INTER-ISLAND ENERGY-TRANSFER IN ALGAAS GAAS QUANTUM-WELLS GROWN BY MOLECULAR-BEAM EPITAXY/

The results of photoluminescence, time-resolved photoluminescence, pho toluminescence excitation and photoluminescence kinetics studies are p resented for a Al0.3Ga0.7/GaAs quantum well system grown without growt h interruptions at the interfaces. The time-resolved photoluminescence measurements show drift of excitons towards lower energy states induc ed in a quantum well by potential fluctuations. We present also a firs t direct evidence for migration of free excitons from the 24 to 25 ML regions of the quantum well and interpret these results within a linea r rate model, deriving the transition rate of 290 ps(-1). Such inter-i sland migration processes have been observed till now only in growth i nterrupted structures.