Ab initio prediction of dopant segregation at elemental semiconductor grain boundaries without coordination defects

We present results of an extensive state-of-the-art ab initio study of the segregation of dopants to the Σ=5 tilt (310) grain boundary in germanium. Despite the lack of reactive bond coordination defects in this boundary, we predict a significant tendency for n-type dopants to segregate to the boundary. Our results lead to a general theory of dopant segregation at tetrahedrally bonded semiconductor defects, where lattice relaxation effects are irrelevant and segregation is driven by the mixing of localized carrier states of the defect with the hydrogenic states of the dopant.