Measurement of coherent tunneling between InGaAs quantum wells and InAs quantum dots using photoluminescence spectroscopy

We present a spectroscopic manifestation of the intermediate coherent tunneling regime between a quantum-dot (QD) and a quantum-well (QW) layer. We observe a nontrivial dependence of the resonant QD photoluminescence excitation (PLE) signal as a function of dot-well barrier thickness. For thick barriers and resonant QW excitation, the photogenerated QD carrier density increases exponentially with increasing coupling strength. For separations of a few nanometers only, however, we observe an anomalous decrease in the PLE signal. This behavior is defined by subpicosecond resonant coherent tunneling dynamics between the QW and QD. Our results shed light on the intermediate coherent tunneling regime of relevance in a variety of functional nanostructures such as charge or spin injectors or photovoltaic devices.