Interface Coupling as a Crucial Factor for Spatial Localization of Electronic States in a Heterojunction of Graphene Nanoribbons

Abstract

The heterojunction (HJ) band structures of graphene nanoribbons (GNRs), generated by modulating ribbon width, are currently considered for use in tunnel field-effect transistors and optoelectronic applications, but interfacial states often exist and remove the band offsets. Here first-principles calculations show that these states are induced by C---C bonds at the interfacial edge, and can be eliminated by ``spare'' coupling of wide and narrow GNR segments, which is predicted to be stable at room temperature. Knowing how best to construct GNR HJs naturally will promote the technologies based on them.