Injection level dependence of the defect-related carrier lifetime in light-degraded boron-doped Czochralski silicon

The carrier recombination lifetime in light-degraded boron-doped 1 Ω cm Czochralski-grown silicon wafers is measured as a function of the bulk excess carrier concentration Δn. The measurements are performed with the quasi-steady state photoconductance method and cover a large injection level range between 1013 and 1.5×1017 cm−3. We observe a very strong increase of the carrier lifetime in the Δn range between 1014 and 2×1016 cm−3, which is attributed to boron–oxygen (BiOi) defect pairs. The observed strong increase of the defect-related carrier lifetime allows us to determine the previously unknown hole capture cross section σp of the BiOi pair. Our analysis gives a σp value of (0.45–1.2)×10−15 cm2, which is 2–3 orders of magnitude smaller than the corresponding electron capture cross section.