Relationship between thermal treatment conditions and minority carrier lifetimes in p-type, FZ Si wafers

Minority-carrier lifetimes in FZ-p Si wafers were evaluated at various thermal treatments to investigate the effect of the recombination centers. Bulk lifetimes became longer in the case of annealing in O2 ambient at around 1000°C, while it decreased drastically in N2 and Ar ambients. Both N2 annealing sample and oxidation sample after N2 annealing were measured using deep level transient spectroscopy. Deep levels related to nitrogen defect were observed for the N2 annealing sample. However, no deep level was observed for the oxidation samples. These results suggest that recombination of minority carriers in the bulk occurred at deep levels related to the nitrogen-vacancy complex.