Effect of Low Temperature Electron-Irradiation on the Electrical Properties of Undoped GaSb

Undoped GaSb samples were irradiated at 15°K and 80°K with 0.5 MeV and 1.0 MeV electrons. The effects of the irradiation on the temperature dependence of the Hall coefficient RH and the Hall mobility μH were investigated and a study of the recovery of the radiation-produced changes of these properties was made. After irradiation the Hall coefficient curves in a log RH vs T-1 diagram exhibit a maximum at low temperatures which indicates impurity conduction resulting from radiation-produced defects. At higher temperatures where the normal conduction mechanism is predominant the sign and magnitude of the radiation-produced changes of the Hall coefficient depend in a complex manner on measurement temperature, irradiation dose and irradiation energy. The Hall coefficient data obtained after small irradiation doses provide evidence that both acceptors and donors are produced by the irradiation. Donor production appears to be more pronounced at 1.0 MeV than at 0.5 MeV. At low temperatures the reciprocal Hall mobility has a tendency to vary stronger than linear with increasing irradiation dose. The dependence of the change of the reciprocal Hall mobility on the measurement temperature indicates that a substantial fraction of the radiation-produced defects act as neutral scattering centers. Recovery between 15 and 390°K occurs in four major stages which are located near 124, 168, 210 and 360°K. Acceptors are removed in all four stages. Evidence for the removal of donors is found only for stage IV.