Irradiation-induced defects in Ge studied by transient spectroscopies

Irradiation-induced impurity-point defect complexes have been investigated in n-type germanium crystals that were doped with either antimony or oxygen. Several majority-carrier traps and one minority-carrier trap are characterized by means of deep-level transient spectroscopy and minority-carrier transient spectroscopy. The antimony-vacancy complex $(E$ center) E0.37 is found to anneal in a way that is fundamentally different from that in silicon, since it is retarded under reverse bias. Temperature-dependent carrier capture cross sections of the E center are an order of magnitude lower than those of the oxygen-vacancy complex $(A$ center) E0.27 (σₙ~1.5×10^-18 and 2×10^-17 cm², respectively). A trap E0.23 which is antimony related grows in at room temperature, seemingly by interstitial capture. A trap E0.29 is assigned to the divacancy, since it is observed after proton irradiation but not after electron irradiation. A minority-carrier trap H0.30, displaying a strong Poole-Frenkel effect, is Sb related and possibly related to the E center. In view of the experiments, we comment on a range of diverging results in the literature.