Defect states in ZnSe single crystals irradiated with gamma rays

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Abstract
Defect states in ZnSe single crystals induced by 60Co γ‐ray irradiation have been investigated with deep‐level transient spectroscopy (DLTS) and optical deep‐level transient spectroscopy (ODLTS). 5‐MeV‐electron‐irradiated crystals have also been examined for comparison. With DLTS measurements it is found that two electron traps at Ec − 0.27 eV and Ec − 0.49 eV are newly introduced, and the concentration of an electron trap at Ec − 0.30 eV, which exists in unirradiated ZnSe, is increased by γ‐ray or electron irradiation. Two additional electron traps located at Ec − 0.15 eV and Ec − 0.79 eV are also observed, and are unique to the γ‐ray and the 5‐MeV‐electron‐irradiated material, respectively. In ODLTS spectra a newly introduced hole trap at Ev+0.71 eV and the increase in the concentration of a trap at Ev+0.19 eV are observed in the ZnSe irradiated with γ ray or 5 MeV electron. It is concluded that the electron trap at Ec−0.30 eV and the hole trap at Ev+0.71 eV are attributed to a Se and Zn vacancy‐associated defect in the ZnSe single crystal, respectively. The hole trap at Ev +0.19 eV is tentatively identified as arising from an impurity Se vacancy complex.