Excited state coherent resonant electronic tunneling in quantum well-quantum dot hybrid structures

A strong effect of a quantum well (QW) incorporated into a quantum dot (QD) structure on the density of states of the system and the efficiency of carrier transfer from the barrier material to QDs is revealed in InAs/GaAs-InGaAs/GaAs dot-well, tunnel-injection structures. When tuning the QW states in resonance with excited QD states, the carrier flux can be effectively controlled by varying the spacer thickness or barrier height. Enhanced carrier tunneling between QW and QD states is observed by means of photoluminescence excitation spectroscopy for reduced spacer thicknesses. Our results demonstrate that resonant coherent electron tunneling is substantially faster for the second than for the first QW subband and results in the formation of hybrid electronic states delocalized across the QW/QD interface. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3560063]