MoRe Electrodes with 10-nm Nanogaps for Electrical Contact to Atomically Precise Graphene Nanoribbons

TL;DR

This paper demonstrates the fabrication of ultra-narrow nanogap electrodes using MoRe alloy to achieve low-resistance electrical contacts with atomically precise graphene nanoribbons, enabling their potential in electronic devices.

Contribution

It introduces a novel PMMA-assisted transfer technique and needle-like electrode fabrication for contacting single GNRs with 10 nm gaps using MoRe alloy.

Findings

Thermally-activated, gate-tunable conductance observed in GNR-MoRe transistors.

Successful fabrication of 10 nm nanogaps with needle-like electrodes.

Low-resistance contacts achieved with MoRe alloy.

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 nano-scale electrical contacts to the GNRs hinders harnessing their properties in field-effect transistors. In this paper, we make electrical contact with 9-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 towards contacting a single GNR by fabrication of electrodes with a needle-like geometry, with about 20 nm tip diameter and 10 nm separation. To preserve the nano-scale geometry of the contacts, we develop a PMMA-assisted technique to transfer the GNRs onto the pre-patterned electrodes. Our device characterizations as a function of bias-voltage and temperature, show a thermally-activated gate-tunable conductance in the GNR-MoRe-based transistors.