Highly tunable charge transport in defective graphene nanoribbons under external local forces and constraints: A hybrid computational study

TL;DR

This study combines molecular mechanics and tight-binding models to analyze how local forces, constraints, and vacancy defects affect the electronic transport properties of graphene nanoribbons, revealing tunable conductance and energy gaps.

Contribution

It introduces a hybrid modeling approach to study mechanical and defect effects on electronic transport in graphene nanoribbons, enabling tunable conductance control.

Findings

Vacancy defects open an energy gap, turning metal into semiconductor.

Increasing defects enlarges the energy gap.

Local forces decrease conductance and energy gap.

Abstract

In this paper, we propose a combined modeling of molecular mechanics (MM) and the tight-binding (TB) approach, which enables us to study the effect of factors such as external local forces, constraints, and vacancy defects on electronic transport properties of nanomaterials. Nanostructures selected in this work are armchair graphene nanoribbons (AGNRs). According to this method, the nanostructure is modeled as a frame, and the beam element is applied for illustrating the covalent interatomic interactions in bonds. In our calculations, the terms of torsional, stretching, and bending energies are considered. The selected pristine nanoribbon is a metal, and the purpose of this study is to find the effects of mechanical loading, the vacancy defects and their positions on the electrical conductance of the structure. We observe that the presence of vacancy defects in the structure leads to the opening of an energy gap, which changes the phase of the nanostructure from metal to the semiconductor. We find that with increasing the number of point defects, the energy gap size of the strained system grows. Besides, increasing the magnitude of the local force reduces the conductance, and the energy gap of the system. By changing parameters such as the number of point defects and magnitude local forces, the transport gap of the system can be controlled. The results of this research may be useful in the design of nanoelectromechanical systems.