ISI Foundation , Via Chisola 5 , 10126 Torino , Italy.
Center for Complexity and Biosystems, Department of Physics , University of Milano , Via Celoria 16 , 20133 Milano , Italy.
Nano Lett. 2018 Mar 14;18(3):2098-2104. doi: 10.1021/acs.nanolett.8b00273. Epub 2018 Mar 1.
Spatially nonuniform strain is important for engineering the pseudomagnetic field and band structure of graphene. Despite the wide interest in strain engineering, there is still a lack of control on device-compatible strain patterns due to the limited understanding of the structure-strain relationship. Here, we study the effect of substrate corrugation and curvature on the strain profiles of graphene via combined experimental and theoretical studies of a model system: graphene on closely packed SiO nanospheres with different diameters (20-200 nm). Experimentally, via quantitative Raman analysis, we observe partial adhesion and wrinkle features and find that smaller nanospheres induce larger tensile strain in graphene; theoretically, molecular dynamics simulations confirm the same microscopic structure and size dependence of strain and reveal that a larger strain is caused by a stronger, inhomogeneous interaction force between smaller nanospheres and graphene. This molecular-level understanding of the strain mechanism is important for strain engineering of graphene and other two-dimensional materials.
空间非均匀应变对于工程伪磁场和石墨烯能带结构非常重要。尽管人们对应变工程广泛关注，但由于对结构-应变关系的理解有限，仍然缺乏对设备兼容应变模式的控制。在这里，我们通过对一个模型系统（紧密堆积的 SiO 纳米球上的石墨烯，直径为 20-200nm）的实验和理论研究，研究了衬底波纹和曲率对石墨烯应变分布的影响。通过定量拉曼分析，我们观察到部分粘附和褶皱特征，并发现较小的纳米球会在石墨烯中产生更大的拉伸应变；理论上，分子动力学模拟证实了应变的相同微观结构和尺寸依赖性，并揭示了较小的纳米球与石墨烯之间更强、不均匀的相互作用力会导致更大的应变。这种对应变机制的分子水平理解对于石墨烯和其他二维材料的应变工程非常重要。
