Resonances in tunnelling between quantum wells

Time-resolved photoluminescence measurements in the picosecond regime on GaAs/Al0.35 Ga0.65As asymmetric double quantum well structures with perpendicular electric fields applied in both directions are reported. A large number of electron and hole resonances are detected. A splitting of the ground state resonances reveals the importance of excitonic effects. Longitudinal optical phonon assisted tunnelling plays a minor role for narrow quantum wells in comparison with impurity or interface roughness assisted transfer. Resonant electron tunnelling times depend exponentially on the square root of the effective barrier height and are an order of magnitude shorter than resonant hole tunnelling times.