Effect of ZnCl2 concentration on the growth of ZnO by electrochemical deposition

ZnO thin films were prepared by an electrochemical deposition route on Zn/Si substrates. The effect of zinc chloride concentration on the optical and structural properties of ZnO was investigated. With the increase of concentration of ZnCl2, the morphologies of ZnO thin films were varied from thin films to sheet-like shapes. For low concentrations less than 10 mM, the dense ZnO thin films with the nano-sized grains were formed. For high concentrations above 50 mM, the films was composed of large plates of Zn5(OH)8Cl2 and their morphologies were strongly affected by thermal annealing. According to X-ray diffraction (XRD) and photoluminescence (PL) results, the crystallinity of ZnO thin film was significantly improved through annealing at 300 °C.