Energy and Orientation Dependence of Electron-Irradiation-Induced Damage in Undoped GaSb

Undoped GaSb single crystals were irradiated at 77^∘{}K with electrons having energies betwen 0.23 and 1.00 MeV. The incident electron beam was aligned with either the [111] or the [1̄1̄1̄] direction of the sample. The isochronal recovery of the Hall coefficient and the electrical resistivity was measured after each irradiation. The positions and widths of the four major recovery stages were independent of the irradiation energy. The production rates of the defects corresponding to the four stages differed in their energy dependence. Their threshold electron energies were evaluated as 0.34 MeV for stage I, 0.17 MeV for stage II, 0.33 MeV for stage III, and 0.34 MeV for stage IV. Stage-I defect production was higher with the electron beam in the [111] direction than in the [1̄1̄1̄] direction. The reverse was the case for stage-II, -III, and -IV defect production. Stage I is attributed to the recovery of defects created by the displacement of single Sb atoms. The threshold displacement energy for Sb atoms is larger than 7.5 eV but smaller than 13.1 eV. Stage II is interpreted as recovery of defects produced by the displacement of single Ga atoms. The threshold displacement energy for Ga atoms is about 6.2 eV. It is suggested that stages III and IV represent the recovery of defects created by multiple displacement processes starting with the displacement of a Ga atom.