Cd Cl 2 treatment, S diffusion, and recombination in polycrystalline CdTe

Time-resolved photoluminescence measurements on $\text{glass}∕\mathrm{Sn}{\mathrm{O}}_2∕\mathrm{Cd}\mathrm{Te}$ and $\text{glass}∕\mathrm{Sn}{\mathrm{O}}_2∕\mathrm{Cd}\mathrm{Te}∕\mathrm{Cd}\mathrm{S}$ structures indicate that the $\mathrm{Cd}{\mathrm{Cl}}_2$ process, without any S present, significantly reduces recombination. However, S diffusion is required for lifetimes comparable to those observed in high-efficiency solar cells. Low-temperature photoluminescence, cathodoluminescence, and scanning electron images indicate how defect chemistry, grain-boundary passivation, and morphology are affected by S diffusion and the $\mathrm{Cd}{\mathrm{Cl}}_2$ treatment.