Anomalously large stokes and anti-stokes real space charge transfer between quantum wells separated by thickn alloy barriers: beyond the mean field approach

摘要

Anomalously large rela space charge transfer through thick alloy barriers in GaAs asymmetric doble quantum wells is studied by photoluminescence excitation. This inter-well excitonic transfer is very large when the barrier is the Al_(0.3)Ga_(0.7)As alloy, but disappears when the barrier is GaAs/GaAs digital alloy with an equivalent x chemical bounds 0.28. Furthermore, for a shallow INGaAs/GaAs/InGaAs ADQW, it laetgely disappears desiptie the lower barrier hight. These results suggest that the inhomogenities of the atomic arrangment of Ga and Al in the alloy, which is a strong function of x, might be responsible for this transfer. This picture is qualitatively supported by quantum mechanical caculation in three dimenions whose scopes reach beyond the mean field approach. We, furthermore, presents the existence of an anti-Stokes transfer from the wide well to the narrow well, and discuss its origin.