RESONANCES IN TUNNELING BETWEEN QUANTUM-WELLS

Time-resolved photoluminescence measurements in the picosecond regime on GaAs/Al0.35Ga0.65As 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 splitt ing of the ground state resonances reveals the importance of excitonic effects. Longitudinal optical phonon assisted tunnelling plays a mino r role for narrow quantum wells in comparison with impurity or interfa ce roughness assisted transfer. Resonant electron tunnelling times dep end exponentially on the square root of the effective barrier height a nd are an order of magnitude shorter than resonant hole tunnelling tim es.