DFT study on electronic and optical properties of graphene under an external electric field

Abdelhafid Najim,Omar Bajjou,Lhouceine Moulaoui,Khalid Rahmani,Mustapha Boulghallat,B Benhala,K Mansouri,M Qbadou,A Raihani

doi:10.1051/e3sconf/202233600006

Abdelhafid Najim, Omar Bajjou + Show 7 more

Open Access

https://doi.org/10.1051/e3sconf/202233600006

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Journal: E3S Web of Conferences	Publication Date: Jan 1, 2022
Citations: 2	License type: CC BY 4.0

Affiliation: Université Sultan Moulay Slimane

Abstract

The paper investigates the electronic and optical properties of graphene, under the external electric field (Eext) according to perpendicular direction, using density functional theory (DFT). Applying the Eext to the graphene sheet modifies its electronic and optical properties, including the band gap energy, total density of states (TDOS), absorption coefficient, dielectric function, and refractive index. Graphene’s band gap is opened by the application of Eext to its structure. As a result of the effect of Eext on graphene layer, its absorption coefficient increases in the ultraviolet (UV) range and decreases in the visible range. We found that the electronic and optical properties of graphene material, can be altered by a perpendicular excitation applied to its structure.

Highlights

Graphene is a semimetal that has zero band gap at the Dirac point
In the carbon atoms of graphene sheets, three atomic orbitals, 2s, 2px, and 2py are hybridized to form three sp2 hybrid orbitals, and the 2pz orbital remains perpendicular to the other orbitals
Due to the increase of band gap energy, the probability of electrons for occupying near the Fermi level is reduced by reason of the influence of Eext

Summary

Introduction

Graphene is a semimetal that has zero band gap at the Dirac point. The electronic states can be well described by the tight binding Hamiltonian of π electrons in carbon atoms [2]. In the carbon atoms of graphene sheets, three atomic orbitals, 2s, 2px, and 2py are hybridized to form three sp hybrid orbitals, and the 2pz orbital remains perpendicular to the other orbitals. In the hybridized orbitals there are three σ bonds between the adjacent carbon atoms, and the 2pz orbital results in the π bonds. The nearly sp hybridized carbon in the graphene layer supports good electronic conductivity. The importance of graphene materials has promoted major research in various fields, such as optoelectronic devices [3]

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