Investigation of Nucleation and Growth Mechanism of Bi-Doped ZnO Electrodeposited on ITO Substrate

Abstract

The Bi-doped zinc oxide (Bi-ZnO) nanostructured was elaborated on the indium-doped tin oxide (ITO) substrate by electrodeposition. The bath temperature was performed at 70°C. The films were cathodically electrodeposited in a bath containing 0.01mol.L-1 Zn(NO3)2. 6H2O, while the source of doping is Bi(NO3 )3. 5H2O and 0.1 mol.L-1 KNO3 was used as supporting electrolyte. Our interest is to study the influence of doping on the mechanism of electrodeposition and the structural and optical properties of these layers. The cyclic voltammetry and chronoamperometry investigation shows that the electrodeposition of ZnO and Bi ZnO doped at a negative potential around −1.1 V versus Ag/AgCl is a quasi-reversible reaction controlled by the diffusion process. Current transient curves measured showed that the nucleation mechanism of ZnO and Bi-doped ZnO is instantaneous with three-dimensional growth of hemispherical nuclei. XRD patterns show that ZnO and Bi-doped ZnO on the ITO substrate crystallizes in a hexagonal würtzite-like structure. UV-Visible transmission spectrum affirms that good transparent films of Bi-doped ZnO cannot be obtained. SEM analysis revealed that the morphology of the obtained deposits depends on the type of electrodeposition mechanism.