The nature of boron‐oxygen lifetime‐degrading centres in silicon

Light‐induced degradation of minority carrier lifetime in silicon is caused by the formation of two B‐O recombination centres: fast‐stage centres (FRC) and slow‐stage centres (SRC). FRC were concluded to emerge by a carrier‐assisted reconfiguration of a latent BO 2 defect composed of a substitutional boron atom and an oxygen dimer. The nature of SRC however remained uncertain; this defect appeared to involve an interstitial boron atom rather than a substitutional one. More recent data on SRC in boron‐containing compensated p‐Si and n‐Si now show that the SRC actually emerge in the same way as FRC: by a reconfiguration of BO 2 , but from a different latent form. The two latent BO 2 defects (the precursors for FRC and for SRC) are created during a cooling stage after the last high‐temperature anneal, and their concentration, proportional to the boron concentration and squared oxygen concentration, depends on the cooling rate. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)