Identification of electron-irradiation defects in semi-insulating GaAs by normalized thermally stimulated current measurements

Primary defects induced by 1 MeV electron irradiation have been quantitatively studied in semi-insulating (SI) GaAs by using normalized thermally stimulated current spectroscopy, a new technique. Defects identical to (or similar to) those known in the thermally stimulated current literature as T-6*(0.13 eV), T-5(0.34 eV), and T-4(0.31 eV) are produced at rates 0.70, 0.08, and 0.23 cm(-1), respectively; T-5 is also a strong trap in unirradiated SI GaAs. The defects T-6* and T-4 correspond closely to the irradiation-induced traps E2(0.14 eV) and E3(0.30 eV), studied extensively by deep-level transient spectroscopy and Hall-effect measurements and assigned to the As vacancy. We thus infer that traps T-6* and T-4 (and probably also T-5) in SI GaGs have As-vacancy character.