Electrodeposition of CdTe from Basic Aqueous Solutions Containing Ethylenediamine

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Abstract
Potentiostatic cathodic electrodeposition of CdTe on gold substrate was studied using basic aqueous electrolytic baths in which Cd(II) and Te(IV) species were dissolved to form Cd(en)32+Cd(en)32+ and TeO32−TeO32− ions, respectively (en: ethylenediamine). The stoichiometry of electrodeposited CdTe can be controlled by changing the Cd(II)/Te(IV) concentration ratio, pH, and/or the ethylenediamine content of the baths. Differences in the deposition behavior between two basic media with different complexing agents, ethylenediamine and ammonia, were discussed thermodynamically with potential-pH diagrams drawn for the Cd­Te­en­H2OCd­Te­en­H2O and the Cd­Te­NH3­H2OCd­Te­NH3­H2O systems. All the deposits with near stoichiometric composition prepared at −0.70 V vs. standard hydrogen electrode had a flat and smooth morphology. The use of ethylenediamine instead of ammonia made it possible to raise the temperature of electrolytic baths to 363 K, resulting in highly crystalline CdTe deposits without any post-treatment under a wide range of experimental conditions. © 2001 The Electrochemical Society. All rights reserved.