Abstract
Optical Characterizations of annealed TiO2 thin films have been discussed. Samples have prepared by sputtering technique at different reactive oxygen gas rates, R (1.00%≤R≤30.00%). The pressure within the sputtering room was fixed at 7.5 × 10−7 Pa by controlling the rate of introducing pure Ar and O2 gases. All film-samples were annealed in vacuum at 500 °C for 2 h. X-ray diffractograms revealed that annealed samples have polycrystalline nature of tetragonal anatase phase. Optical transmission and reflection were employed to study optical properties. Optical energy-gap values decrease from 3.38 eV to 2.91 eV for direct transition and from 3.12 eV to 2.10 eV for indirect transition, respectively. While, Urbach's energy values increase from 686 meV to 884 meV as R-value increased. Wemplee Di-Domenico model and Sellemeier postulate were utilized to study the refractive index dispersion and oscillator parameters. All estimated optical parameters are strongly dependent upon the flow rate of oxygen.
•Sputtered thin-film TiO2 samples of different rates of oxygen flow (1%≤R≤30%) were prepared.•Dependence of optical properties on the oxygen flow rate and photon energy were studied.•The optical energy gap arose from direct and indirect electronic transition.•The refractive index dispersion and dispersion energy parameters were studied and discussed.•Novel optical data have been studied and discussed.