Electronic structural details of donor–vacancy complexes in Si-doped Ge and Ge-doped Si

We present a detailed picture of the electronic structure of donor–vacancy complexes in Ge-doped silicon and Si-doped germanium clusters to mimic Si-rich and Ge-rich SiGe alloys, respectively. Jahn-Teller effects and electrical levels were investigated in both Si-rich and Ge-rich end compositions. It is shown that while Ge atoms act as efficient traps for mobile E-centers in Si-rich alloys, Si atoms in Ge-rich material do not have this ability. A detailed linear combination of atomic orbitals model is proposed for VP–Ge and VP–Si complexes in Si1−xGex and Ge1−xSix, where the orbital filling order is driven by the larger electron affinity of Si atoms when compared to Ge.