Work

Stacking and edge dependent bandgap modulation in AA- and AB- stacked bilayer graphene nanoribbons induced by gate voltage

Year: 2025

Type: article

Abstract: This paper investigates the effect of gate voltage on bandgap modulation in bilayer graphene nanoribbons (BGNRs) with AA and AB stacking configurations, considering both zigzag and armchair edge geometries. Using a direct k -space diagonalisation approach applied to the nearest-neighbour tight-binding (NNTB) Hamiltonian, the study systematically examines electronic properties across a broad parameter space defined by stacking order, edge type, ribbon width classified by unit cells and gate voltages up to 2 eV. The applied gate voltage generates an electric field that breaks inversion symmetry, enabling controlled bandgap tuning. Results reveal distinct stacking- and edge-dependent properties: zigzag AA-BGNRs show minimal bandgap variation, whereas zigzag AB-BGNRs exhibit significant, nearly linear bandgap modulation under gate voltage. For armchair BGNRs, the electronic response varies with ribbon width families (3 n , 3 n + 1, 3 n + 2) and stacking type. Notably, the 3 n and 3 n + 2 families remain semiconducting at zero bias, with the 3 n family presenting the largest intrinsic bandgaps (~ 0.6 eV for AA, ~ 1.3 eV for AB) and distinct gate-induced modulation. The 3 n + 1 family, metallic in AA stacking regardless of gate voltage, undergoes a metal-to-semiconductor transition in AB stacking, with the bandgap opening and increasing as gate voltage rises. This comprehensive analysis provides quantitative insights into intrinsic and tunable bandgaps, establishing a unified framework for understanding stacking- and width-dependent electronic properties in BGNRs. The findings offer valuable design guidelines for gate-tunable nanoelectronic and optoelectronic devices, including field-effect transistors and reconfigurable circuits, by linking electronic properties directly to ribbon structural parameters.

Source: Applied Physics A

DOI: 10.1007/s00339-025-08813-3