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arXiv · 1611.07405

Modulation of bandgap in bilayer armchair graphene ribbons by tuning vertical and transverse electric fields

Thanh-Tra Vu·Thi-Kim-Quyen Nguyen·Anh-Huy Huynh·Thi-Kim-Loan Phan·Van-Truong Tran
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Abstract

We investigate the effects of external electric fields on the electronic properties of bilayer armchair graphene nano-ribbons. Using atomistic simulations with Tight Binding calculations and the Non-equilibrium Green function formalism, we demonstrate that (i) in semi-metallic structures, vertical fields impact more effectively than transverse fields in terms of opening larger bandgap, showing a contrary phenomenon compared to that demonstrated in previous studies in bilayer zigzag graphene nano-ribbons; (ii) in some semiconducting structures, if transverse fields just show usual effects as in single layer armchair graphene nano-ribbons where the bandgap is suppressed when varying the applied potential, vertical fields exhibit an anomalous phenomenon that the bandgap can be enlarged, i.e., for a structure of width of 16 dimer lines, the bandgap increases from 0.255 eV to the maximum value of 0.40 eV when a vertical bias equates 0.96 V applied. Although the combined effect of two fields does not enlarge the bandgap as found in bilayer zigzag graphene nano-ribbons, it shows that the mutual effect can be useful to reduce faster the bandgap in semiconducting bilayer armchair graphene nano-ribbons. These results are important to fully understand the effects of electric fields on bilayer graphene nano-ribbons (AB stacking) and also suggest appropriate uses of electric gates with different edge orientations.

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Thanh-Tra Vu, Thi-Kim-Quyen Nguyen, Anh-Huy Huynh, Thi-Kim-Loan Phan, Van-Truong Tran. 2016-11-22. Modulation of bandgap in bilayer armchair graphene ribbons by tuning vertical and transverse electric fields. https://doi.org/10.1016/j.spmi.2016.12.031

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