Nanoprocessing of Self-Suspended Monolayer Graphene and Defect Formation by Femtosecond-Laser Irradiation

We demonstrate the femtosecond-laser processing of self-suspendedmonolayer graphene grown by chemical vapor deposition, resulting inmultipoint drilling with holes having a diameter of <100 nm. Scanningtransmission electron microscopy revealed the formation of many nanoporeson the laser-irradiated graphene. Furthermore, atomic-level defectsas well as nanopores were found in the graphene membrane by high-resolutiontransmission electron microscopy, while the overall crystal structureremained intact. Raman spectroscopy showed an increase in the defectdensity with an increase in the number of laser shots, suggestingthat the nanopore formation triggered the creation of the <100nm holes. The approach presented herein can offer an experimentalinsight into the simulation of atomic dynamics in graphene under femtosecond-laserirradiation. The thorough examination of the atomic defect formationand secondary effect of surface cleaning observed in this study wouldhelp develop engineering methods for graphene and other two-dimensionalmaterials in the future.

Automated summary

We used femtosecond-laser processing to drill nanopores and <100 nm holes in self-suspended monolayer graphene. The resulting defects were examined using scanning transmission electron microscopy and Raman spectroscopy. This study provides experimental insight into atomic dynamics in graphene under laser irradiation and can help develop engineering methods for graphene and other two-dimensional materials in the future.