Crystallization-dependent 100-nm periodic structures on gold and graphene based on femtosecond laser irradiation

Laser-induced periodic surface structures (LIPSS), particularly those exhibiting high-spatial frequency LIPSS (HSFL), hold paramount significance in precision manufacturing due to their capacity for rapid nanostructure generation. However, in the case of Au, a material widely employed in micro-nano applications, the manifestation of HSFL remains predominantly elusive. This study successfully fabricated HSFL with a periodicity of 100 nm on Au, leveraging the crystallization induced by a 520-nm femtosecond laser (fs-laser). The fundamental element for instigating HSFL formation resides in exploiting “amorphous Au” with disordered lattice structures coupled with the fs-laser-induced crystallization. The disordered lattice structures facilitated the dominance of electron–phonon coupling in the thermal transport, suppressing the hot-electron diffusion effect—a prerequisite for HSFL formation. The crystallization controlled the conversion of “amorphous Au” into the typical crystalline state of Au while also enabling period multiplication contingent on the number of fs-laser pulses. It ultimately facilitated the formation of a 100-nm HSFL on crystalline Au. Furthermore, the versatility of Au HSFL was demonstrated through its application in periodic nanopatterning (i.e., HSFL) on single-layer graphene. Therefore, besides unveiling novel physical mechanisms underpinning the formation of metal HSFL, the attainment of Au HSFL undoubtedly promises significant advancements in nanoelectronics and nanophotonics.