Electrodeposited stoichiometric zinc sulfide films

Zinc sulfide (ZnS) thin films were obtained by electrodeposition on Hartford glass substrates using reduction potentials from −650 to −560 mV (vs. SCE), with a deposition time of 1000 s. The ZnS thin films were characterized after the annealing process using UV–Vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), under two atm, inert gas and sulfur gas, at two temperature conditions (150 and 250 °C). The ZnS thin films showed a hexagonal, homogeneous and uniform structure in the wurtzite phase with a band gap ranging from 3.71 to 3.82 eV. The morphology remained unchanged when the electrodeposition potential or the annealing temperature was varied. We obtained Zn/S ratio values of ~1 for the ZnS thin films under a sulfur atmosphere and under an inert atmosphere treated at 150 °C. The properties of the deposited ZnS thin films make them suitable for the development of photovoltaic devices based on Cu2ZnSnS4, either as a buffer layer in the back contact or as a precursor layer.