JARA-FIT and second Institute of Physics , RWTH Aachen University , 52056 Aachen , Germany.
Peter Grünberg Institute (PGI-8/9) , Forschungszentrum Jülich , 52425 Jülich , Germany.
Nano Lett. 2018 Mar 14;18(3):1707-1713. doi: 10.1021/acs.nanolett.7b04774. Epub 2018 Feb 16.
There are a number of theoretical proposals based on strain engineering of graphene and other two-dimensional materials, however purely mechanical control of strain fields in these systems has remained a major challenge. The two approaches mostly used so far either couple the electrical and mechanical properties of the system simultaneously or introduce some unwanted disturbances due to the substrate. Here, we report on silicon micromachined comb-drive actuators to controllably and reproducibly induce strain in a suspended graphene sheet in an entirely mechanical way. We use spatially resolved confocal Raman spectroscopy to quantify the induced strain, and we show that different strain fields can be obtained by engineering the clamping geometry, including tunable strain gradients of up to 1.4%/μm. Our approach also allows for multiple axis straining and is equally applicable to other two-dimensional materials, opening the door to investigating their mechanical and electromechanical properties. Our measurements also clearly identify defects at the edges of a graphene sheet as being weak spots responsible for its mechanical failure.
有许多基于应变工程的石墨烯和其他二维材料的理论方案，但这些系统中应变场的纯机械控制仍然是一个主要挑战。到目前为止，这两种方法主要要么同时耦合系统的电学和力学性能，要么由于基底而引入一些不必要的干扰。在这里，我们报告了硅微加工梳状驱动器，以完全机械的方式可控且可重复地在悬浮的石墨烯片上诱导应变。我们使用空间分辨共焦拉曼光谱来量化所诱导的应变，并且我们表明可以通过设计夹持几何形状来获得不同的应变场，包括高达 1.4%/μm 的可调应变梯度。我们的方法还允许进行多轴应变，并且同样适用于其他二维材料，为研究它们的力学和机电性能开辟了道路。我们的测量还清楚地确定了石墨烯片边缘的缺陷是导致其机械失效的薄弱点。
