INTERWELL ENHANCEMENT OF THE PHOTOLUMINESCENCE EFFICIENCY IN GAAS/ALGAAS QUANTUM-WELLS

We have investigated the effects of carriers generated in quantum wells adjacent to a single 100-angstrom-thick GaAs quantum well. The AlGaAs barrier thicknesses were such (200 angstrom) that the different quantum wells were not electronically coupled. At certain excitation power densities we observe an increase in luminescence in the excitation spectrum of the 100 angstrom quantum well corresponding to transitions in the quantum wells of different thicknesses. We attribute these interwell effects to the partial saturation of mutual nonradiative centers in the barrier material. At high excitation power densities we observe previously unreported negative interwell transitions which we attribute to an internally generated electric field.