Deep-level transient spectroscopy, high-resolution Laplace deep-level transient spectroscopy and Laplace deep-level transient spectroscopy combined with uniaxial stress were used for the characterization and identification of electrically active defects induced in Sb-doped germanium crystals by irradiation with fast neutrons. The samples were irradiated with relatively small doses of neutrons (≤5 x 1011/cm2) in order to produce uniformly distributed damage and to detect small defect clusters. It was found that for such low neutron doses in many respects the damage produced was similar to that resulting from electron irradiation. Vacancy–antimony (V–Sb) pairs uniformly distributed in the sample bulk were the dominant defects observed in the deep-level transient spectra. It was inferred from the Laplace deep-level transient spectroscopic measurements under application of uniaxial stress that the V–Sb pair had a trigonal symmetry in the doubly negatively charged state. It was argued that an electron trap with the activation energy for electron emission of 0.1eV was related to an acceptor state of a small vacancy cluster located in highly damaged regions of the neutron-irradiated samples. Laplace deep-level transient spectroscopic measurements under application of uniaxial stress indicated that the symmetry of the defect was low, monoclinic-I, C1h point group, or lower. Environment-induced broadening of the Laplace deep-level transient spectroscopy signal due to this centre prevents precise determination of the defect symmetry.

Neutron-Irradiation-Induced Defects in Germanium - a Laplace Deep Level Transient Spectroscopy Study. I.Capan, B.Pivac, I.D.Hawkins, V.P.Markevich, A.R.Peaker, L.Dobaczewski, R.Jačimović: Vacuum, 2009, 84[1], 32-6