Vacancies and E-centers in silicon as multi-symmetry defects

In this paper, using first-principles calculations, we demonstrate that vacancies and E-centers (AsV, SbV) in silicon can co-exist in several metastable configurations with notably different relaxation patterns, which have very similar formation energies. Thus these vacancy-type defects can be considered as multi-symmetry defects in the sense that, at elevated temperatures, the probabilities to find vacancies in different stable configurations are comparable. From an experimental point of view, the co-existence of various symmetries can complicate the identification of the defect.