Electron transport in a stressed moiré bigraphene structure

Abstract

Within the framework of density functional theory in combination with the method of nonequilibrium Green's functions, the transport characteristics (band structure, transmission spectrum, current–voltage characteristic, and differential conductivity) of unstressed, stressed, and strongly stressed moiré bigraphene nanodevices with interlayer distances of 3.4 Å, 2.85 Å, and 1.7 Å, respectively, and consisting of two layers of graphene, where one of the layers is connected to electrodes (active graphene) and the other layer is electrically neutral (passive graphene) have been determined. It is established that, when passive graphene is twisted to certain angles before the moiré pattern is obtained (∼4° and ∼ 12°), the energy gap is opened, the value of range 1.66–1.82 eV and 3.78–4.69 eV in the unstressed state (in the stressed state 2.27–2.67 eV and 4.28–4.93 eV), respectively. It is shown that the transmission spectrum of bilayer graphene has features in the form of peak structures; with decreasing intergraphene distance these structures begin to blur and their quasiperiodic behavior is partially broken. The current–voltage characteristic of such nanostructures has areas with negative differential conductivity. Such nonlinear behavior of transport characteristics of bigraphene moiré structures can be used for the construction of electronic components of nanoelectronics on their basis.