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Nano Research

Article Title

Highly-anisotropic optical and electrical properties in layered SnSe

Authors

Shengxue Yang, Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA School of Materials Science and Engineering, Beihang University, Beijing 100191, China
Yuan Liu, Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA
Minghui Wu, Department of Physics, South University of Science and Technology of China, Shenzhen 518005, China
Li-Dong Zhao, School of Materials Science and Engineering, Beihang University, Beijing 100191, China
Zhaoyang Lin, Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
Hung-chieh Cheng, Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA
Yiliu Wang, Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
Chengbao Jiang, School of Materials Science and Engineering, Beihang University, Beijing 100191, China
Su-Huai Wei, Beijing Computational Science Research Center, Beijing 100094, China
Li Huang, Department of Physics, South University of Science and Technology of China, Shenzhen 518005, China
Yu Huang, Department of Materials Science and Engineering, University of California, Los Angeles, CA 90095, USA California Nanosystems Institute, University of California, Los Angeles, CA 90095, USA
Xiangfeng Duan, Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA California Nanosystems Institute, University of California, Los Angeles, CA 90095, USA

Keywords

layered SnSe, anisotropy, angle-resolved transports, polarized Raman scattering, angle-resolved optical absorption

Abstract

ABSTRACT Anisotropic materials are of considerable interest because of their unique combination of polarization- or direction-dependent electrical, optical, and thermoelectric properties. Low-symmetry two-dimensional (2D) materials formed by van der Waals stacking of covalently bonded atomic layers are inherently anisotropic. Layered SnSe exhibits a low degree of lattice symmetry, with a distorted NaCl structure and an in-plane anisotropy. Here we report a systematic study of the in-plane anisotropic properties in layered SnSe, using angle-resolved Raman scattering, optical absorption, and electrical transport studies. The optical and electrical characterization was direction-dependent, and successfully identified the crystalline orientation in the layered SnSe. Furthermore, the dependence of Raman-intensity anisotropy on the SnSe flake thickness and the excitation wavelength were investigated by both experiments and theoretical calculations. Finally, the electrical transport studies demonstrated that few-layer SnSe fieldeffect transistors (FETs) have a large anisotropic ratio of carrier mobility (~5.8) between the armchair and zigzag directions, which is a record high value reported for 2D anisotropic materials. The highly-anisotropic properties of layered SnSe indicate considerable promise for anisotropic optics, electronics, and optoelectronics.

Graphical Abstract

Publisher

Tsinghua University Press

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