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The low "environmental-load" CdS/CdTe solar cells for reducing consumption of Cd compounds have been investigated employing the CdS layers fabricated at various substrate temperatures, T/sub CdS/. The nanostructure of CdS crystallites made at different T/sub CdS/ are compared to the crystallinity of CdS, and CdTe deposited on CdS as well as sulfur fraction in CdTe/sub 1-x/S/sub x/ mixed crystal layer unintentionally formed at CdS-CdTe(S) interface. To obtain relative high V/sub oc/, high crystallinity is required for CdS, while to prevent the degradation of CdS/CdTe(S) interface for keeping high FF, rather CdS with low crystallinity is suitable. To break the contradictional requirements for CdS crystallinity, a novel technique is introduced, i.e., (CH/sub 3/)/sub 2/SnCl/sub 2/ (DMTC) doping into CdS. The large sulfur fraction in CdTe/sub 1-x/S/sub x/ mixed crystal layer being a degree of the CdS/CdTe(S) interface is obtained in the solar cell employing the CdS layer doped with DMTC even when the DMTC-doped CdS layer obtains high crystallinity. So far, we have achieved 14.8% efficiency of the low environmental-load CdS/CdTe solar cell.