Coexistence of doping and strain to tune electronic and optical properties of monolayer graphene

Abstract

We performed first-principles calculations to study the structural, electronic and optical properties of monolayers graphene through strain and Al atoms doping with different concentrations. The results show that band gap of pristine graphene and graphene doped with 3.at% of Al consistently increases with strain, whereas the band gap of graphene doped with 6 at%, 9 at%, and 12 at% of Al initially increases and subsequently decreases as strain is introduced, and the band gap characteristics change from direct to indirect.Notably, a flat band phenomenon was found when the strain of 6.at%Al doped graphene reached 10 %. Furthermore, the study of optical properties reveals that the increase of Al doping concentration leads to a redshift of the peak in the imaginary part of the dielectric constant of graphene. This not only reduces reflectance to ultraviolet light but also enhances absorption of visible light while decreasing transmittance within the infrared and visible light ranges. Additionally, strain further induces a redshift in the imaginary part of the dielectric constant of Al-doped graphene.