The vacancy defect in graphene nano-ribbon field-effect transistor in the presence of an external perpendicular magnetic field

In this paper, we investigate effect of vacancy defect on graphene nano-ribbon field effect transistor (GNR-FET) in the presence of an external perpendicular magnetic field. Our simulation is based on Non-Equilibrium Green’s Function (NEGF). The nearest neighbor tight-binding model based on p_z orbital construct the device Hamiltonian. Also we calculate magnetoresistance (MR) for different position vacancies in presence B-field. We find an external B-field causes the conductance of the GNR increases, giving rise to the MR effect. The simulation results indicate in the presence of a small B-field the current is degraded because the vacancy defect act as scattering and the conductance decreases due to defects compared with the perfect nanoribbons and the MR is reduced but in the hall quantum regime the probability of being scattered by the vacancy reduced due to the electrons are more localized at edge states and this phenomena to enhance the MR ratio of the device. The results indicate that the defect near drain and near edge has the largest MR ratio in the presence of a small B-Field and in the hall quantum the defect near source has the largest MR ratio.