Bistability-mediated carrier recombination at light-induced boron-oxygen complexes in silicon

A first-principles study of the BO2 complex in B-doped Czochralski Si reveals a defect-bistability-mediated carrier recombination mechanism, which contrasts with the standard fixed-level Shockley-Read-Hall model of recombination. An O-2 dimer distant from B causes only weak carrier recombination, which nevertheless drives O-2 diffusion under light to form the BO2 complex. Although BO2 and O-2 produce nearly identical defect levels in the band gap, the recombination at BO2 is substantially faster than at O-2 because the charge state of the latter inhibits the hole capture step of recombination.