Nanosecond laser treatment of graphene

TL;DR

This study investigates the effects of nanosecond laser pulses on CVD graphene, revealing damage thresholds, fluorescence signals from oxidized residues, and implications for laser-based graphene processing techniques.

Contribution

It provides new insights into the damage thresholds and fluorescence responses of graphene under nanosecond laser irradiation, which was previously less understood.

Findings

Damage threshold energy density is approximately 200 mJ/cm2.

UV irradiation has a lower damage threshold depending on sample origin.

Damaged areas exhibit strong fluorescence due to oxidized graphene residues.

Abstract

Laser processing of graphene is of great interest for cutting, patterning and structural engineering purposes. Tunable nanosecond lasers have the advantage of being relatively widespread (compared to e.g. femtosecond or high-power continuous wave lasers). Hereby we have conducted an investigation of the impact of nanosecond laser pulses on CVD graphene. The damage produced by sufficiently strong single shots (pulse width 5 ns, wavelength 532 or 266 nm) from tunable optical parametric oscillator was investigated by the methods of scanning electron microscopy and optical microspectroscopy (Raman and fluorescence). Threshold of energy density for producing visible damage was found to be ~200 mJ/cm2. For UV irradiation the threshold could be notably less depending on the origin of sample. Surprisingly strong fluorescence signal was recorded from damaged areas and is attributed to the residues of oxidized graphene.