Suppressed diffusion of boron and carbon in carbon-rich silicon

Transient enhanced diffusion of boron in silicon can be suppressed by substitutional carbon. We show here that diffusion of boron and carbon is strongly reduced in carbon-rich silicon, even when no supersaturation of interstitials due to implantation is present. Pronounced non-Fickian diffusion behavior was found for epitaxially grown-in carbon at concentrations well above its solid solubility. The experimentally observed suppression of B and C diffusion at high C concentrations is explained in terms of a recently proposed model that predicts an undersaturation of Si self-interstitials caused by diffusion of C out of C-rich regions.