Silicon self-diffusion under extrinsic conditions

Self-diffusion in silicon is investigated under extrinsic carrier conditions by monitoring the diffusion of Si-30 in isotopically enriched silicon layers with boron and phosphorus background doping. At 1000 degreesC, we find that the Si self-diffusion coefficient is slightly enhanced in both n- and p-type backgrounds. This is direct evidence of the existence of both negatively and positively charged native point defects in Si. We use a simple model involving three charge states to explain the data, which yield the relative contributions of these charge states to the overall self-diffusion coefficient and the locations of the deep levels they introduce in the band gap. (C) 2001 American Institute of Physics.