Redox and solution chemistry of the SeSO₃ ^2--Zn-EDTA^2- system and electrodeposition behavior of ZnSe from alkaline solutions

The specific redox and solution chemistry involved in the formulation of the plating solution for the electrodeposition of zinc selenide from the SeSO₃^2-/Zn²⁺/EDTA system was investigated. After a theoretical analysis which allowed the electrodeposition conditions to be fixed, based on potential-pH and solubility diagrams, an experimental study was conducted by varying the deposition parameters (composition, pH, potential). XRD, EDS, AFM and reflectance measurements were used to characterize the structure, morphology, composition, and optical properties of films deposited on conducting glasses. EDS analysis showed that the as grown films are almost stoichiometric in a wide potential interval and also that the film thicknesses are lower than the values estimated from the circulating charge. The possible reasons for the latter behavior are discussed.