Center for Multidimensional Carbon Materials, Institute for Basic Science (IBS) , Ulsan 44919, Republic of Korea.
ACS Nano. 2017 Jul 25;11(7):7084-7090. doi: 10.1021/acsnano.7b02716. Epub 2017 Jun 22.
Transition to a commensurate state changes the local symmetry periodicity on two-dimensional van der Waals superstructures, evoking distinctive properties far beyond individual layers. We investigate the morphology of moiré superstructures of graphene on hexagonal boron nitride (hBN) with a low twist angle (≈0°) through moiré fringe analyses with dark field transmission electron microscopy. The moiré fringes exhibit local variation, suggesting that the interaction between graphene and hBN depends on the stacking configuration and that local transition to the commensurate state occurs through the reduced crystalline mismatch (that is, by lattice stretching and twisting on the graphene lattices). This moiré superstructure analysis suggests an inventive method for studying the interaction between stacked van der Waals layers and for discerning the altered electronic and optical properties of graphene on hBN superstructures with a low twist angle, even at low magnification.
转变到相称状态会改变二维范德华超结构的局部对称周期性，从而激发出远超单个层的独特性质。我们通过暗场透射电子显微镜的莫尔条纹分析研究了具有低扭转角（≈0°）的六方氮化硼（hBN）上石墨烯的莫尔超结构的形态。莫尔条纹表现出局部变化，这表明石墨烯和 hBN 之间的相互作用取决于堆叠配置，并且通过减小的晶体失配（即通过在石墨烯晶格上拉伸和扭曲晶格）实现局部转变到相称状态。这种莫尔超结构分析为研究堆叠范德华层之间的相互作用以及识别具有低扭转角的 hBN 超结构上石墨烯的改变的电子和光学性质提供了一种有创意的方法，即使在低放大倍率下也是如此。
