Impact of first-step potential and time on the vertical growth of ZnO nanorods on ITO substrate by two-step electrochemical deposition

•We grew vertical ZnO nanorods on ITO substrate using a two-step continuous potential process.•The nucleation for the ZnO nanorods growth was changed by first-step potential and duration.•The vertical ZnO nanorods were well grown when first-step potential was −1.2V and 10s. In this study, we analyzed the growth of ZnO nanorods on an ITO (indium doped tin oxide) substrate by electrochemical deposition using a two-step, continuous potential process. We examined the effect of changing the first-step potential as well as the first-step duration on the morphological, structural and optical properties of ZnO nanorods, measured via using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and photoluminescence (PL), respectively. As a result, vertical ZnO nanorods were grown on ITO substrate without the need for a template when the first-step potential was set to −1.2V for a duration of 10s, and the second-step potential was set to −0.7V for a duration of 1190s. The ZnO nanorods on this sample showed the highest XRD (002)/(100) peak intensity ratio and the highest PL near band edge emission to deep level emission peak intensity ratio (NBE/DLE). In this study, the nucleation for vertical ZnO nanorod growth on an ITO substrate was found to be affected by changes in the first-step potential and first-step duration.