Structural and Optical Characteristic of Cu-Doped TiO<inf>2</inf> Thin Film

Abstract

Ti1−xCuxO2 (x = 0, 0.05, 0.1, 0.15, 0.2) thin films were formed using spray pyrolysis technique. Rietveld analysis was applied to trace the phases formed in each film. The lattice parameter and crystallite size were affected by the amount of Cu doping and the present of CuO phase at the higher doing amount. The interatomic distances of the Ti polyhedral are changed upon on doping. The effect of Cu doping rations on absorbance, transmittance, extinction coefficient, refractive index, opto-electric properties and non-linear optical parameters of TiO2 films was investigated using UV–visible spectroscopy technique. The optical bandgap energy (Eg) value of TiO2 film is 3.55 eV and it reduced to 3.24 eV as the amount of Cu doping became 10%. After that two band gaps were appeared at (3.1, 3.35) and (3.15, 3.38) eV for 15 and 20% Cu doping, respectively. All films displayed the normal dispersion characteristics. The nonlinear optical parameters and electric properties for all doped films are higher than the undoped one. Density functional calculation (DFT) was used to explain the reason for reduction of the optical band gap upon doping TiO2 with Cu.