Electronic Band-Engineering of a Dumbbell-shaped Graphene Nanoribbon by the Application of Uniaxial Tensile Strain

Graphene nanoribbons (GNRs) narrower than 70 nm are theoretically known to exhibit semiconductive properties, and thus, they were applied to photovoltaic devices with multi-band gap. A dumbbell-shape GNR (DSGNR) structure which consisted of a narrow semiconductive GNR and wide metallic GNRs at both ends was found to show no Schottky barrier around the interface between those GNRs and its effective bandgap varied under the application of uniaxial tensile strain. The photovoltaic properties of the DSGNR structures were validated by the area-arrayed 40-nm wide DSGNR structure on a silicon substrate and the large piezoresistive effect, in other words, large change of bandgap was also validated by the DSGNR transferred on a soft PDMS substrate.