ENHANCEMENT OF NONRADIATIVE INTERFACE RECOMBINATION IN GAAS COUPLED QUANTUM WELLS

The recombination dynamics of GaAs multiple quantum wells as a function of barrier widths LB are studied in a semiconductor in the range between LB=0.87 nm (superlattice) and LB=18.1 nm (uncoupled wells) by means of cathodo- and photoluminescence. With decreasing LB the nonradiative recombination rate is found to be drastically enhanced, where-as the radiative recombination probability decreases. Thus a pronounced decrease of the quantum efficiency results. The controlled variation of the barrier width is found to be decisive for an unambiguous identification of the origin of the traps which are responsible for the nonradiative processes: Comparison with a theoretical calculation shows that they are localized at the heterointerfaces and not in the barriers.