Surface Characterization of Electrochemically Fabricated CuO Doped ZnO Thin Film

Abstract

In this study, ZnO and CuO doped zinc oxide thin films were cathodically deposited in aqueous zinc chloride solutions in the presence of oxygen on a Pt/Ti/SiO2/Si substrate through an electrochemical reaction. A mercurous sulfate electrode was used as a reference electrode and the counter electrode was a Pt spiral wire. Deposition was carried out in solutions containing Zn2+ ions introduced as ZnCl2 salt at concentrations ranging from 5.0 x 10-4 to 5.0 x 10-2 M. The bath temperatures were controlled from 65°C to 80°C. The oxygen gas was introduced from argon/oxygen mixtures allowing its partial pressure to be fixed along with its concentration in the solution. Doping of CuO was carried out in cupric nitrate or a cupric chloride/0.1M KCl solution. The influence of the Cu/Zn concentration, deposition temperature of a solution, applied cathodic potential and deposition time were optimized. After the potential was applied, the cathodic current reached a steady state within 5 min. The composition, and the characterization of the surface of the films were investigated through X-ray diffractometry, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy.