Programme

O.3 -- Oral, NCTP-43

Date: Monday, 30 July 2018

Time: 11:10 - 11:30

Influence of the electric field on the optical properties of bilayer graphene nanoribbons

Thai Thanh Lap (1), Dao Thuy Tuong Vi (1), Vu Thanh Tra (2)

(1) College of Natural Sciences, Can Tho University, Can Tho, Vietnam; (2) School of Education, Can Tho University, Can Tho, Vietnam.

Recently, increasing attention has been paid to multilayer graphene, especially to bilayer graphene which consists of two coupled graphene sheets [1]. Interlayer interactions in bilayer graphene destroy symmetry and isotropy of energy bands and change linear bands (in monolayer graphene) into parabolic bands with the slight overlap between the highest occupied valence band and the lowest unoccupied conduction band. Recent experimental and theoretical studies show that the bandgap of bilayer graphene is widely tunable by external electric fields [2,3]. In this work, the optical properties of bilayer graphene nanoribbons under effects of external electric fields are investigated by using tight-binding model and the gradient approximation. The electric field can induce to the subband (anti)crossing, change the subband spacing, cause the oscillating bands, and increase the band-edge states as well. Our results demonstrate that the optical absorption spectra exhibit rich prominent peaks structure mainly due to the subbands. In addition, the number, spectral intensity, and energy of the absorption peaks are strongly dependent on the interlayer atomic interactions and the ribbon width. The dependence of the optical excitations on both the magnitude and direction of the electric field is studied as well. These theoretical predictions could be validated by optical spectroscopy measurements. These results provide the possibilities for applying future optoelectronic applications base on bilayer graphene nanoribbons. [1] Woo Jong Yu et al., Sci. Rep. 3, 1248 (2013). [2] Yuanbo Zhang et al., Nature 459 820–823 (2009). [3] Thanh-Tra Vu et al., Superlattice. Microstruct. 102 451-458 (2017).

Presenter: Thai Thanh Lap