Quantum Confinement of Dirac Quasiparticles in Graphene Patterned with Sub-Nanometer Precision

Eva Cortés-del Río, Pierre Mallet, Héctor González-Herrero, José Luis Lado, Joaquín Fernández-Rossier, José María Gómez-Rodríguez, Jean-Yves Veuillen, Iván Brihuega

Research output: Contribution to journalArticleScientificpeer-review

Abstract

Quantum confinement of graphene Dirac-like electrons in artificially crafted nanometer structures is a long sought goal that would provide a strategy to selectively tune the electronic properties of graphene, including bandgap opening or quantization of energy levels. However, creating confining structures with nanometer precision in shape, size, and location remains an experimental challenge, both for top-down and bottom-up approaches. Moreover, Klein tunneling, offering an escape route to graphene electrons, limits the efficiency of electrostatic confinement. Here, a scanning tunneling microscope (STM) is used to create graphene nanopatterns, with sub-nanometer precision, by the collective manipulation of a large number of H atoms. Individual graphene nanostructures are built at selected locations, with predetermined orientations and shapes, and with dimensions going all the way from 2 nm up to 1 µm. The method permits the patterns to be erased and rebuilt at will, and it can be implemented on different graphene substrates. STM experiments demonstrate that such graphene nanostructures confine very efficiently graphene Dirac quasiparticles, both in 0D and 1D structures. In graphene quantum dots, perfectly defined energy bandgaps up to 0.8 eV are found that scale as the inverse of the dot’s linear dimension, as expected for massless Dirac fermions.

Original languageEnglish
Article number2001119
Number of pages7
JournalAdvanced Materials
Volume32
Issue number30
Early online date2020
DOIs
Publication statusPublished - Jul 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • atomic manipulation
  • graphene
  • graphene quantum dots
  • nanopatterning
  • scanning tunneling microscopy

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