Lattice location study of ion implanted Sn and Sn-related defects in Ge

In this work, we present a lattice location study of Sn in Ge. From emission channeling experiments, we determined the exact lattice location of ion implanted $^{121}$Sn atoms and compared the results to predictions from density-functional calculations. The majority of the Sn atoms are positioned on the substitutional site, as can be expected for an isovalent impurity, while a second significant fraction occupies the sixfold coordinated bond-centered site, which is stable up to at least 400 °C. Corroborated by ab initio calculations, we attribute this fraction of bond-centered Sn atoms to the Sn-vacancy defect complex in the split-vacancy configuration. Furthermore, we are able to assign specific defect complex geometries to resonances from earlier Mössbauer spectroscopy studies of Sn in Ge.