Analysis of the mechanism for electrodeposition of the ZnSe phase on Cu substrate

Electrodeposition mechanism of selenium, zinc and ZnSe phase was studied with the electrochemical techniques. The chronoamperometry and voltammetry were combined with quartz crystal microbalance technique to analyse the deposition processes. It was found that they strongly depend on the applied potentials. The deposition of pure Se starts at 0 V vs. saturated calomel electrode (SCE) and the efficiency of this process decreases due to H2Se formation and hydrogen evolution when the more negative potentials are reached. The voltammetric and microgravimetric measurements suggest that the deposition of Zn from the bath containing both ions, follows selenium deposition and synthesis of ZnSe is initiated at −0.6 V vs. SCE. The chronoamperometric transients combined with microgravimetry confirmed the range of potentials in which Se and ZnSe are deposited. Below −0.84 V vs. SCE the formation of H2Se was observed. Then H2Se may react with Zn2+ ions and another mechanism of ZnSe synthesis is possible.