The electrodeposition of CdSe from alkaline electrolytes

Polarization curves of CdSe electrodeposited from aqueous ammonia solutions containing selenosulfate and the EDTA complex of cadmium ions follow Tafel lines for current densities smaller than cathodic and anodic reaction limited current densities. Reaction orders for electrodeposition are one with respect to selenosulfate and zero with respect to cadmium ions. At high flow velocities of the electrolyte, only thin layers of CdSe are obtained. Very small effective diffusion coefficients determined from diffusion limited currents indicate diffusion into the electrolyte of a reaction product formed in an equilibrium reaction. Three-dimensional nucleation on the thin layer occurs at low flow velocities, A mechanism modeling the nucleation and growth kinetics is proposed, The Gibbs energy of formation of CdSe is calculated using measurements of the equilibrium potential of CdSe. (C) 2001 Elsevier Science Ltd. All rights reserved.