Highly-anisotropic optical and electrical properties in layered SnSe

• Published in: Nano research 2018, Vol.11 (1), p.554-564
• Main Authors: Yang, Shengxue, Liu, Yuan, Wu, Minghui, Zhao, Li-Dong, Lin, Zhaoyang, Cheng, Hung-chieh, Wang, Yiliu, Jiang, Chengbao, Wei, Su-Huai, Huang, Li, Huang, Yu, Duan, Xiangfeng
• Format: Article
• Language: English
• Subjects: Anisotropy; Atomic structure; Atomic/Molecular Structure and Spectra; Biomedicine; Biotechnology; Carrier mobility; Chemical bonds; Chemistry and Materials Science; Condensed Matter Physics; Electrical properties; Electrical studies; Field effect transistors; Materials Science; Nanotechnology; Optical properties; Optics; Optoelectronics; Raman spectra; Research Article; Semiconductor devices; Sodium chloride; Symmetry; Transport; 大各向异性; 性质; Raman; NaC1; 电子显示; 材料; 光吸收; 晶体管
• ISSN: 1998-0124; 1998-0000
• DOI: 10.1007/s12274-017-1712-2

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 NaC1 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 field- effect transistors （FETs） have a large anisotropic ratio of carrier mobility （N 5.8） bet- ween 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.