Graphene Quantum Dots Probed by Scanning Tunneling Microscopy

Markus Morgenstern, Nils Freitag, Alexander Nent, Peter Nemes-Incze, Marcus Liebmann

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4 Citations (Scopus)

Abstract

Scanning tunneling spectroscopy results probing the electronic properties of graphene quantum dots are reviewed. After a short summary of the study of squared wave functions of graphene quantum dots on metal substrates, we firstly present data where the Landau level gaps caused by a perpendicular magnetic field are used to electrostatically confine electrons in monolayer graphene, which are probed by the Coulomb staircase revealing the consecutive charging of a quantum dot. It turns out that these quantum dots exhibit much more regular charging sequences than lithographically confined ones. Namely, the consistent grouping of charging peaks into quadruplets, both, in the electron and hole branch, portrays a regular orbital splitting of about 10meV. At low hole occupation numbers, the charging peaks are, partly, additionally grouped into doublets. The spatially varying energy separation of the doublets indicates a modulation of the valley splitting by the underlying BN substrate. We outline that this property might be used to eventually tune the valley splitting coherently. Afterwards, we describe graphene quantum dots with multiple contacts produced without lithographic resist, namely by local anodic oxidation. Such quantum dots target the goal to probe magnetotransport properties during the imaging of the corresponding wave functions by scanning tunneling spectroscopy.

Original languageEnglish
Article number1700018
JournalAnnalen der Physik
Volume529
Issue number11
DOIs
Publication statusPublished - Nov 2017

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Keywords

  • Graphene quantum dots
  • local anodic oxidation
  • scanning tunneling microscopy
  • valley splitting

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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