MoRe Electrodes with 10 nm Nanogaps for Electrical Contact to Atomically Precise Graphene Nanoribbons
Damian Bouwmeester (Kavli institute of nanoscience Delft, TU Delft - QN/van der Zant Lab)
Talieh S. Ghiasi (Kavli institute of nanoscience Delft, TU Delft - QN/van der Zant Lab)
Gabriela Borin Barin (Swiss Federal Laboratories for Materials Science and Technology (Empa))
Klaus Müllen (Max Planck Institute for Polymer Research)
Pascal Ruffieux (Swiss Federal Laboratories for Materials Science and Technology (Empa))
Roman Fasel (Swiss Federal Laboratories for Materials Science and Technology (Empa), University of Bern)
Herre S.J. van der Zant (TU Delft - QN/van der Zant Lab, Kavli institute of nanoscience Delft)
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Abstract
Atomically precise graphene nanoribbons (GNRs) are predicted to exhibit exceptional edge-related properties, such as localized edge states, spin polarization, and half-metallicity. However, the absence of low-resistance nanoscale electrical contacts to the GNRs hinders harnessing their properties in field-effect transistors. In this paper, we make electrical contact with nine-atom-wide armchair GNRs using superconducting alloy MoRe as well as Pd (as a reference), which are two of the metals providing low-resistance contacts to carbon nanotubes. We take a step toward contacting a single GNR by fabricating electrodes with needlelike geometry, with about 20 nm tip diameter and 10 nm separation. To preserve the nanoscale geometry of the contacts, we develop a PMMA-assisted technique to transfer the GNRs onto the prepatterned electrodes. Our device characterizations as a function of bias voltage and temperature show thermally activated gate-tunable conductance in GNR-MoRe-based transistors.
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