Electronic Structure and Carrier Mobilities of Twisted Graphene Helix

TL;DR

This study explores how twisting affects the electronic properties and carrier mobilities of armchair graphene nanoribbons, revealing that twisting can be used to tune their electronic behavior for potential mechanical switching applications.

Contribution

It provides a detailed analysis of the impact of twisting on electronic structure and mobilities of AGNRs using DFT and deformation potential theory, highlighting new ways to control their properties.

Findings

Twisting influences effective mass and mobility more than electron-phonon interactions.

N=3n+2 HAGNRs have hole mobility close to intrinsic graphene, enhanced by fluorine passivation.

N=8 F-passivated AGNRs are highly responsive to torsional strain, suitable for high-frequency switching.

Abstract

We have investigated the effect of twisting on electronic band structure, effective mass and carrier mobilities of three prototypes of AGNRs (N=6, 7 & 8) using Density functional theory combined with Deformation potential theory and Effective mass approximation. It is shown that the influence of twisted modes electron-phonon interaction is smaller than stretching modes, nonetheless, twisting has a profound effect on effective mass and mobilities. Similar to earlier reported conclusion in which the ideal N=3n wide HAGNR potentially exhibit an electron mobility comparable to intrinsic graphene, we also found that the ideal N=3n+2 HAGNRs hole mobility reside more closely to intrinsic graphene which could be increased further through Fluorine passivation. Thus, the control of the ribbon width along with passivation and extent of deformation are of paramount importance for determining the n-type or p-type of ribbons. Also, because of strong response to torsional strain, the N=8 F passivated AGNRs are the most appropriate for mechanical and high frequency switching. Our results suggest that twisting a ribbon can be considered as a good alternative way for controlled manipulation of the band structure and carrier mobilities for applications in mechanical switching devices.