Electronic and optical properties of graphene nanoribbons in external fields

Abstract

A review work is done for the electronic and optical properties of graphene nanoribbons in magnetic, electric, composite, and modulated fields. Effects due to the lateral confinement, curvature, stacking, non-uniform subsystems and hybrid structures are taken into account. The special electronic properties, induced by complex competitions between external fields and geometric structures, include many one-dimensional parabolic subbands, standing waves, peculiar edge-localized states, width- and field-dependent energy gaps, magnetic-quantized quasi-Landau levels, curvature-induced oscillating Landau subbands, crossings and anti-crossings of quasi-Landau levels, coexistence and combination of energy spectra in layered structures, and various peak structures in the density of states. There exist diverse absorption spectra and different selection rules, covering edge-dependent selection rules, magneto-optical selection rule, splitting of the Landau absorption peaks, intragroup and intergroup Landau transitions, as well as coexistence of monolayer-like and bilayer-like Landau absorption spectra. Detailed comparisons are made between the theoretical calculations and experimental measurements. The predicted results, the parabolic subbands, edge-localized states, gap opening and modulation, and spatial distribution of Landau subbands, have been identified by various experimental measurements.

Optoelectronic Properties of Van Der Waals Hybrid Structures: Fullerenes on Graphene Nanoribbons

“…The common feature observed in the optical spectra of both structures is the characteristic redshift of the absorption edge induced by the electric field. This is an expected result because the structure of the infrared absorption mainly originates from transitions between states of the 10GR [13,17]. For photon energies higher than 1.5 eV, it is possible to differentiate two types of resonances in terms of its dependence with the electric field intensity.…”

“…It is well known that graphene nanoribbons hold unique geometrical-dependent electronical properties that can be tuned by varying the width of the nanoribbon and the structure of its edges [13]. Our calculations show that complexes formed by fullerenes adsorbed on armchair graphene nanoribbons (GR) display very interesting electronic and optical properties due to the interplay effects between the ribbon finite widths and the fullerene size.…”

Electro-optical properties of phosphorene quantum dots

“…Within the single orbital model the dimension of the matrix Hamiltonian is naturally equal to the number of atoms in the structure. The p z -orbital tight-binding model has been widely used for the investigation of graphene structures [55] including monolayer [35,37] and bilayer [32,33] graphene QDs. A similar model has been deployed for group IV 2D materi-als [56] and GaAs monolayers [57].…”

Alkali-created rich properties in grapheme nanoribbons: Chemical bondings

“…GNRs exhibit the feature-rich essential properties, such as, electronic structures 5, 32 , magnetic properties 32, 33 , optical spectra 34, 35 , and transport properties 36, 37 . The electronic properties are diversified by changing by the ribbon width (W) 38, 39 , edge structure 38, 40 , edge-passivated dopants 41, 42 , adatom adsorptions 43, 44 , layer numbers 45 , stacking configurations 46 , surface curvatures 47, 48 , mechanical strains 49, 50 , electric fields 51–53 , and magnetic fields 32, 54, 55 . GNRs are expected to be more potentially applicable in future nanodevices 15, 56, 57 .…”