A gate-induced switch in zigzag graphene nanoribbons and charging effects
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Updated: Jun 13, 2026

Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Hosein Cheraghchi1, Hanyieh Esmailzade
1School of Physics, Damghan University of Basic Sciences, PO Box 36715-364, Damghan, Iran. cheraghchi@dubs.ac.ir
Abstract:
Using the non-equilibrium Green's function formalism, we investigate nonlinear transport and charging effects of gated graphene nanoribbons (GNRs) with an even number of zigzag chains. We find a negative differential resistance (NDR) over a wide range of gate voltages with an on/off ratio approximately 10(6) for narrow enough ribbons. This NDR originates from the parity selection rule and also prohibition of transport between discontinuous energy bands. Since the external field is well screened close to the contacts, the NDR is robust against the electrostatic potential. However, for voltages higher than the NDR threshold, due to charge transfer through the edges of the zigzag GNR (ZGNR), screening is reduced such that the external potential can penetrate inside the ribbon giving rise to smaller values of off-current. Furthermore, the on/off ratio of the current depends on the aspect ratio of the length/width and also edge impurity. Moreover, the on/off ratio displays a power law behavior as a function of ribbon length.
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