Out-of-plane Piezoelectricity and Ferroelectricity in Layered α-In2Se3 Nano-flakes

Yu Zhou, Di Wu, Yihan Zhu, Yujin Cho, Qing He, Xiao Yang, Kevin Herrera, Zhaodong Chu, Yu Han, Mike Downer, Hailin Peng, Keji Lai

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564 Scopus citations


Piezoelectric and ferroelectric properties in the two dimensional (2D) limit are highly desired for nanoelectronic, electromechanical, and optoelectronic applications. Here we report the first experimental evidence of out-of-plane piezoelectricity and ferroelectricity in van der Waals layered α-In2Se3 nano-flakes. The non-centrosymmetric R3m symmetry of the α-In2Se3 samples is confirmed by scanning transmission electron microscopy, second-harmonic generation, and Raman spectroscopy measurements. Domains with opposite polarizations are visualized by piezo-response force microscopy. Single-point poling experiments suggest that the polarization is potentially switchable for α-In2Se3 nano-flakes with thicknesses down to ~ 10 nm. The piezotronic effect is demonstrated in two-terminal devices, where the Schottky barrier can be modulated by the strain-induced piezopotential. Our work on polar α-In2Se3, one of the model 2D piezoelectrics and ferroelectrics with simple crystal structures, shows its great potential in electronic and photonic applications.
Original languageEnglish (US)
Pages (from-to)5508-5513
Number of pages6
JournalNano Letters
Issue number9
StatePublished - Aug 30 2017


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