Effects of Solution Precursor on Structural, Morphological, and Photoelectrochemical Properties of ZnO Layers Deposited by Recurrent Cyclic Voltammetry

Abstract

The effects of the choice of the starting solution on the crystalline growth and structural and photoelectrochemical properties of zinc oxide films deposited on conductive (fluorine-doped tin oxide) glass substrate by cyclic voltammetry at 70°C have been studied. The morphology of the deposits was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The photoelectrochemical response in K2SO4 solution was followed by voltammetry and chronoamperometry. X-ray diffraction analysis revealed hexagonal wurtzite crystalline structure for all the films, with randomly oriented crystallites for the ZnO film prepared from zinc chloride or from an equimolar mixture of zinc chloride and zinc nitrate. Meanwhile, the films developed from zinc nitrate or from zinc acetate solution presented preferential (002) orientation. SEM revealed nanometric grains with hexagonal shape for all the films. The effects of the choice of the precursor on the symmetry, kurtosis, and roughness of the different films was evidenced by AFM, revealing that the roughness varied from 40 nm to 87 nm depending on the starting solution. The photoelectrochemical performance of the films was evaluated by chronoamperometry, revealing a strong anodic photocurrent and confirming their n-type semiconducting nature.