Can hydrogenation mitigate Cu-induced bulk degradation in silicon?

Abstract

Many defects can cause significant bulk degradation in crystalline silicon, which inherently limits solar cell efficiency. Perhaps the most well-known source of light-induced bulk degradation (LID) in Czochralski-grown silicon is the boron-oxygen defect. However, metal impurities, such as copper, can also cause severe degradation. Advanced hydrogenation processes incorporating minority carrier injection can effectively passivate boron-oxygen complexes, but their effect on copper-induced degradation has not been studied previously. Herein, we explore the effect of hydrogenation on LID in copper-contaminated silicon. Without hydrogenation the bulk lifetime decreases down to 5\ \mu\mathrm{s} while in hydrogenated samples the bulk lifetime remains above 300\ \mu\mathrm{s} during the whole degradation cycle. The results thus indicate that even in heavily copper-contaminated silicon hydrogenation can passivate Cu precipitates and mitigate Cu-LID.