Hexagonal cadmium chalcogenide thin films prepared by electrodeposition from near-boiling aqueous solutions

Thin, n-type, CdSe and CdSe,Te, _-x semiconductive films were prepared by cathodic electrodeposition onto titanium electrodes. An electrochemical cell was specially designed in order to perform electrodeposition in a near-boiling aqueous-ethyleneglycol bath at a temperature of approximately 110°C. The composition of the as-grown films, their crystal structure, morphology and band-gap width were studied as a function of the deposition potential and chalcogen ion concentration. It is shown that high temperatures have a positive effect on the crystal quality and the photoresponse stability of cadmium chalcogenide thin films even by employing electrolytes rather concentrated in selenous acid. Under specific conditions, a small shift in deposition potential brings about a complete phase transformation of the CdSe layers. In this manner, the described method enables the preparation of hexagonal CdSe deposits.