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 ${}^{121}\text{S}\text{n}$ 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 $400°\text{C}$. 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.

• Received 13 January 2010

DOI:https://doi.org/10.1103/PhysRevB.81.155204