Transport properties of quantum dots with steep walls

A. Fuhrer, S. Lüscher, T. Heinzel, K. Ensslin, W. Wegscheider, and M. Bichler
Phys. Rev. B 63, 125309 – Published 7 March 2001
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Abstract

Quantum dots are fabricated in a Ga[Al]As heterostructure by local oxidation with an atomic force microscope. This technique, in combination with top gate voltages, allows us to generate small lateral depletion lengths. The confinement is characterized by low-temperature magnetotransport measurements, from which the dots energy spectrum is reconstructed. We find that in small dots the addition spectrum can qualitatively be described within a Fock-Darwin model. For a quantitative analysis, however, a steep-wall confinement has to be considered. In large dots with small lateral depletion length, our measurements indicate that the density of states within Landau level 2 inside the dot is larger than that within Landau level 1, an effect that we interpret in terms of steep walls. Furthermore, we demonstrate that our interpretation is consistent within the charge-density model. The maximum wall steepness achieved is of the order of 0.4 meV/nm.

  • Received 11 September 2000

DOI:https://doi.org/10.1103/PhysRevB.63.125309

©2001 American Physical Society

Authors & Affiliations

A. Fuhrer, S. Lüscher, T. Heinzel, and K. Ensslin

  • Solid State Physics Laboratory, ETH Zürich, 8093 Zürich, Switzerland

W. Wegscheider

  • Walter Schottky Institut, TU München, 85748 Garching, Germany
  • Institut für Angewandte und Experimentelle Physik, Universität Regensburg, 93040 Regensburg, Germany

M. Bichler

  • Walter Schottky Institut, TU München, 85748 Garching, Germany

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Vol. 63, Iss. 12 — 15 March 2001

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