Erbium point defects in silicon

The possible technological importance of rare-earth-doped semiconductors has led to great interest in these materials. However, little at the atomic level is hitherto known about such defects in the host lattice. Using first-principles calculations, the nature of erbium point defects in crystalline silicon is investigated. The total energy of an erbium point defect at several high-symmetry sites and with two different oxidation states is computed. Among the configurations studied, the minimum-energy one is Er³⁺ at a tetrahedral interstitial site. The nature of the Er-related defect levels is determined.