Photoluminescence study of photoexcited electrons in asymmetric double quantum wells

Time-resolved and continuous wave photoluminescence measurements in asymmetric double quantum wells with coupled narrow and wide quantum wells of GaAs/AlGaAs heterostructures are carried out to investigate the electron tunneling mechanism between the two quantum wells. By applying external voltage perpendicular to the interfaces, the subband spacing between the wide and the narrow quantum well states can be changed resulting in a change in the effective tunneling process. The decay time for electrons in the upper subband is found to be minimum at a certain applied voltage. This reduction in the decay time is attributed to resonant optical-phonon scattering.