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

摘要

We report electronic measurements on high-quality graphene nanoconstrictions(GNCs) fabricated in a transmission electron microscope (TEM), and the firstmeasurements on GNC conductance with an accurate measurement of constrictionwidth down to 1 nm. To create the GNCs, freely-suspended graphene ribbons werefabricated using few-layer graphene grown by chemical vapor deposition. Theribbons were loaded into the TEM, and a current-annealing procedure was used toclean the material and improve its electronic characteristics. The TEM beam wasthen 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 electronicproperties measured in-situ. GNC conductance was found to be remarkably high,comparable to that of exfoliated graphene samples of similar size. The GNCconductance varied with width approximately as, where w is the constrictionwidth in nanometers. GNCs support current densities greater than 120 \muA/nm2,two orders of magnitude higher than has been previously reported for graphenenanoribbons and 2000 times higher than copper.