Nanoscale strainability of graphene by laser shock-induced three-dimensional shaping.

Graphene has many promising physical properties. It has been discovered that local strain in a graphene sheet can alter its conducting properties and transport gaps. It is of great importance to develop scalable strain engineering techniques to control the local strains in graphene and understand the limit of the strains. Here, we present a scalable manufacturing process to generate three-dimensional (3D) nanostructures and thus induce local strains in the graphene sheet. This process utilizes laser-induced shock pressure to generate 3D tunable straining in the graphene sheet. The size dependent straining limit of the graphene and the critical breaking pressure are both studied. It is found that the graphene film can be formed to a circular mold (∼50 nm in diameter) with an aspect ratio of 0.25 and strain of 12%, and the critical breaking pressure is 1.77 GPa. These values were found to be decreasing with the increase of mold size. The local straining and breaking of graphene film are verified by Raman spectra. Large scale processing of the graphene sheet into nanoscale patterns is presented. The process could be scaled up to roll-to-roll process by changing laser beam size and scanning speed. The presented laser shock straining approach is a fast, tunable, and low-cost technique to realize strain engineering of graphene for its applications in nanoelectrical devices.