Near‐Unity Polarization of Valley‐Dependent Second‐Harmonic Generation in Stacked TMDC Layers and Heterostructures at Room Temperature

With unique valley‐dependent optical and optoelectronic properties, 2D transition metal dichalcogenides (2D TMDCs) are promising materials for valleytronics. Second‐harmonic generation (SHG) in 2D TMDCs monolayers has shown valley‐dependent optical selection rules. However, SHG in monolayer TMDCs is...

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Published in:Advanced materials (Weinheim) 2020-07, Vol.32 (29), p.e1908061-n/a
Main Authors: Zhang, Danliang, Zeng, Zhouxiaosong, Tong, Qingjun, Jiang, Ying, Chen, Shula, Zheng, Biyuan, Qu, Junyu, Li, Fang, Zheng, Weihao, Jiang, Feng, Zhao, Hepeng, Huang, Lanyu, Braun, Kai, Meixner, Alfred J., Wang, Xiao, Pan, Anlian
Format: Article
Language:English
Subjects:
Harmonic generations
Heterostructures
Interlayers
inversion symmetry breaking
Materials science
Monolayers
Multilayers
Optical properties
Optoelectronics
Polarization
Room temperature
Symmetry
Temperature dependence
Transition metal compounds
transition metal dichalcogenides
Valleys
valley‐dependent second‐harmonic generation
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Summary:With unique valley‐dependent optical and optoelectronic properties, 2D transition metal dichalcogenides (2D TMDCs) are promising materials for valleytronics. Second‐harmonic generation (SHG) in 2D TMDCs monolayers has shown valley‐dependent optical selection rules. However, SHG in monolayer TMDCs is generally weak; it is important to obtain materials with both strong SHG signals and a large degree of polarization. In the work, a variety of inversion‐symmetry‐breaking (3R‐like phase) TMDCs (WSe2, WS2, MoS2) atomic layers, spiral structures, and heterostructures are prepared, and their SHG polarization is studied. Through circular‐polarization‐resolved SHG experiments, it is demonstrated that the SHG intensity is enhanced in thicker samples by breaking inversion symmetry while maintaining the degree of polarization close to unity at room temperature. By studying TMDCs with different twist angles and the spiral structures, it is found that there is no significant effect of multilayer interlayer interaction on valley‐dependent SHG. The realization of strong SHG with high degree of polarization may pave the way toward a new platform for nonlinear optical valleytronics devices based on 2D semiconductors. Enhanced SHG intensity with near‐unity polarization from inversion‐symmetry‐broken 2D TMDC atomic layers, spiral structures, and heterostructures are realized at room temperature. It is found that there is no significant effect of multilayer interlayer interaction on SHG polarization.
ISSN:0935-9648
1521-4095
DOI:10.1002/adma.201908061