The Effect of Critical Electric Fields on the Electronic Distribution of Bilayer Armchair Graphene Nanoribbons

Abstract

We employed tight-binding calculations and Green’s function formalism to investigate the effect of applied electric fields on the energy band and electronic properties of bilayer armchair graphene nanoribbons (BL-AGNRs). The results show that the perpendicular electric field has a strong impact on modifying and controlling the bandgap of BL-AGNRs. At the critical values of this electric field, distortions of energy dispersion in subbands and the formation of new electronic excitation channels occur strongly. These originate from low-lying energies near the Fermi level and move away from the zero-point with the increment of the electric field. Phase transitions and structural changes clearly happen in these materials. The influence of the parallel electric field is less important in changing the gap size, resulting in the absence of the critical voltage over a very wide range [–1.5 V; 1.5 V] for the semiconductor-insulator group. Nevertheless, it is interesting to note the powerful role of the parallel electric field in modifying the energy band and electronic distribution at each energy level. These results contribute to an overall picture of the physics model and electronic structure of BL-AGNRs under stimuli, which can be a pathway to real applications in the future, particularly for electronic devices.

Correlation between energy band transition and optical absorption spectrum in bilayer armchair graphene nanoribbons

“…In detail, the tendency of inducing and modulating the energy gap in group 3p + 2 of the armchair ribbons and the zigzag ones is similar under the impact of both transverse and perpendicular electric fields [27][28][29]. On the contrary, the semiconducting-to-metal transition is observed for two groups 3p and 3p + 1 of armchair ribbons under the effect of these electric fields [30]. That is to say, for BL-GNRs, the optical spectra for different families of armchair edges could exhibit diverse transformations under the impact of stimuli and need to be investigated.…”

“…It has been demonstrated that external electric fields can modulate the electronic properties of BL-AGNRs that changes can be visibly observed in the band structure and the DOS of this material [27][28][29][30]. This means that both the gap size and the electron distribution are modulated significantly with electrostatic potentials.…”