Tuning the electronic structure of graphene by ion irradiation

TL;DR

This study investigates how Ar+ ion irradiation introduces atomic-scale defects in graphene, significantly altering its electronic properties, especially reducing the Fermi velocity, as observed through microscopy and spectroscopy.

Contribution

It provides experimental insights into how ion-induced defects affect graphene's electronic structure, highlighting the role of disorder in modifying electron behavior.

Findings

Defects act as scattering centers and induce disorder in hopping amplitudes.

Ion irradiation causes a substantial reduction in Fermi velocity.

Defects modify local electronic properties observed via STM/STS.

Abstract

Mechanically exfoliated graphene layers deposited on SiO2 substrate were irradiated with Ar+ ions in order to experimentally study the effect of atomic scale defects and disorder on the low-energy electronic structure of graphene. The irradiated samples were investigated by scanning tunneling microscopy and spectroscopy measurements, which reveal that defect sites, besides acting as scattering centers for electrons through local modification of the on-site potential, also induce disorder in the hopping amplitudes. The most important consequence of the induced disorder is the substantial reduction in the Fermi velocity, revealed by bias-dependent imaging of electron-density oscillations observed near defect sites.