Co-implanted TiO2 thin films. Due to the strong capability of forming impurity compounds between the energetic cobalt ions and TiO2, the photoluminescence emission and UV–Vis absorption efficiencies were improved.