Armchair graphene nanoribbons: Electronic structure and electric-field modulation

We report electronic structure and electric-field modulation calculations in the width direction for armchair graphene nanoribbons (acGNRs) using a semiempirical extended Huckel theory. Important band-structure parameters are computed, e.g., effectives masses, velocities, and band gaps. For the three types of acGNRs, the p(z) orbital tight-binding parameters are extracted if feasible. Furthermore, the effect of electric field in the width direction on acGNRs dispersion is explored. It is shown that for the two types of semiconducting acGNRs, an external electric field can reduce the band gap to a few meV with different quantitative behaviors.