Effective lifetimes exceeding 300 μs in gettered p-type epitaxial kerfless silicon for photovoltaics

Abstract

We evaluate defect concentrations and investigate the lifetime potential of p-type single-crystal kerfless silicon produced via epitaxy for photovoltaics. In gettered material, low interstitial iron concentrations (as low as (3.2 ± 2.2) × 10[superscript 9] cm[superscript −3]) suggest that minority-carrier lifetime is not limited by dissolved iron. An increase in gettered lifetime from <20 to >300 μs is observed after increasing growth cleanliness. This improvement coincides with reductions in the concentration of Mo, V, Nb, and Cr impurities, but negligible change in the low area-fraction (<5%) of dislocated regions. Device simulations indicate that the high bulk lifetime of this material could support solar cell efficiencies >23%.