Defects Related to Sb-Mediated Ge Quantum Dots

We report on a specific defect, which may form during the growth of Stranski-Krastanov surfactant-mediated Ge/Si (100) islands. Transmission electron microscopy reveals that these loop-like defects are local and could be represented by a missing plane of Ge atoms inside some of Ge islands. This specific defect may generate an electrically active trap within the Si band gap at about 0.3 eV above the Si valence band edge. Deep level transient spectroscopy reveals that at least 1 % of Ge islands may include such defects.