Vertical growth of ZnO nanorods on ITO substrate by using a two-step-potential electrochemical deposition method

Abstract

In this study, we grew vertical ZnO nanorods on indium-doped tin-oxide (ITO) substrate by using an electrochemical deposition. For the growth, we used a two-step, continuous potential process without a template, additives, catalysts or a seed buffer layer. The morphological, structural and optical properties of ZnO were investigated using field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoluminescence (PL), respectively. The best test conditions resulted in the growth of vertical ZnO nanorods with a height of 550 nm and occurred when a first-step potential of −1.2 V was applied for 10 s, and a second-step potential of −0.7 V was applied for 1190 s. ZnO nanorods grown at the optimized growth condition show the strongest (002) peak intensity in the XRD spectrum and the highest near band edge emission over deep level edge emission (NBE/DLE) peak ratio of 76.26 and the lowest full width at half maximum (FWHM) of 144 meV in the photoluminescence spectrum. In our study, the structural and the optical properties of ZnO nanorods were highly improved, as compared with a constant single potential for 1200 s, when a first-step potential of −1.2 V was applied for 10 s and was followed by a second-step potential of −0.7 V which was applied for 1190 s.