Investigation of optical properties of zinc oxide nanofilms deposited by electrodeposition technique

Abstract

Zinc oxide (ZnO) nanofilms were synthesized by electrochemical deposition from a simple aqueous zinc chloride onto indium tin oxide (ITO) substrate. Chronoamperometry experiments were performed to deposit nanofilms at the cathodic potential −1.0 V and time 5000 s at 70°C. Diffraction measurements of x-ray showed the hexagonal wurtzite structure of the as-grown nanofilms and the preferred orientation was along the (002) axis. A well-defined ZnO morphology was generated under −1.0 V for 1000 s on ITO glass. Atomic force microscopy observations explored the effect of electrode coating technique on the microscale ZnO nanofilms. The optical constants and thickness of nanofilms were determined with high precision using spectroscopic ellipsometry. The measurements of photoluminescence demonstrated two emission peaks; the first of which was related to excitonic emissions at about 392 nm, referring to the band gap of ZnO, and the second was related to oxygen vacancies ionized singly at about 490 nm.