Abstract
Potentiostatic catholic electrodeposition of CdTe on gold-plated substrate was studied at 700°C or more using basic aqueous electrolytic baths in which Cd (II)-and Te (IV) -species were dissolving to form Cd (dien)22+ and TeO32- ions, respectively (dien: diethylenetriamine). The stoichiometry of CdTe electrodeposited can be controlled by changing the Cd (II)/Te (IV) concentration ratio, pH, and/or the diethylenetriamine content of the baths. Differences in the deposition behavior between two basic media with different complexing agents, diethylenetriamine and ammonia, were discussed thermodynamically with potential-pH diagrams drawn for the Cd-Te-dien-H2O and the Cd-Te-NH3-H2O systems. The deposition mechanism was also discussed in terms of interionic interaction between Cd (II) and Te (IV) species. The use of diethylenetriamine instead of ammonia made it possible to raise the temperature of electrolytic baths to 90°C, resulting in highly crystalline CdTe deposits without any post-treatment under a wide range of experimental conditions.
