An electron-trapping defect level associated with the 235K annealing stage in electron-irradiation n-GaAs

Abstract

The authors report measurements by deep-level transient spectroscopy (DLTS) and immobile-space-charge profiling on lattice-defect production in VPE n-GaAs at 80K by 1.0 MeV electron irradiation, and on the annealing behaviour of the defects at 80-300K. It is shown that the electron traps E1, E2 and E3 are produced by the irradiation, before anneal at 300K, and that an additional electron-trapping defect 'E(0.23)', with an apparent activation energy of 0.23+or-0.02 eV to the conduction band, is created by the irradiation and is removed in the 235K annealing stage found previously by Thommen (1970) in electron-irradiated bulk-grown n-GaAs. The authors suggest that the E(0.23) level arises from a plural-defect structure, and that it anneals by dissociation or internal recombination. The results also indicate the irradiation production of below-mid-gap electron-trapping levels at a concentration much larger than the concentration of electron traps observed, as DLTS levels, in the upper half of the energy gap, and that about 50% annealing of the total net electron trap concentration occurred at 80-300K. Increased at 80-300K in the concentrations of the E1 and E2 defects were also observed in this range of annealing temperature.