GALVANIC DEPOSITION OF CADMIUM-SULFIDE THIN-FILMS

A technique is presented for the deposition of high quality cadmium su lfide (CdS) thin films onto SnO2 substrates by a galvanic method. Sing le phase films were deposited in a bath of cadmium chloride and sodium thiosulfate at pH = 4 and temperature = 85-degrees-C at a growth rate of 1 nm/min. In the pH range of 3 to 4, the deposition rate is sensit ive to cadmium chloride concentration. At higher pH the deposition rat e is very low while at lower pH mixed phase films were obtained and ho mogeneous CdS formation occurred in the bath. The structural and optic al properties of the CdS films are also presented and are comparable t o films deposited by other methods. CdS/CdTe solar cells with efficien cies over 8% were fabricated using evaporated CdTe to demonstrate the utility of CdS films deposited by this simple technique. The galvanic deposition technique is useful in laboratory settings with limited dep osition hardware and limited chemical waste disposal facilities.