Identification of donors in GaAs by resonantly excited high-field magnetospectroscopy

The use of magnetospectroscopy of donor-bound excitons in the low-temperature (1.7 K) photoluminescence spectrum of GaAs for the identification of shallow donor species in low-doped epitaxial GaAs is described. The selective excitation of individual donor species in excited final-state (2p-, 2p0) transitions by tuning a dye laser into resonance with a corresponding component of the principal neutral donor-bound exciton lines is discussed. Individual components of the principal neutral donor-bound exciton peaks corresponding to different donor species are directly resolved in luminescence for the first time. Individual donors are also resolved in the ionized donor-bound excitation peaks, and Haynes' rule relationships are determined for both neutral and ionized donor-bound excitons. Shallow acceptors are identified in high-fields from the principal neutral acceptor-bound exciton peaks; the central-cell corrections to the exciton localization energies are found to be increased by the field.