School of Applied and Engineering Physics, Kavli Institute at Cornell for Nanoscale Science, Cornell University , Ithaca, New York 14853, United States.
Nano Lett. 2011 Mar 9;11(3):1232-6. doi: 10.1021/nl1042227. Epub 2011 Feb 4.
Graphene's unparalleled strength, stiffness, and low mass per unit area make it an ideal material for nanomechanical resonators, but its relatively low quality factor is an important drawback that has been difficult to overcome. Here, we use a simple procedure to fabricate circular mechanical resonators of various diameters from graphene grown by chemical vapor deposition. In addition to highly reproducible resonance frequencies and mode shapes, we observe a striking improvement of the membrane quality factor with increasing size. At room temperature, we observe quality factors as high as 2400 ± 300 for a resonator 22.5 μm in diameter, about an order of magnitude greater than previously observed quality factors for monolayer graphene. Measurements of quality factor as a function of modal frequency reveal little dependence of Q on frequency. These measurements shed light on the mechanisms behind dissipation in monolayer graphene resonators and demonstrate that the quality factor of graphene resonators relative to their thickness is among the highest of any mechanical resonator demonstrated to date.
石墨烯具有无与伦比的强度、硬度和单位面积的低质量，使其成为纳米机械谐振器的理想材料，但相对较低的品质因数是一个重要的缺点，一直难以克服。在这里，我们使用一种简单的方法从化学气相沉积生长的石墨烯制备各种直径的圆形机械谐振器。除了具有高度可重复的共振频率和模式形状外，我们还观察到膜的品质因数随尺寸的增加而显著提高。在室温下，我们观察到直径为 22.5 μm 的谐振器的品质因数高达 2400±300，比以前观察到的单层石墨烯的品质因数高一个数量级。对品质因数随模态频率的测量表明，Q 值对频率的依赖性很小。这些测量揭示了单层石墨烯谐振器中耗散的机制，并表明与厚度相比，石墨烯谐振器的品质因数是迄今为止所展示的任何机械谐振器中最高的之一。
