3R MoS2 with Broken Inversion Symmetry: A Promising Ultrathin Nonlinear Optical Device

Jia Shi; Peng Yu; Fucai Liu; Peng He; Rui Wang; Liang Qin; Junbo Zhou; Xin Li; Jiadong Zhou; Xinyu Sui; Shuai Zhang; Yanfeng Zhang; Qing Zhang; Tze Chien Sum; Xiaohui Qiu; Zheng Liu; Xinfeng Liu

doi:10.1002/adma.201701486

3R MoS₂ with Broken Inversion Symmetry: A Promising Ultrathin Nonlinear Optical Device

Adv Mater. 2017 Aug;29(30). doi: 10.1002/adma.201701486. Epub 2017 Jun 7.

Authors

Jia Shi^{1

2}, Peng Yu³, Fucai Liu³, Peng He⁴, Rui Wang¹, Liang Qin^{1

2}, Junbo Zhou^{1

2}, Xin Li^{1

2}, Jiadong Zhou³, Xinyu Sui^{1

2}, Shuai Zhang¹, Yanfeng Zhang^{5

6}, Qing Zhang⁶, Tze Chien Sum⁷, Xiaohui Qiu¹, Zheng Liu³, Xinfeng Liu¹

Affiliations

¹ Division of Nanophotonics, CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, 100190, P. R. China.
² University of Chinese Academy of Sciences, 19 A Yuquan Rd, Shijingshan District, Beijing, 100049, P. R. China.
³ School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.
⁴ State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, P. R. China.
⁵ Center for Nanochemistry (CNC), Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, P. R. China.
⁶ Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing, 100871, P. R. China.
⁷ Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 637371, Singapore.

PMID: 28590583
DOI: 10.1002/adma.201701486

Abstract

Nonlinear 2D layered crystals provide ideal platforms for applications and fundamental studies in ultrathin nonlinear optical (NLO) devices. However, the NLO frequency conversion efficiency constrained by lattice symmetry is still limited by layer numbers of 2D crystals. In this work, 3R MoS₂ with broken inversion symmetry structure are grown and proved to be excellent NLO 2D crystals from monolayer (0.65 nm) toward bulk-like (300 nm) dimension. Thickness and wavelength-dependent second harmonic generation spectra offer the selection rules of appropriate working conditions. A model comprising of bulk nonlinear contribution and interface interaction is proposed to interpret the observed nonlinear behavior. Polarization enhancement with two petals along staggered stacking direction appears in 3R MoS₂ is first observed and the robust polarization of 3R MoS₂ crystal is caused by the retained broken inversion symmetry. The results provide a new arena for realizing ultrathin NLO devices for 2D layered materials.

Keywords: broken inversion symmetry; nonlinear optical (NLO) devices; polarization; second harmonic generation (SHG).