Zhang Chenxi, Song Jizhou, Yang Qingda
Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL 33146, USA.
Nanotechnology. 2014 Nov 7;25(44):445401. doi: 10.1088/0957-4484/25/44/445401. Epub 2014 Oct 14.
Graphene/hexagonal boron nitride (h-BN) heterostructure has showed great potential to improve the performance of a graphene device. A graphene on an h-BN substrate may buckle due to the thermal expansion mismatch between the graphene and h-BN. We used an energy method to investigate the periodic buckling patterns including one-dimensional, square checkerboard, hexagonal, equilateral triangular and herringbone mode in a graphene/h-BN heterostructure under equi-biaxial compression. The total energy, consisting of cohesive energy, graphene membrane energy and graphene bending energy, for each buckling pattern is obtained analytically. At a compression slightly larger than the critical strain, all buckling patterns have the same total energies, which suggests that any buckling pattern may occur. At a compression much larger than the critical strain, the herringbone mode has the lowest total energy by significantly reducing the membrane energy of graphene at the expense of a slight increase of the bending energy of graphene and cohesive energy. These results may serve as guidelines for strain engineering in graphene/h-BN heterostructures.
石墨烯/六方氮化硼（h-BN）异质结构在提升石墨烯器件性能方面展现出了巨大潜力。由于石墨烯与h-BN之间的热膨胀失配，h-BN衬底上的石墨烯可能会发生翘曲。我们采用能量方法研究了在等双轴压缩下石墨烯/h-BN异质结构中的周期性翘曲模式，包括一维、方形棋盘格、六边形、等边三角形和人字形模式。通过解析得到了每种翘曲模式的总能量，其由内聚能、石墨烯薄膜能和石墨烯弯曲能组成。在压缩量略大于临界应变时，所有翘曲模式具有相同的总能量，这表明任何一种翘曲模式都可能出现。在压缩量远大于临界应变时，人字形模式具有最低的总能量，这是通过显著降低石墨烯的薄膜能来实现的，代价是石墨烯弯曲能和内聚能略有增加。这些结果可为石墨烯/h-BN异质结构中的应变工程提供指导。
