Abstract
A shallow acceptor-like defect labeled “A” is frequently incorporated in molecular beam epitaxial GaAs. We report here anomalous photoluminescence effects that are induced by this defect. With increasing concentration of the “A” defect: (1) neutral and ionized donor-bound exciton peaks disappear almost completely even for donor concentration as high as 7×1014 cm-3 and compensation ratio ND/NA≈0.3; (2) a new, sharp line emerges at 1.5138 eV, and (3) the relative intensity and line shape of the free exciton transition change dramatically. These observations are discussed in the perspective of previous reports, where similar effects were, in our opinion, misinterpreted.