Magnetic-Field-Induced Energy Shifts of the Ground State of Bound Excitons in GaAs

Abstract

We present photoluminescence measurements on bound excitons in Sn- and Cu-doped epitaxial GaAs in magnetic fields up to 12 T. The bound-exciton lines split; the shift towards higher energies of the center of gravity is identical for both dopants, despite their largely differing binding energies. The magnitude of the shift is comparable to that of the free exciton. A theoretical explanation assuming a short-range exciton-acceptor interaction potential accounts for the observed data. The experimental data are fitted by Larsen's theory of the hydrogenic problem. The excitonic mass obtaind from this fit is close to the reduced mass of the electron and the heavy hole. This seems to be a general result, confirmed byh reconsideration of older experimental data on free and bound excitons in GaSb, InSb, and Ge with the most recent band parameters.