Atomic model for the EL0 defect in GaAs

We propose atomic models for the stable and metastable configurations of the bi-stable, oxygen-related defect in GaAs known as EL0. They consist of an O on As site donor as a nearest neighbor to a divacancy for the stable configuration and an O on Ga site acceptor between two As vacancies for the metastable configuration. We discuss analogies and distinctions between EL0 and EL2, another important bi-stable complex. We suggest that this complex is prominent in O-containing GaAs because divacancies migrate relatively rapidly and so are prone to formation of complexes.