Electronic structure of molecular-beam-epitaxy growth-induced defects in GaAs

The electronic properties of molecular-beam-epitaxy growth-induced defects in GaAs are investigated through a detailed analysis of the 1.504--1.511-eV defect-bound excitons with use of low-temperature photoluminescence, polarization studies, and excitation spectroscopy. It is shown that transfer processes are selective between several high-energy excited states and the low-lying ones, allowing to distinguish at least four sets of bound-exciton complexes related to distinct defect centers. The splitting patterns of the various bound-exciton systems are quantitatively analyzed in the framework of excitons bound to neutral associates, taking into account both J-J coupling and local-field effects. An isoelectroniclike defect model is found to be most consistent with the large splittings in the bound-exciton complexes, the short-range hole-attractive potential of the involved defects, and the angular momentum J=0 in the final states of the related transitions.