Defect states, which were introduced into monocrystals by 60Co γ-irradiation, were investigated by using deep-level transient spectroscopy and optical deep-level transient spectroscopy. Some 5MeV electron-irradiated crystals were also examined for the purposes of comparison. By using deep-level transient spectroscopic measurements, it was found that 2 electron traps, at Ec-0.27eV and Ec-0.49eV, were new. The concentration of an electron trap at Ec-0.30eV, which existed in non-irradiated material, was increased by γ- or electron-irradiation. Two additional electron traps, which were located at Ec-0.15eV and Ec-0.79eV, were also observed, and were unique to γ-irradiated and 5MeV electron-irradiated material, respectively. A new hole trap (at Ev+0.71eV in optical deep-level transient spectroscopic spectra), and an increase in the concentration of a trap at Ev+0.19eV, were observed in material that was irradiated with γ-rays or 5MeV electrons. It was concluded that the electron trap at Ec-0.30eV, and the hole trap at Ev+0.71eV were due to Se and Zn vacancy-associated defects, respectively. A hole trap at Ev+0.19eV was tentatively attributed to an impurity Se vacancy complex.

M.Karai, K.Kido, H.Naito, K.Kurosawa, M.Okuda, T.Fujino, M.Kitagawa: Journal of Applied Physics, 1991, 69[1], 291-7