abstract
Today’s industry-standard B-doped monocrystalline silicon still suffers from light-induced degradation (LID) of the carrier lifetime. Illumination at elevated temperatures leads to a so-called regeneration, i.e. a recovery of both the carrier lifetime and the solar cell efficiency. However, even though the carrier lifetime on test wafers increases from about 1ms after processing to 3ms after regeneration, the corresponding PERC+ cell efficiencies in both states are identical; possible reasons for this discrepancy are discussed in this paper. Additionally, B-doped Czochralski silicon wafers with an ultralow oxygen content of 2.6 ppma are evaluated, as well as industrial Ga-doped wafers. Both wafer materials are completely LID free, as demonstrated in lifetime measurements and PERC+ cell efficiencies, and enable up to 0.4%abs. higher efficiencies than current industry-typical boron-doped wafers.