CdS/Cu$_x$s solar cells were prepared by immersing sintered layers of CdS in a hot aqueous solution containing cuprous ions.
The effects of varying periods of dipping and annealing on the photovoltaic properties of the heterojunctions were investgated.
The cell characteristics were improved by heat treatments in N$_2$ gas at 230℃, but prolonged annealing had deleterious effects on the devices. The optimum dipping was for a period of 1 min. and this produced a cell with a short-circuit current of 7.9 mA/㎠. The stoichiometry of Cu$_x$s layers is thought to be responsible for lower short-circuit current when the duration of dipping was short.
Heat treatment of the CdS films in H$_2$-atmosphere at 400℃ reduced sheet resistance, but decreased short-circuit current.
Fill factors and open-circuit voltages were strongly influenced by changes in shunt resistance which depended on dipping time and annealing time.
It was noticed that the sheet resistances of CdS layers in the cells were reduced with annealing time. Differences in short-circuit currents are qualitatively explained as due to the variation in defect density as controlled by the dipping period, annealing time, and by heat treatment of CdS layers.
