Laser-induced disassembly of a graphene single crystal into a nano-crystalline network

TL;DR

This study demonstrates how moderate laser irradiation can induce controlled disassembly of single crystal graphene into a nano-crystalline network, altering its structure and properties.

Contribution

It provides detailed insights into the time-dependent structural changes in graphene caused by laser irradiation, including bond-breaking and network formation.

Findings

Laser irradiation removes dopants from graphene.

Gradual formation of a nano-crystalline network occurs.

Structural changes enhance graphene's reactivity for sensor applications.

Abstract

We report about investigations of time-dependent structural modifications in single crystal graphene due to laser irradiation even at moderate power levels of 1mW in a diffraction limited spot. The structural modifications have been characterized by in situ scanning confocal Raman spectroscopy, atomic force height microscopy and transport studies. The time evolution of the Raman spectrum reveals two different effects: on a short time scale, dopants, initially present on the flake, are removed. The longer time scale behavior points to a laser induced gradual local decomposition of single crystal graphene into a network of interconnected nano-crystallites with a characteristic length scale of approximately 10 nm due to bond-breaking. The broken bonds offer additional docking sites for adsorbates as confirmed in transport and AFM height studies. These controlled structural modifications may for instance be valuable for enhancing the local reactivity and trimming graphene based gas sensors.