Structure and composition of amorphous Ge1−xSnx thin films

The composition and bonding configuration of amorphous germanium-tin (a-Ge1−xSnx) thin films are reported (0≤x<0.3). Mössbauer spectroscopy analyses show that under the reported deposition conditions all tin atoms enter the a-Ge network in a perfect substitutional way, i.e., in a covalent tetrahedral configuration. The absence of defect structures in the tin sites is discussed and compared with results on films prepared under different conditions.