Abstract
We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface. Within the tight-binding model, the optical absorption is calculated for quantum dots, of triangular and hexagonal shapes, with zigzag and armchair edge terminations. We show that in triangular silicene clusters with zigzag edges a rich and widely tunable infrared absorption peak structure originates from transitions involving zero energy states. The edge of absorption in silicene quantum dots undergoes red shift in the external electric field for triangular clusters, whereas blue shift takes place for hexagonal ones. In small clusters of bilayer graphene with zigzag edges the edge of absorption undergoes blue/red shift for triangular/hexagonal geometry. In armchair clusters of silicene blue shift of the absorption edge takes place for both cluster shapes, while red shift is inherent for both shapes of the bilayer graphene quantum dots.
Highlights
Non-planar graphene-derivative materials have attracted considerable attention1–8 because of their tunable electronic properties, different from those of the single-layer graphene
We study numerically the optical properties of low-buckled silicene and AB-stacked bilayer graphene quantum dots subjected to an external electric field, which is normal to their surface
We discuss the effect of an electric field on the optical absorption cross section in silicene and bilayer graphene quantum dots (QDs) and how the applied field can control the number and intensities of absorption peaks
Summary
Non-planar graphene-derivative materials have attracted considerable attention because of their tunable electronic properties, different from those of the single-layer graphene. Application of the electric field, E, across the bilayer (multilayer) graphene system opens a gap between the conduction and valence bands.. The atoms of the type A and B of the lattice are displaced alternatively in the vertical direction and are subjected to a different, electric field producing, potential gradient. The possibility of controlling the gap offers a wealth of new routes for the generation of field effect transistors and optoelectronic devices.. We discuss the effect of an electric field on the optical absorption cross section in silicene and bilayer graphene QDs and how the applied field can control the number and intensities of absorption peaks.
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