A dry vapor treatment ofCdCl2is being developed as an alternative approach to the conventional solutionCdCl2treatment of CdS/CdTe devices. In this alternative process, the CdS/CdTe substrates are vapor treated in a close-spaced sublimation configuration. A 16-run Plackett-Burman screening experiment identified source temperature, substrate temperature, and treatment time as being the most significant parameters in the process. Subsequently, a 20-run Central Composite Design showed that a source temperature of 380–390&hthinsp;°C, a temperature gradient (&Dgr;T) of 5&hthinsp;°C, and a time of 10 minutes provides the most process tolerant combination, yielding a total-area efficiency of 12.6&percent;. A strong interaction between &Dgr;T and treatment time was also identified. The model indicated that for a small &Dgr;T, device performance improved with decreasing time, whereas at larger values of &Dgr;T, performance increased with increasing time. ©1999 American Institute of Physics.