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

Abstract

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 Si, the site preference of a single Mn atom is reversed from interstitial to substitutional in the presence of a neighboring n-type dopant (P, As, Sb). In Ge, a Mn atom is more readily incorporated into the lattice when an n-type dopant is present in its immediate neighborhood, forming a stable Mn/dopant pair with both impurities at substitutional sites. A detailed analysis of the magnetic exchange interactions between such pairs reveals a dramatic enhancement in the anisotropy of the magnetic coupling within the systems.