Reversible hydrostatic strain in graphene/gold nanoparticles hybrid material induced by laser irradiation*

Gold nanoparticles (NPs) were prepared on SiO₂ substrate by local annealing of gold thin films using focused laser beam. CVD-grown graphene was transferred onto the prepared NPs. Subsequent Raman-spectroscopy measurements were performed on the samples using different laser powers. We used higher laser intensity (6 mW) to locally anneal the hybrid material. Low laser powers (0.6 mW) were used to characterize the doping and the strain formed in the same areas both before and after local heating. While we found that higher intensity laser irradiation increased gradually the doping and the defect concentration in SiO₂-supported graphene, the same irradiation procedure did not induce such irreversible effects in the graphene supported by Au NPs. Moreover, the laser irradiation induced dynamic hydrostatic strain in the graphene on Au NPs, which turned out to be completely reversible.
These results point out the role of the substrate in the resistance of graphene against laser irradiation, and can have implications in the development of graphene/plasmonic nanoparticle based high temperature sensors.