Dopant-assisted Concentration Enhancement of Substitutional Mn in Si and Ge

Incorporation of Mn atoms as magnetic impurities in bulk Si and Ge is of great importance for integrating magnetism with existing device technology. Here, we study the influence of p- and n-type electronic dopants on Mn incorporation in bulk Si and Ge, using first-principles calculations within density functional theory. We find that in bulk Si, the site preference of a single Mn atom is changed from interstitial to substitutional in the presence of a neighboring n-type dopant (P, As, Sb). In bulk Ge, a Mn atom is more easily incorporated into the lattice when an n-type dopant is present in its immediate neighborhood, forming a stable Mn/dopant dimer with both impurities at substitutional sites. A detailed analysis of magnetic exchange interactions between such dimers reveals that magnetic properties are not degraded when Mn atoms coexist with n-type dopants.