Vacancy-Impurity Complexes in Highly Sb-Doped Si Grown by Molecular Beam Epitaxy

Abstract

Positron annihilation measurements, supported by first-principles electron-structure calculations, identify vacancies and vacancy clusters decorated by 1–2 dopant impurities in highly Sb-doped Si. The concentration of vacancy defects increases with Sb doping and contributes significantly to the electrical compensation. Annealings at low temperatures of 400–500 K convert the defects to larger complexes where the open volume is neighbored by 2–3 Sb atoms. This behavior is attributed to the migration of vacancy-Sb pairs and demonstrates at atomic level the metastability of the material grown by epitaxy at low temperature.