Nanoribbons get metallic
Experts have succeeded in realising metallic graphene nanoribbons (GNRs) that are five carbon atoms wide.
Researchers at Finland’s Aalto University, part-funded by the European Research Council, demonstrated fabrication of the GNRs and measured their electronic structure. Experts have shown experimentally that certain atomically precise graphene nanoribbon widths are nearly metallic, in accordance with earlier predictions based on theoretical calculations. The results suggest that these extremely narrow and single-atom-thick ribbons could be used as metallic interconnects in future microprocessors.
Graphene nanoribbons have been proposed as ideal wires for use in future nanoelectronics: when the size of the wire is reduced to the atomic scale, graphene is expected to outperform copper in terms of conductance and resistance to electromigration, which is the typical breakdown mechanism in thin metallic wires. However, all demonstrated graphene nanoribbons have been semiconducting, which hampers their use as interconnects.
The team used an advanced scanning tunnelling microscopy that allows them to probe the material’s structure and properties with atomic resolution. Lead author of the study, Dr Amina Kimouche, said: “With this technique, we measured the properties of individual ribbons and showed that ribbons longer than five nanometres exhibit metallic behaviour.”
The nanoribbon fabrication is based on a chemical reaction on a surface. Dr Pekka Joensuu, who oversaw the synthesis of the precursor molecules for the ribbons, added: “The cool thing about the fabrication procedure is that the precursor molecule exactly determines the width of the ribbon. If you want one-carbon-atom-wide ribbons, you simply have to pick a different molecule.”
The full study is published in Nature Communications.
