Electrochemical deposition and characterization of wide band semiconductor ZnO thin film

ZnO thin film was electrodeposited from an aqueous solution of Zn(NO3)2 at 65 °C on indium tin oxide (ITO)-covered glass substrates. Atomic force microscope and X-ray diffraction studies indicated that the obtained ZnO films were polycrystalline with hexagonal wurtzite-type structure. Various operating conditions were controlled, including the applied voltages, the deposition time and annealing treatment. According to applied conditions, ZnO films presented different morphologies, grain size ranging approximately from 180 to 320 nm. When depositions were carried out at −0.9 and −1.0 V, ZnO films were compact and homogeneous, and their transmittance was close to 95% at the wavelength of 500 nm. The variations in the band gap of ZnO films deposited under different conditions are also discussed.