Mono-Mono-Mono and Bi-Bi-Bi three-layer graphene systems’ optical conductivity

Investigating the longitudinal optical conductivity of graphene systems, which is the most important property for opto-electronic devices, for three-layer graphene systems theoretically and numerically is the main purpose of this study. Each layer can be mono- or bi-layer graphene. Separation between layers has been denoted by d, selected to be about ten nanometers. The carrier densities in each layer can be tuned by changing gate voltage. In these two dimensional layered structures; the main contributions to the optical conductivity are from the intra- and inter-band transition channels in a same layer. In this paper the graphene structure is described primarily, and the three-layer graphene systems with composes of mono-mono-mono and bi-bi-bi has been defined. Using dielectric and electron density-density correlation tensors, the imaginary part of dielectric function for the three-layer graphene systems are calculated and optical conductivities are plotted as a function of photon energies in different broadening widths, for final stages.