Single crystals of n-type and p-type material which had been bombarded with 30MeV protons or 4MeV  particles at 77K were studied by means of deep-level transient capacitance spectroscopy. The bombardment was performed with or without a bias voltage. In the case of n-type material which had been grown by using the Czochralski method, familiar centers were accompanied by defects (E1, E2) with energies at Ec - 0.22eV and Ec - 0.25eV. These defects were observed only during bombardment in the presence of a bias voltage. Annealing out of the E2 defects raised the concentration of A centers (V-0). In the case of samples which had been grown by float-zoning, there were electron levels, EA1 (Ec - 0.15eV) and EA2 (Ec - 0.29eV), in equal concentrations. These 2 levels annealed out simultaneously, with an activation energy of 0.28eV. In the case of n-type Ge-doped material, some corresponding levels were observed. These were EG1 and EG2, with energies at Ec - 0.22eV and Ec - 0.4eV. The properties of the EA and EG defects suggested that they were doubly-charged acceptors. The results indicated that the E1, E2, EA and EG defects were of vacancy type. A vacancy which was stabilized by O (E2), C (EA) or Ge (EG) was proposed. In the case of p-type Ge-doped material, some H5 levels were observed which had electrical properties that were similar to those of V(++/+) defects. The annealing kinetics made it possible to associate the H5 centers with V-Ge defects. During annealing, the conversion of H5 centers into new h6 centers was observed.

K.A.Abdullin, B.N.Mukashev: Fizika i Tekhnika Poluprovodnikov, 1995, 29[2], 335-45 (Semiconductors, 1995, 29[2], 169-74)