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Nano Research

Article Title

Visualizing grain boundaries in monolayer MoSe2 using mild H2O vapor etching

Authors

Jinhuan Wang, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
Xiaozhi Xu, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Ruixi Qiao, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Jing Liang, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Can Liu, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Bohao Zheng, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
Lei Liu, Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, China
Peng Gao, International Centre for Quantum Materials, and Electron Microscopy Laboratory, School of Physics, Peking University, Beijing 100871, China
Qingze Jiao, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
Dapeng Yu, Department of Physics, South University of Science and Technology of China, Shenzhen 518055, China
Yun Zhao, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
Kaihui Liu, State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China Collaborative Innovation Centre of Quantum Matter, Beijing 100871, China

Keywords

MoSe2, grain boundary, hot water vapor, single crystal

Abstract

ABSTRACT 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 microscopy, 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 H2O 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.

Graphical Abstract

Publisher

Tsinghua University Press

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