Structural and optical properties of wet-chemistry Cu co-doped ZnTiO3 thin films deposited by spin coating method

Abstract

Zn1-xTiO3:xCu (x=0%, 1%, 5%) thin films were prepared on glass and quartz substrates via the sol-gel method (wet-chemistry) and spin coating process. Strutural and optical proparties of the prepared films have been characterized by X-ray dif-fraction, field emission scanning electron microscope and UV-visible spectrophotometer. The doping of the thin films by different concentration of Cu ions exhibited change in structure from cubic to hexagonal system.The average crystalline size was calculated from X-ray line broadening and it is decreased from 21.88 nm (ZnTiO3) to 11.21 nm (Zn0.95Cu0.05TiO3). The fundamental optical constants of the thin films (refractive index, absorption coefficient, extinction coefficient, dielectric constant, band gap) were determined using the UV-Vis reflectance and transmittance spectroscopy. The analysis of the optical absorption data revealed that undoped film has indirect transition (Eg = 3.22 eV) and the Cu-doped films have direct allowed transition with band gap energy increased to 3.96 eV.