The properties of As antisite-related defects, in material which had been grown at low temperatures by means of molecular beam epitaxy, were compared with the properties of the EL2 defect in Czochralski-type material. This revealed some interesting similarities. First-principles molecular dynamics calculations were used to identify and study a low-energy nearest-neighbor complex, of an As antisite and an As interstitial, which exhibited many of the properties that were observed in the case of the predominant As antisite-related complex in GaAs that was grown or annealed at 300 to 400C. It could also explain the strong As antisite-like electron paramagnetic resonance signals which were observed in this material. This complex had a donor level which was 0.1eV higher in the gap than was the donor level of the isolated As antisite, and had a binding energy of about 0.5eV with respect to the isolated antisite and isolated interstitial. The shift from n-type to p-type behavior which was observed when low-temperature material was grown at 300 to 400C and annealed at higher temperatures, was attributed to the beginning of the break-up of this complex. However, the latter did not have a triply coordinated metastable state which could explain the metastable behavior which was observed in material which was grown at 400C.

J.I.Landman, C.G.Morgan, J.T.Schick: Physical Review Letters, 1995, 74[20], 4007-10