Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907, United States.
Nano Lett. 2012 Sep 12;12(9):4577-83. doi: 10.1021/nl301817t. Epub 2012 Aug 16.
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.
石墨烯具有许多有前途的物理特性。已经发现，石墨烯片的局部应变可以改变其导电性能和传输间隙。开发可扩展的应变工程技术来控制石墨烯中的局部应变并了解应变的极限非常重要。在这里，我们提出了一种可扩展的制造工艺，用于生成三维（3D）纳米结构，从而在石墨烯片上产生局部应变。该工艺利用激光诱导的冲击波压力在石墨烯片上产生 3D 可调应变。研究了石墨烯的应变极限和临界破坏压力的尺寸依赖性。结果发现，石墨烯膜可以被形成具有 0.25 的纵横比和 12%应变的圆形模具（直径约为 50nm），临界破坏压力为 1.77GPa。这些值随着模具尺寸的增加而减小。通过拉曼光谱验证了石墨烯膜的局部应变和断裂。提出了将石墨烯片大规模加工成纳米级图案的方法。通过改变激光束的尺寸和扫描速度，可以将该工艺扩展到卷对卷工艺。所提出的激光冲击应变方法是一种快速、可调谐且低成本的技术，可实现石墨烯的应变工程，从而将其应用于纳米电子器件。
