Creating and probing wide-bandgap nanoribbon-like structures in a continuous metallic graphene sheet

TL;DR

This paper demonstrates a novel method to create wide bandgap nanoribbon-like structures in continuous graphene sheets through strain engineering and substrate interaction, enabling metallic-semiconducting-metallic junctions without cutting the graphene.

Contribution

It introduces a new approach to induce bandgaps in graphene by strain and substrate effects, avoiding the need for physical cutting into nanoribbons.

Findings

Bandgap of hundreds of meV observed in GNR-like structures

Continuous graphene can host metallic-semiconducting-metallic junctions

Strain engineering enables tailoring of electronic properties

Abstract

The light-like dispersion of graphene monolayer results in many novel electronic properties in it1, however, this gapless feature also limits the applications of graphene monolayer in digital electronics2. A rare working solution to generate a moderate bandgap in graphene monolayer is to cut it into one-dimensional (1D) nanometre-wide ribbons3-13. Here we show that a wide bandgap can be created in a unique 1D strained structure, i.e., graphene-nanoribbon-like (GNR-like) structure, of a continuous graphene sheet via strong interaction between graphene and the metal substrate, instead of cutting graphene monolayer. The GNR-like structures with width of only a few nanometers are observed in a continuous graphene sheet grown on Rh foil by using thermal strain engineering. Spatially-resolved scanning tunnelling spectroscopy revealed bandgap opening of a few hundreds meV in the GNR-like structure in an otherwise continuous metallic graphene sheet, directly demonstrating the realization of a metallic-semiconducting-metallic junction entirely in a graphene monolayer. We also show that it is possible to tailor the structure and electronic properties of the GNR-like structure by using scanning tunnelling microscope.