Unzipping graphene: Extendend defects by ion irradiation

TL;DR

This study demonstrates that oblique ion irradiation can create extended defects and fold graphene into nanoribbons, challenging assumptions about its radiation hardness and enabling controlled defect engineering.

Contribution

It reveals a novel method of defect creation in graphene via oblique ion irradiation, leading to controlled formation of extended defects and nanoribbons.

Findings

Graphene on dielectric substrates sustains major modifications under oblique ion irradiation.

Irradiation causes graphene to split and fold into nanoribbons along ion tracks.

Radiation hardness of graphene devices may be less than previously thought.

Abstract

Many of the proposed future applications of graphene require the controlled introduction of defects into its perfect lattice. Energetic ions provide one way of achieving this challenging goal. Single heavy ions with kinetic energies in the 100 MeV range will produce nanometer-sized defects on dielectric but generally not on crystalline metal surfaces. In a metal the ion-induced electronic excitations are efficiently dissipated by the conduction electrons before the transfer of energy to the lattice atoms sets in. Therefore, graphene is not expected to be irradiation sensitive beyond the creation of point defects. Here we show that graphene on a dielectric substrate sustains major modifications if irradiated under oblique angles. Due to a combination of defect creation in the graphene layer and hillock creation in the substrate, graphene is split and folded along the ion track yielding double layer nanoribbons. Our results indicate that the radiation hardness of graphene devices is questionable but also open up a new way of introducing extended low-dimensional defects in a controlled way.