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

摘要

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 × 10~(15) to 1 × 10~(17) 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 × 10~(17) to 2 × 10~(20) 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.