EXPERIMENTAL-EVIDENCE FOR A DUAL VACANCY INTERSTITIAL MECHANISM OF SELF-DIFFUSION IN SILICON

Epitaxially grown isotopically enriched Si layers have been used to st udy self-diffusion in Si directly at the temperatures of 1000 and 1100 degrees C. We obtain equilibrium diffusion coefficients in accordance with previous experiments and theoretical calculations. Comparison of diffusion data of self-, antimony, and phosphorus diffusion in Si und er identical conditions of perturbed self-interstitial and vacancy con centrations created by surface reactions enables us to determine the m icroscopic mechanisms of Si self-diffusion. We find that, in this temp erature range, self-interstitials contribute roughly 2/3 to Si self-di ffusion, and vacancies 1/3, with the concerted exchange component bein g less than 14%. This constitutes direct experimental evidence that, o n the atomic scale, self-diffusion in Si is mediated both by self-inte rstitials and vacancies. (C) 1998 American Institute of Physics.