Synthesis and luminescence properties of electrodeposited ZnO films

Zinc oxide (ZnO) films have been grown on gold (111) by electrodeposition using two different OH⁻ sources, nitrate and peroxide, in order to obtain a comparative study between them. The morphology, structural and optical characterization of the films were investigated depending on the solution used (nitrate and peroxide) and the applied potential. Scanning electron microscopy pictures show different morphologies in each case. X-ray diffraction confirms that the films are pure ZnO oriented along the (0002) direction. ZnO films have been studied by photoluminescence to identify the emission of defects in the visible range. A consistent model that explains the emissions for the different electrodeposited ZnO films is proposed. We have associated the green and yellow emissions to a transition from the donor OH⁻ to the acceptor zinc vacancies (V_Zn⁻) and to interstitial oxygen (O_i⁰), respectively. The orange-red emission is probably due to transitions from the conducting band to O_i⁻ and O_Zn⁰ defects and the infrared emission to transition from these O_i^−/2− and O_Zn^0/− defects to the valence band.