Quantum transport properties of AB bilayer graphene via tight-binding approach with NEGF formalisms

AB-stacked bilayer graphene has garnered significant scientific interest owing to its superior electron transport properties, even when compared to monolayer graphene; these superior properties are attributed to the additional π orbital overlaps in the x–y plane. In this study, the nearest-neighbour tight-binding (NNTB) model for AB-stacked bilayer graphene was developed. Using this NNTB approximation, a numerical analysis simulator using non-equilibrium Green’s function (NEGF) equations to describe the quantum transport properties of electrons in the bilayer graphene lattice potential was developed using MATLAB. Based on these numerical analysis simulations, various metrics of interest such as the E-K dispersion relation, density of states (DOS), and transmission coefficients were obtained for each specified lattice width and length. Furthermore, the electronic transport properties of two variants of bilayer graphene—zigzag edge and armchair edge variants—were examined in these simulations. The dispersion relation of the zigzag edge variant exhibited no bandgap, whereas the armchair edge variant exhibited an alternating trend of semiconductor behaviour from the 3n − 1 and 3n series and metallic behaviour for the 3n + 1 series; this is consistent with contemporary research. Furthermore, the DOS simulations revealed the existence of a significant concentration of quantum states in the mid-band for the zigzag edge variant; by contrast, for the armchair edge variant, the number of states was the largest at the first quartile-band and the third quartile-band region. The transmission coefficients for both the zigzag and armchair edge variants featured similar distributions throughout the energy spectrum.  However, for the zigzag edge variant, the coefficient was larger and the bandgap was tunable, with the bandgap at unity transmission ranging from 0 to 0.0484 eV or higher depending on the dimensions. These findings provide valuable insights into the electronic transport properties of bilayer graphene, highlighting its potential for advanced electronic applications.