title: Stretch-induced stiffness enhancement of graphene grown by chemical vapor deposition.
abstract: The mechanical properties of ultrathin membranes have attracted considerable attention recently. Nanoindentation based on atomic force microscopy is commonly employed to study mechanical properties. We find that the data processing procedures in previous studies are nice approximations, but it is difficult for them to illustrate the mechanical properties precisely. Accordingly, we develop a revised numerical method to describe the force curve properly, by which the intrinsic mechanical properties of these membranes can be acquired. Combining the nanoindentation measurements with the revised numerical method, we demonstrate that loading-unloading cycles under large load can lead to a pronounced improvement in stiffness of graphene grown by chemical vapor deposition (CVD). The Young's moduli of the stretched CVD graphene membranes can be improved to ∼1 TPa, closing to the value of the pristine graphene. Our findings demonstrate a possible way to recover the exceptional elastic properties of CVD graphene from the softened stiffness caused by wrinkles.
authors: State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, People's Republic of China.
authors: Qing-Yuan
authors: QY
authors: Lin
authors: Guangyin
authors: G
authors: Jing
authors: Yang-Bo
authors: YB
authors: Zhou
authors: Yi-Fan
authors: YF
authors: Wang
authors: Jie
authors: J
authors: Meng
authors: Ya-Qing
authors: YQ
authors: Bie
authors: Da-Peng
authors: DP
authors: Yu
authors: Zhi-Min
authors: ZM
authors: Liao