High-resolution spectroscopy of defect-bound excitons and acceptors in GaAs grown by molecular-beam epitaxy

New results on the groups of luminescence lines arising from defect-bound excitons and defect-complex acceptors in GaAs grown by molecular-beam epitaxy are reported. Both series of spectra are found to be polarized, thus establishing a strong link between them. Resonantly excited two-hole satellites of the defect-bound excitons are observed, supporting their identification as arising from exciton recombination at axial acceptor centers. Calculation of acceptor binding energies from the two-hole satellite displacements leads to reasonable agreement with those found from the electron to shallower defect-complex acceptor bands, providing a further clear connection between the two sets of bands.