Recombination parameters in low-resistivity gamma-irradiated η-type germanium

Abstract

Abstract Studies of recombination in ∼0.2 Ω-cm As- and Sb-doped Co60 γ-irradiated Ge which yield energy levels and the temperature dependence of the electron and hole capture probabilities are reported. For Sb-doped material at 323°K, the recombination center energy level position (neglecting statistical weight) was found to be 0.361±0.005 eV above the valence band with a possible slight temperature dependence corresponding roughly to one-half the variation of band gap with temperature. The capture probability ratio at this same temperature was 740. For the Asdoped case, two different levels appear to dominate the recombination process in annealed and unannealed low resistivity material. The energy level positions relative to the valence band (neglecting statistical weight) are 0.327±0.005 eV and 0.37±0.01 eV at room temperature for the annealed and unannealed samples, respectively. The corresponding capture probability ratios are 650 and 810. As in the case of Sb-doping, the energy level appears to shift with temperature at about one-half the rate of the shift in band gap energy.