Dynamical transport of photoexcited carriers between shallow and deep quantum wells embedded in a GaAs/AlAs superlattice

Temperature dependence of the emission properties in a novel composite quantum-well-structure consisting of wide and narrow GaAs quantum wells (QWs) embedded in a GaAs/AlAs short-period superlattice (SPS) has been studied by steady-state and time-resolved photoluminescence (PL) measurements. At low temperature (~20 K), distinct PL peaks originating from the QWs and SPS are observed. When temperature is increased to 60 K, the PL intensity of the wide QW with deep confinement states significantly increases, while the ones of the narrow QW and the SPS gradually decrease. Above 100 K, however, the former PL intensity decreases and the latter ones increase. Temperature dependence of the measured PL decay behaviors directly evidences that the complex PL properties of the composite QWs are due to the interplay of the photoexcited carriers between the deep and shallow QWs by Bloch-type transport in the SPS.