Electronic transport in helium-ion-beam etched encapsulated graphene nanoribbons
G. Nanda (Kavli institute of nanoscience Delft, TU Delft - QN/Kavli Nanolab Delft)
Gregor Hlawacek (Institut für Ionenstrahlphysik und Materialforschung)
S. Goswami (TU Delft - QuTech Advanced Research Centre, TU Delft - QRD/Kouwenhoven Lab, Kavli institute of nanoscience Delft, TU Delft - QN/Quantum Transport, TU Delft - QRD/Goswami Lab)
Kenji Watanabe (National Institute for Materials Science)
Takashi Taniguchi (National Institute for Materials Science)
P.F.A. Alkemade (TU Delft - QN/Kavli Nanolab Delft, Kavli institute of nanoscience Delft)
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Abstract
We report the etching of and electronic transport in nanoribbons of graphene sandwiched between atomically flat hexagonal boron nitride (h-BN). The etching of ribbons of varying width was achieved with a focused beam of 30 keV He+ ions. Using in-situ electrical measurements, we established a critical dose of 7000 ions nm−2 for creating a 10 nm wide insulating barrier between a nanoribbon and the rest of the encapsulated graphene. Subsequently, we measured the transport properties of the ion-beam etched graphene nanoribbons. Conductance measurements at 4 K show an energy gap, that increases with decreasing ribbon width. The narrowest ribbons show a weak dependence of the conductance on the Fermi energy. Furthermore, we observed power-law scaling in the measured current-voltage (I-V) curves, indicating that the conductance in the helium-ion-beam etched encapsulated graphene nanoribbons is governed by Coulomb blockade.
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