アンモニア-アルカリ性水溶液からのCdTe電析におよぼすアンモニア濃度の影響

抄録

Electrodeposition of CdTe film from ammonia-alkaline aqueous solutions with different ammonia concentrations, [NH₃]_total=2.0-5.0mol dm^-3, was studied and deposition behavior at -0.70V vs SHE is discussed using a potential-pH diagram of the Cd-Te-NH₃-H₂O system in terms of underpotential deposition, where the deposition of Te atoms is followed by a rapid adsorption and reduction of Cd (II) species to form CdTe We found that the composition of the resulting film is controlled by ammonia concentration as well as by the pH and Cd (II)/Te (IV) concentration ratio, as previously been studied. The cadmium content of the resulting film increases with decreasing ammonia concentration of solutions An electrolyte with a Cd (II)/Te (IV) concentration ratio of 1, for example, gave a tellurium-rich deposit with low crystallinity under [NH₃]_total of 5.0mol dm^-3, while that with the same Cd(II)/Te(IV) ratio gave almost stoichiometric CdTe under [NH₃]_total of 3.0mol dm^-3