Electric-field induced modification of electronic properties of few-layer graphene nanoribbons

In the presence of electric fields, the low-energy electronic properties of AB -stacked few-layer graphene nanoribbons are studied by using the tight-binding model. They are strongly dependent on the geometric structures (the interlayer interactions, the ribbon edges, the ribbon width Ny, and the ribbon number Nz) and the field strength. The interlayer interactions significantly affect density of states (DOS), energy gap (Eg), band structure, and free carriers. DOS exhibits many special structures including plateau, discontinuities, and divergent peaks. The effective electric field modifies the energy dispersions, alters the subband spacing, changes the subband curvature, produces the new edge state, switches the band gap, and causes the metal-semiconductor (or semiconductor-metal) transitions. In gapless zigzag ribbons, electric fields not only lifts the degeneracy of partial flatbands at EF but also induces an energy gap. Eg is dependent on the ribbon width, ribbon edges, and the field strength. The semiconductor-metal transitions occur in both armchair ribbons and zigzag ribbons in the increase in electric fields. Due to electric fields, the above-mentioned effects are completely reflected in the features of DOS, such as the generation of special structures, the shift of peak position, the change in peak height, and the alternation of band gap. The predicted electronic properties could be examined by the experimental measurements on absorption spectra and transport properties.