Galvanic contact deposition of CdTe from ammoniacal basic electrolytes at elevated temperatures using an autoclave-type electrolysis vessel

The galvanic contact deposition of CdTe layers from an ammoniacal basic electrolyte was carried out at a temperature range from 363 K (90 °C) to 423 K (150 °C) using an auto-clave type electrolysis vessel. The current densities at 363 and 393 K were almost the same level as that at 343 K under the dark condition, resulting in the deposition of near-stoichiometric CdTe layers on Au-plated Cu substrates, while the current density at 423 K was larger due to the codeposition of a Cd3Au phase. The mean crystallite size of the resulting CdTe layers was increased with the increase in the temperature of the electrolytes. The current density was enhanced by irradiating the cathode surface with visible light during the CdTe deposition and, in this case, the current efficiency was also dramatically increased. The layer obtained under illumination at 393 K consisted of near stoichiometric CdTe and a small amount of elemental Cd, while the layer prepared in the dark had a single phase CdTe. The mean crystallite size of the CdTe layer prepared at 393 K under illumination was about 24 nm.