Cho Chullhee, Zhang Zhichao, Kim Jin Myung, Ma Peiwen J, Haque Md Farhadul, Snapp Peter, Nam SungWoo
Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States.
Cryogenics and Fluids Branch, NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, United States.
Nano Lett. 2023 Oct 25;23(20):9340-9346. doi: 10.1021/acs.nanolett.3c02550. Epub 2023 Oct 5.
To date, controlled deformation of two-dimensional (2D) materials has been extensively demonstrated with substrate-supported structures. However, interfacial effects arising from these supporting materials may suppress or alter the unique behavior of the deformed 2D materials. To address interfacial effects, we report, for the first time, the formation of a micrometer-scale freestanding wrinkled structure of 2D material without any encapsulation layers where we observed the enhanced light-matter interactions with a spatial modulation. Freestanding wrinkled monolayer WSe exhibited about a 330% enhancement relative to supported wrinkled WSe quantified through photoinduced force microscopy. Spatial modulation and enhancement of light interaction in the freestanding wrinkled structures are attributed to the enhanced strain-gradient effect (i.e., out-of-plane polarization) enabled by removing the constraining support and proximate dielectrics. Our findings offer an additional degree of freedom to modulate the out-of-plane polarization and enhance the out-of-plane light-matter interaction in 2D materials.
迄今为止，二维（2D）材料的可控变形已在衬底支撑结构中得到广泛证明。然而，这些支撑材料产生的界面效应可能会抑制或改变变形二维材料的独特行为。为了解决界面效应问题，我们首次报道了形成一种微米级的二维材料独立褶皱结构，该结构没有任何封装层，在此我们观察到了通过空间调制增强的光与物质相互作用。通过光致力显微镜定量分析，独立褶皱的单层WSe相对于支撑褶皱的WSe表现出约330%的增强。独立褶皱结构中光相互作用的空间调制和增强归因于通过去除约束支撑和邻近电介质实现的增强应变梯度效应（即面外极化）。我们的研究结果为调制二维材料中的面外极化和增强面外光与物质相互作用提供了额外的自由度。
