Analysis for positions of Sn atoms in epitaxial Ge_1−xSn_x film in low temperature depositions

We investigated the position of Sn atoms in Ge_1−xSn_x film grown at a low temperature by using the Extended X-ray Absorption Fine Structure (EXAFS) method. Vacancies had been expected to be introduced near the growing surface vicinity of a Sn atom and located at a split-vacancy position due to the binding nature between a Sn atom and a vacancy, which was predicted by the calculation for a bulk model in the literature. However, the EXAFS showed that almost all Sn atoms were located at the substitutional position and did not form a split-vacancy. - Highlights: • Extended X-ray Absorption Fine Structure (EXAFS) study of epitaxial Ge_1−xSnx film • EXAFS shows that almost all Sn atoms are located at substitutional positions. • The amount of vacancies introduced in low-temperature epitaxial growth is small