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Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 7: Quantum dots and wires: Optical properties I

HL 7.2: Talk

Monday, March 27, 2006, 10:30–10:45, POT 151

Impact of Piezoelectricity on Shape and Order of Wavefunctions in Uncapped InAs/GaAs Quantum Dots — •Andrei Schliwa1, Theophilos Maltezopoulos2, Markus Morgenstern3, Roland Wiesendanger2, and Dieter Bimberg11Institut für Festkörperphysik, Technische Universität*Berlin — 2Institute of Applied Physics, University of Hamburg — 3II. Inst. of Physics B, RWTH Aachen University

Recently it became possible to map the shape of electron wave-functions in uncapped InAs/GaAs quantum dots (QDs) by using scanning tunneling spectroscopy (STS) [1]. These measurement revealed an anomalous order of the single particle states in most of the investigated QDs which triggered the here presented theoretical investigations based on the eight-band-k·p model.
The outer shape of the model-QD is specified by using the morphological data, recorded as a byproduct of the STS-method, whilst the composition profile has been treated as variable. All of the measured QDs are elongated in [110] direction with a larger in-plane anisotropy-ratio at the QD-apex than at the bottom. This alone however is not sufficient to explain the observed wavefunction order. It requires the inclusion of the strain induced piezoelectric field to amplify the already present confinement anisotropy to finally obtain the anomalous order of the electron orbitals in the simulation.
[1] Maltezopoulos T., Bolz A., Meyer C., Heyn C., Hansen W., Morgenstern M., Wiesendanger R., Phys. Rev. Lett. 91, p.196804 (2003)

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