A deep-level donor state with a signature that was similar to the EL6 level in molecular beam epitaxial material, when grown at 250C and annealed at temperatures ranging from 310 to 370C, was studied. The annealing kinetics of this level suggested the occurrence of confined pair recombination. A correlation was found between observed deep levels and published photoluminescence data on molecular beam epitaxial material which had been grown at low temperatures. The annealing data could be explained in terms of first-order annealing kinetics of the relevant defect involved, with an annealing enthalpy of 1.65eV. An interaction between Ga vacancies and As interstitials could explain the formation and removal of the observed level. The annealing behavior of the deep donor, and its assignment to EL6, was strongly related to the pair defect, VGa-Asi, as predicted on the basis of the 0.8eV photoluminescence emission from GaAs which was grown at low temperatures.

J.Darmo, F.Dubecý, P.Kordoš, A.Förster: Applied Physics Letters, 1998, 72[5], 590-2