Visualizing grain boundaries in monolayer MoSe2 using mild H2O vapor etching  

作　　者：Jinhuan Wang Xiaozhi Xu Ruixi Qiao Jing Liang Can Liu Bohao Zheng Lei Liu Peng Gao Qingze Jiao Dapeng Yu Yun Zhao Kaihui Liu 

机构地区：[1]School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China [2]State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, 8eijing 100871, China [3]Department of Materials Science and Engineering, College of Engineering, Peking University, 8eijing 100871, China [4]International Centre for Quantum Materials, and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 10087 I, China [5]Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China [6]Collaborative Innovation Centre of Quantum Matter, Beijing 100871, China [7]Jinhuan Wang, Xiaozhi Xu and Ruixi Qiao contributed equally to this work.

出　　处：《Nano Research》2018年第8期4082-4089,共8页纳米研究（英文版）

摘　　要：Beyond graphene, two-dimensional （2D） transition metal dichalcogenides （TMDs） have attracted significant attention owing to their potential in next-generation nanoelectronics and optoelectronics. Nevertheless, grain boundaries are ubiquitous in large-area as-grown TMD materials and would significantly affect their band structure, electrical transport, and optical properties. Therefore, the characterization of grain boundaries is essential for engineering the properties and optimizing the growth in TMD materials. Although the existence of boundaries can be measured using scanning tunneling microscopy, transmission electron microscopy, or nonlinear optical microscop~ a universal, convenient, and accurate method to detect boundaries with a twist angle over a large scale is still lacking. Herein, we report a high-throughput method using mild hot H20 etching to visualize grain boundaries of TMDs under an optical microscope, while ensuring that the method is nearly noninvasive to grain domains. This technique utilizes the reactivity difference between stable grain domains and defective grain boundaries and the mild etching capacity of hot water vapor. As grain boundaries of two domains with twist angles have defective lines, this method enables to visualize all types of grain boundaries unambiguously. Moreover, the characterization is based on an optical microscope and therefore naturally of a large scale. We further demonstrate the successful application of this method to other TMD materials such as MoS2 and WSe2. Our technique facilitates the large-area characterization of grain boundaries and will accelerate the controllable growth of large single-crystal TMDs.Beyond graphene, two-dimensional （2D） transition metal dichalcogenides （TMDs） have attracted significant attention owing to their potential in next-generation nanoelectronics and optoelectronics. Nevertheless, grain boundaries are ubiquitous in large-area as-grown TMD materials and would significantly affect their band structure, electrical transport, and optical properties. Therefore, the characterization of grain boundaries is essential for engineering the properties and optimizing the growth in TMD materials. Although the existence of boundaries can be measured using scanning tunneling microscopy, transmission electron microscopy, or nonlinear optical microscop~ a universal, convenient, and accurate method to detect boundaries with a twist angle over a large scale is still lacking. Herein, we report a high-throughput method using mild hot H20 etching to visualize grain boundaries of TMDs under an optical microscope, while ensuring that the method is nearly noninvasive to grain domains. This technique utilizes the reactivity difference between stable grain domains and defective grain boundaries and the mild etching capacity of hot water vapor. As grain boundaries of two domains with twist angles have defective lines, this method enables to visualize all types of grain boundaries unambiguously. Moreover, the characterization is based on an optical microscope and therefore naturally of a large scale. We further demonstrate the successful application of this method to other TMD materials such as MoS2 and WSe2. Our technique facilitates the large-area characterization of grain boundaries and will accelerate the controllable growth of large single-crystal TMDs.

关 键 词：MoSez grain boundar3 hot water vapor single crystal 

分 类 号：TN405.982[电子电信—微电子学与固体电子学] TK123[动力工程及工程热物理—工程热物理]