Carnegie Mellon University
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Electronic States of InAs/GaAs Quantum Dots by Scanning Tunneling Spectroscopy

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journal contribution
posted on 2010-01-01, 00:00 authored by S. Gaan, Guowei He, Randall FeenstraRandall Feenstra, J. Walker, Elias ToweElias Towe

InAs/GaAs quantum-dot heterostructures grown by molecular-beam epitaxy are studied using cross-sectional scanning tunneling microscopy and spectroscopy. Individual InAs quantum dots (QDs) are resolved in the images. Tunneling spectra acquired 3-4 nm from the QDs show a peak located in the upper part of the GaAs bandgap originating from the lowest electron confined state, together with a tail extending out from the valence band from hole confined states. A line-shape analysis is used to deduce the binding energies of the electron and hole QD states.