Al/Si dopants effect on the electronic and optical behaviors of graphene mono-layers useful for infrared detector devices

Abstract

Two-dimensional (2D) graphene with different forms is a prosperous class of materials beneficial in nano-electronics, and infrared-detector devices. Herein, we analyze the electronic and optical behaviours of electron acceptor (Al)- and isovalent (Si) inserted into graphene sheets, which are computed by utilizing ab-initio simulations. We find that the individual doping impurities of Al or Si atoms onto monolayer graphene result in p-type and semiconducting behaviours, respectively, attributed to the contribution of the valence electrons number of these atoms to the host 2D honeycomb lattice of graphene. Even though the Al atom contributing one less electron to the host lattice, both individual impurities of the Al- or Si-doped materials are found to cause a splitting in the valence states and conduction states at the K-point, leading to the opening of the Dirac cone. In monolayer graphene, doping two Al atoms into the nearest neighbour sites creates a trivial metallic system, while doping two Si atoms into the nearest neighbour sites causes the Dirac cone to re-emerge. Owing to the stark difference in the electronic structure results of mono- and double-atom substitution of Al/Si in graphene single-layers, we find different optical behaviours in these doped systems. Additionally, X-ray absorption spectroscopy simulations are employed to inspect the core-level spectra of pure and substitutional doped graphene single layers. Accordingly, the optical spectral features of graphene single-layers substituted with foreign impurities, such as Al/Si have revealed the tailoring of optical absorption from the infrared to the visible windows. Due to the outstanding characteristics of this 2D dimensional gapless graphene, our simulated results could provide a guidance for future experimental investigations into the fabrication of doped graphene sheets suitable for infrared detectors, photonics, and modern optoelectronic devices integrated into advanced technologies.