Exciton localization dynamics due to shallow and deep isoelectric traps in a triple GaAs quantum well grown by growth-interrupted molecular beam epitaxy

We have investigated the exciton localization dynamics in a triple GaAs quantum well (QW) system which consists of different well thicknesses separated by thick Al_0.17Ga_0.83As barriers, prepared by growth-interrupted molecular beam epitaxy. Due to the formation of atomically-flat QW growth islands, sharply split exciton emission lines corresponding to the monolayer terraces are clearly observed in low temperature photoluminescence (PL) spectra, and they exhibit a variety of interesting recombination dynamics which reflect exciton transfer between the different terraces (shallow traps) as well as between the different QW´s (deep traps). Based on steady-state and time-resolved PL measurements, experimental evidence is given to show that the three electronically isolated QW´s are interacting and competing to capture photoexcited carriers, and their dynamics strongly varies as a function of lattice temperature