Tunable Bandgap in Bilayer Armchair Graphene Nanoribbons: Concurrent Influence of Electric Field and Uniaxial Strain

In this paper, the effect of uniaxial strain on the electronic properties of bilayer armchair graphene nanoribbons (BLAGNRs) is theoretically investigated for the first time. Our calculations based on density functional theory (DFT) reveal the tunable nature of the electronic properties of BLAGNRs with the application of uniaxial strain. We further explore the simultaneous effect of perpendicular electric field and uniaxial strain on the electronic bandgap. The results show that as long as the strain induced bandgap is smaller than a critical value of 0.2 eV, the electric field can significantly modulate the bandgap. In addition, we modified nearest neighbor tight-binding (TB) parameters to include the effect of the hydrogen passivation, which results in an excellent agreement between the electronic bandstructures obtained from DFT and TB calculations. Finally, by employing the nonequilibrium Green´s function formalism, an on-off conductance ratio as high as 10⁵ is predicted for strained BLAGNRs.