A wide-bandgap metal–semiconductor–metal nanostructure made entirely from graphene

Abstract

Present methods for producing semiconducting–metallic graphene networks suffer from stringent lithographic demands, process-induced disorder in the graphene, and scalability issues. Here we demonstrate a one-dimensional metallic–semiconducting–metallic junction made entirely from graphene. Our technique takes advantage of the inherent, atomically ordered, substrate–graphene interaction when graphene is grown on SiC, in this case patterned SiC steps, and does not rely on chemical functionalization or finite-size patterning. This scalable bottom-up approach allows us to produce a semiconducting graphene strip whose width is precisely defined to within a few graphene lattice constants, a level of precision beyond modern lithographic limits, and which is robust enough that there is little variation in the electronic band structure across thousands of ribbons. The semiconducting graphene has a topographically defined few-nanometre-wide region with an energy gap greater than 0.5 eV in an otherwise continuous metallic graphene sheet. The electronic properties of graphene are spatially controlled from metallic to semiconducting by patterning steps into the underlying silicon carbide substrate. This bottom-up approach could be the basis for integrated graphene electronics.