Effects due to backscattering and pseudogap features in graphene nanoribbons with single vacancies

TL;DR

This paper investigates how single vacancies in graphene nanoribbons affect electron backscattering and pseudogap formation, revealing the importance of confinement and geometry in these phenomena.

Contribution

It introduces a semiempirical model combined with Green's function methods to analyze backscattering and pseudogap features caused by vacancies in graphene nanoribbons.

Findings

Vacancies act as local charging centers inducing electrostatic inhomogeneities.

Pseudogaps with donor and acceptor characteristics can form near the first b1-b1* plateau.

Confinement and geometry significantly influence backscattering effects.

Abstract

We present a systematic study of electron backscattering phenomena during conduction for graphene nanoribbons with single-vacancy scatterers and dimensions within the capabilities of modern lithographic techniques. Our analysis builds upon an \textit{ab initio} parameterized semiempirical model that breaks electron-hole symmetry and nonequilibrium Green's function methods for the calculation of the conductance distribution $g$. The underlying mechanism is based on wavefunction localizations and perturbations that in the case of the first $\pi-\pi{}^*$ plateau can give rise to impurity-like pseudogaps with both donor and acceptor characteristics. Confinement and geometry are crucial for the manifestation of such effects. Self-consistent quantum transport calculations characterize vacancies as local charging centers that can induce electrostatic inhomogeneities on the ribbon topology.