Magneto-optical determination of exciton binding energies in quantum-wire superlattices

Polarization-resolved photoluminescence excitation spectra of (Al, Ga)As serpentine superlattice quantum-wire arrays have been measured in magnetic fields up to 20 T. In the Faraday configuration we are able to resolve Landau-level-like magnetoexciton transitions in the low-field limit, and to directly determine the exciton binding energy. A maximum enhancement of excitonic binding by 70% is observed in a 160-{}-wide quantum wire array as compared to a two-dimensional reference, and the true superlattice character is evidenced by a decreased excitonic binding for a short period (54 {} wide) compared to a long period quantum-wire array (160 {} wide). {} 1996 The American Physical Society.