Schottky barriers formed by depositing Au onto n-type Ge were used to study the Sb-vacancy complex (E center). Both hole and electron transitions were observed because the formation of an inversion layer at the semiconductor surface permitted minority carriers to be injected when the Schottky barrier was forward-biased. It was argued that the E center in Ge had 3 charge states: doubly negative, single negative, and neutral. The free energy of electron ionization for the double acceptor level of the complex was found to be ΔG(=/–) = 0.294–4.2kT(eV). Consequently, the position of the double acceptor level of the E center {E(=/–) = Ec– ΔG(=/–)} was temperature-dependent. In moderately Sb-doped (1013 to 1015/cm3) Ge crystals under equilibrium conditions, half-occupancy of the double acceptor state of the Sb-V complex occurred when the Fermi level was at about Ec–0.20eV. The single acceptor level of the E center was in the lower part of the band-gap. The activation energy of hole emission from the E(–/0) level was determined to be 0.307eV. The introduction of one Sb-V defect resulted in the removal of 3 free electrons in Sb-doped Ge.

Electronic Properties of Antimony-Vacancy Complex in Ge Crystals. V.P.Markevich, A.R.Peaker, V.V.Litvinov, V.V.Emtsev, L.I.Murin: Journal of Applied Physics, 2004, 95[8], 4078-83