The thermal stability and electronic properties of the vacancy–donor complexes, often referred to as the E centers, were studied in Si, unstrained Si–Ge and pure Ge. The E centers were introduced by electron irradiation or gamma rays. In Si, Laplace deep level transient spectroscopy was used to separate the E center emission from the di-vacancy, thus enabling very reliable data to be obtained for the vacancy complexes with P, As and Sb. In pure Ge only the E centers associated with P and Sb were reported and in Ge rich SiGe only V–P. In all the samples measured the thermal stability of V–Sb was found to be significantly higher than V–P. With regard to the energy levels, the activation energy of electron emission from the single-acceptor level of the E center in Si were for V–Sb 0.40eV and for V–P 0.46eV. For the pure Ge case, the single acceptor was a hole trap with emission to the valence band having energies for V–P of 0.35eV and V–Sb of 0.31eV. Similar values were found for Ge rich SiGe. The double-acceptor state was not seen in Si but in Ge produced a state with an activation energy for electron emission of 0.30eV for V–P and 0.38eV for V–Sb. This was also reflected in the Ge rich alloys of SiGe:P that were measured here.

The Vacancy–Donor Pair in Unstrained Silicon, Germanium and SiGe Alloys. A.R.Peaker, V.P.Markevich, F.D.Auret, L.Dobaczewski, N.Abrosimov: Journal of Physics - Condensed Matter, 2005, 17[22], S2293-302