Effects of B and Ge codoping on minority carrier lifetime in Ga-doped Czochralski-silicon

Abstract

We investigated the effects of B/Ge codoping on the minority carrier lifetime in gallium (Ga)-doped Czochralski-silicon (CZ-Si) crystals. Minority carrier lifetime decreased from 28 to 0.1 μs when the B concentration was increased from 1×1015 to 1×1017 cm−3 in Ga/B codoped CZ-Si crystals. The minority carrier lifetime increased from 30 to 76 μs with increasing Ge concentration from 1×1017 to 2×1020 cm−3 in Ga/Ge codoped CZ-Si crystals. Light-induced degradation experiments showed that Ga/B codoped CZ-Si degraded rapidly, while Ga/Ge codoped CZ-Si showed no degradation. Moreover, the flow pattern defect density related to grown-in microdefects in as-grown Ga/Ge codoped CZ-Si decreased with increasing Ge concentration. The experimental results are explained using a defect reaction model based on the formation of Ge-vacancy-oxygen dimer complexes in the CZ-Si crystal during postgrowth cooling.