Vacancy interactions in GaAs

Abstract
Isochronal annealing of zinc- or silicon-doped GaAs as well as undoped semi-insulating or low-resistivity materials has been investigated by positron lifetime measurements. For impurity concentrations larger than 4.5×1017 cm−3, only monovacancy complexes such as ZnGaVAs, SiAsVGa, or AsGaVGa are observed and they yield a positron lifetime of 265±5 ps. For impurity concentrations less than 1×1017 cm−3, divacancies dominate and yield a lifetime of 295±5 ps. The concentrations of grown-in vacancies, either VAs or VGa, are both estimated to be in the range of (1–4)×1017 cm−3.