Formation of quantum dots in the potential fluctuations of InGaAs heterostructures probed by scanning gate microscopy

P. Liu, F. Martins, B. Hackens, L. Desplanque, X. Wallart, M. G. Pala, S. Huant, V. Bayot, and H. Sellier
Phys. Rev. B 91, 075313 – Published 25 February 2015

Abstract

The disordered potential landscape in an InGaAs/InAlAs two-dimensional electron gas patterned into narrow wires is investigated by means of scanning gate microscopy. It is found that scanning a negatively charged tip above particular sites of the wires produces conductance oscillations that are periodic in the tip voltage. These oscillations take the shape of concentric circles whose number and diameter increase for more negative tip voltages until full depletion occurs in the probed region. These observations cannot be explained by charging events in material traps, but are consistent with Coulomb blockade in quantum dots forming when the potential fluctuations are raised locally at the Fermi level by the gating action of the tip. This interpretation is supported by simple electrostatic simulations in the case of a disorder potential induced by ionized dopants. This work represents a local investigation of the mechanisms responsible for the disorder-induced metal-to-insulator transition observed in macroscopic two-dimensional electron systems at low enough density.

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  • Received 24 April 2014
  • Revised 9 October 2014

DOI:https://doi.org/10.1103/PhysRevB.91.075313

©2015 American Physical Society

Authors & Affiliations

P. Liu1,2,*, F. Martins3, B. Hackens3, L. Desplanque4, X. Wallart4, M. G. Pala5, S. Huant1,2, V. Bayot1,2,3, and H. Sellier1,2,†

  • 1Université Grenoble Alpes, Institut NEEL, F-38000 Grenoble, France
  • 2CNRS, Institut NEEL, F-38042 Grenoble, France
  • 3IMCN/NAPS, Université catholique de Louvain, B-1348 Louvain-la-Neuve, Belgium
  • 4IEMN, UMR CNRS 8520, UST Lille, F-59652 Villeneuve d'Ascq, France
  • 5IMEP-LAHC, Grenoble INP, Minatec, F-38016 Grenoble

  • *Present address: School of Innovation & Entrepreneurship, Peking University, Beijing, China.
  • hermann.sellier@neel.cnrs.fr

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Vol. 91, Iss. 7 — 15 February 2015

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