Transition Metal Impurities on the Bond-Centered Site in Germanium

S. Decoster, S. Cottenier, B. De Vries, H. Emmerich, U. Wahl, J.G. Correia, A. Vantomme
Physical Review Letters
102 (6), 065502


We report on the lattice location of ion implanted Fe, Cu, and Ag impurities in germanium from a combined approach of emission channeling experiments and ab initio total energy calculations. Following common expectation, a fraction of these transition metals (TMs) was found on the substitutional Ge position. Less expected is the observation of a second fraction on the sixfold coordinated bond-centered site. Ab initio calculated heats of formation suggest this is the result of the trapping of a vacancy by a substitutional TM impurity, spontaneously forming an impurity-vacancy complex in the split-vacancy configuration. We also present an approach to displace the TM impurities from the electrically active substitutional site to the bond-centered site.