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Breaking Inversion Symmetry in 2D Semiconductors by Built-In Electric Fields across the van der Waals
Chuansheng Xia1, Xinyu Yang2, Qiannan Cui3
1State Key Laboratory of Digital Medical Engineering, School of Biological Science and Medical Engineering, Southeast University, Nanjing 211189, China.
Abstract:
As important building blocks of integrated optoelectronic chips, most multilayer and bulk 2D layered semiconductors undertake out-of-plane inversion symmetry, which limits their multifunctional applications. Here, we propose a facile interfacial engineering means of breaking such inversion symmetry by built-in electric fields across the semiconductor-metal van der Waals heterointerface. Broken inversion symmetry of 2H WS2 layers has been experimentally confirmed by strong second harmonic generation (SHG) in fabricated bulk WS2/Au heterostructures. Through correlated SHG, atomic force, and surface potential mapping measurements and density function theory simulation (DFT), we unambiguously confirm the proposed physical mechanism. These results provide more possibilities of utilizing a 2D semiconductor/metal heterostructure to construct multifunctional integrated optoelectronic chips.
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