Giant enhancement of Piezo-resistance in ballistic graphene due to transverse electric fields

TL;DR

This study predicts a giant enhancement of piezoresistance in ballistic graphene, especially in the transverse direction, due to electric field effects, with potential applications in nanoelectromechanical systems.

Contribution

The paper introduces a new methodology combining tight binding and quantum transport to evaluate piezoresistance in graphene, revealing a significant transverse gauge factor variation.

Findings

Transverse gauge factor varies by approximately 1000% compared to longitudinal.

Longitudinal gauge factor is about 0.3, transverse about -3.3.

Sign inversion observed in the transverse gauge factor.

Abstract

We investigate the longitudinal and transverse piezoresistance effect in suspended graphene in the ballistic regime. Utilizing parametrized tight binding Hamiltonian from ab initio calculations along with Landauer quantum transport formalism, we devise a methodology to evaluate the piezoresistance effect in 2D materials especially in graphene. We evaluate the longitudinal and transverse gauge factor of graphene along armchair and zigzag directions in the linear elastic limit ($0\%$-$10\%$). The longitudinal and transverse gauge factors are identical along armchair and zigzag directions. Our model predicts a significant variation ($\approx 1000\% $ change) in transverse gauge factor compared to longitudinal gauge factor along with sign inversion. The calculated value of longitudinal gauge factor is $\approx 0.3$ whereas the transverse gauge factor is $\approx -3.3$. We rationalize our prediction using deformation of Dirac cone and change in separation between transverse modes due to longitudinal and transverse strain, leading to an inverse change in gauge factor. The results obtained herein may serve as a template for high strain piezoresistance effect of graphene in nano electromechanical systems.