Nanostructuration and band gap emission enhancement of ZnO film via electrochemical anodization

• Synthesis of nanostructured ZnO films with good adhesion to the substrate
• The structural quality of the films has been improved.
• The band gap emission intensity of the films has been enhanced.

We report fabrication of nanostructured zinc oxide (ZnO) thin films with improved optical properties through electrochemical anodization. The ZnO films were produced over silicon substrates via radio-frequency (RF) plasma magnetron sputtering technique followed by electrochemical treatment in potassium sulfate solution. After electrochemical treatment, the effect of applied potential on the band gap emission behavior of ZnO films was investigated for the potential drop of 1.8, 2.4 and 3.0 V against reference electrode of Ag/AgCl/0.1 M KCl. Depending on these values, ZnO films with different degrees of nonporous morphology, improved structural quality and oxygen-rich surface chemistry were obtained. The treatment also resulted in enhancement of band gap emission from ZnO films with the degree of enhancement depending on the applied potential. As compared to the as-deposited films, a maximum increase in the photoemission intensity by more than 2.2 times was noticed. In this paper, any changes in the structure, surface chemistry and band gap emission intensity of the RF sputter deposited films, as induced by the anodization treatment at differential potential values, are discussed.