Monocrystalline semi-insulating substrates, implanted with 70MeV 56Fe ions to fluences ranging from 5 x 1012 to 1014/cm2, were investigated by optical transmission over the photon-energy range of 0.1 to 1.4eV. The density of radiation-induced defect states exhibited a considerable increase for fluences above 5 x 1013/cm2. Annealing studies of a sample subjected to a fluence of 1014/cm2 showed that significant damage recovery occurred at 100 to 500C; with an activation energy for annealing of 0.19eV. The mid-gap defect states were annealed out more rapidly than the near-bandedge defect states during annealing at up to 350C. The near-bandedge defect states annealed out more rapidly than mid-gap defect states during annealing at between 350 and 600C.

Dose Dependence and Annealing Behaviour of Radiation-Induced Defects in 70MeV 56Fe Implanted GaAs. M.M.Belekar, K.V.Sukhatankar, A.M.Narsale, G.Nair, B.M.Arora, D.Kanjilal: Radiation Measurements, 2003, 36[1-6], 681-4