High-quality Mc-Si wafers for high efficiency solar cells

High purity feedstock was used by ScanWafer to make high-quality mc-Si wafers. These wafers were characterized in detail by ECN and UKON. The initial lifetime of minority carriers over the ingot varied from about 10 to about 100 μs. The interstitial oxygen and substitutional carbon concentrations are below 10 ppma and that low concentration will hardly affect the lifetime in the material and the solar cell output. Standard firing-through SiNx:H cell processing resulted in efficiencies from 15 to 16%. Advanced in-line processing resulted in an maximum efficiency of 16.5%. The lifetime after cell processing was 75-150 μs. Modelling shows that this lifetime hardly limits the efficiency and efficiencies above 17% are possible.