Strain-induced switching in field effect transistor based on zigzag graphene nanoribbons

Abstract

In this paper, we investigate the effects of uniaxial and oblique strain on Non-linear transport of zigzag graphene nanoribbons using non-equilibrium Green's function formalism. The current-voltage characteristics and especially negative differential resistance (NDR) are affected by the type, strength, and direction of the applied strain. For the tensile strain along the ribbon axis, the on-off current ratio increases, while for the compressive strain, NDR gradually disappears. In the oblique strain, the on-off current ratio drastically decreases compared to the un-strained case. In context, we demonstrate how strain can affect band structure and transition rules as well as transmission coefficients. Also in our calculations, we consider Coulomb interaction as long-range electrostatic potential at mean-field approximation. Coulomb interaction decreases off current and leads to the increased on-off current ratio in the oblique strain. Here, we observe under the influence of the oblique strain, the geometrical symmetry is broken, so the symmetry of charge profile and local currents are broken across ZGNR. We show an imbalanced accumulated charge located on the nanoribbon edges that as a consequence, appear some transverse local currents between the upper and lower edges. These transverse local currents are increased by the strain strength. The minimum (maximum) imbalanced charge accumulated on the ribbon edges occurs exactly at the on (off)-state of longitudinal bias where the transverse current is decreasing (increasing). Finally, we strongly suggest the strain can operate as a nanoelectromechanical switch.