Impurity diffusion via an intermediate species: The B-Si system

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Abstract
Motion of a substitutional impurity via a fast-diffusing intermediate species is discussed. An analytical solution is given for the case of low impurity concentration. For short times, few atoms migrate and the solution behaves exponentially. We observe this exponential signature in the diffusion of nanometer-scale B-doping profiles in Si. The migration frequency during oxidation-enhanced diffusion is consistent with diffusion-limited knockout of an interstitial-type-B species. This is the first direct experimental evidence for dopant diffusion in Si via an intermediate species.