In-situ electronic characterization of graphene nanoconstrictions fabricated in a transmission electron microscope

TL;DR

This study demonstrates in-situ electronic measurements of graphene nanoconstrictions fabricated in a TEM, revealing high conductance and current densities down to 1 nm width, advancing nanoscale graphene device understanding.

Contribution

First in-situ measurement of GNC conductance with precise width control down to 1 nm, showing high conductance and exceptional current densities.

Findings

GNC conductance scales with width approximately as a power law.

GNCs support current densities >120 μA/nm², much higher than previous reports.

Conductance comparable to exfoliated graphene of similar size.

Abstract

We report electronic measurements on high-quality graphene nanoconstrictions (GNCs) fabricated in a transmission electron microscope (TEM), and the first measurements on GNC conductance with an accurate measurement of constriction width down to 1 nm. To create the GNCs, freely-suspended graphene ribbons were fabricated using few-layer graphene grown by chemical vapor deposition. The ribbons were loaded into the TEM, and a current-annealing procedure was used to clean the material and improve its electronic characteristics. The TEM beam was then used to sculpt GNCs to a series of desired widths in the range 1 - 700 nm; after each sculpting step, the sample was imaged by TEM and its electronic properties measured in-situ. GNC conductance was found to be remarkably high, comparable to that of exfoliated graphene samples of similar size. The GNC conductance varied with width approximately as, where w is the constriction width in nanometers. GNCs support current densities greater than 120 \muA/nm2, two orders of magnitude higher than has been previously reported for graphene nanoribbons and 2000 times higher than copper.