A wide band gap metal-semiconductor-metal nanostructure made entirely from graphene

TL;DR

This paper presents a scalable bottom-up method to produce atomically precise semiconducting graphene regions integrated within metallic graphene, using substrate interactions to control electronic properties without lithography.

Contribution

It introduces a novel approach to create atomically precise graphene junctions by exploiting substrate interactions, avoiding traditional lithographic limitations.

Findings

Produced a scalable, reproducible graphene junction with precise width control.

Demonstrated a semiconducting region with >0.5 eV energy gap within metallic graphene.

Showed minimal variation in electronic structure over tens of microns.

Abstract

A blueprint for producing scalable digital graphene electronics has remained elusive. Current methods to produce semiconducting-metallic graphene networks all suffer from either stringent lithographic demands that prevent reproducibility, process-induced disorder in the graphene, or scalability issues. Using angle resolved photoemission, we have discovered a unique one dimensional metallic-semiconducting-metallic junction made entirely from graphene, and produced without chemical functionalization or finite size patterning. The junction is produced by taking advantage of the inherent, atomically ordered, substrate-graphene interaction when it is grown on SiC, in this case when graphene is forced to grow over patterned SiC steps. This scalable bottomup approach allows us to produce a semiconducting graphene strip whose width is precisely defined within a few graphene lattice constants, a level of precision entirely outside modern lithographic limits. The architecture demonstrated in this work is so robust that variations in the average electronic band structure of thousands of these patterned ribbons have little variation over length scales tens of microns long. The semiconducting graphene has a topologically defined few nanometer wide region with an energy gap greater than 0.5 eV in an otherwise continuous metallic graphene sheet. This work demonstrates how the graphene-substrate interaction can be used as a powerful tool to scalably modify graphene's electronic structure and opens a new direction in graphene electronics research.