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Narrow-gap physical vapour deposition synthesis of ultrathin SnS1-xSex (0≤x≤1) two-dimensional alloys with unique polarized Raman spectra and high (opto)electronic properties

Abstract

Here we report ultrathin SnS1-xSex alloyed nanosheets synthesized via a narrow-gap physical vapor deposition approach. The SnS1-xSex alloy presents a uniform quadrangle shape with a lateral size of 5-80 μm and a thickness of several nanometers. Clear orthorhombic symmetries and unique in-plane anisotropic properties of the 2D alloyed nanosheets were found with the help of x-ray diffraction, high resolution transmission electron microscopy and polarized Raman spectroscopy. Moreover, the 2D alloyed field-effect transistors were fabricated, exhibiting a unipolar p-type semiconductor behavior. This study also provided a lesson that thickness of the alloyed channels played the major role in the current on/off ratio, and the high ratio of 2.10×102 measured from large ultrathin SnS1-xSex device was two orders of magnitude larger than that of previously reported SnS, SnSe nanosheets based transistors because of the capacitance shielding effect. Obviously Enhanced Raman peaks were also found in the thinner nanosheets. Furthermore, the ultrathin SnS0.5Se0.5 based photodetector showed a highest responsivity of 1.69 A·W-1 and a short response time of 40 ms under illumination of 532 nm laser from 405-808 nm. Simultaneously, the corresponding highest external quantum efficiency of 392 % and detectivity of 3.96×104 Jones were also achieved. Hopefully, the narrow-gap synthesis technique provides us an improved strategy to obtain large ultrathin 2D nanosheets which may tend to grow into thicker ones for stronger interlayer Van der Waals forces, and the enhanced physical and (opto)electrical performances in the obtained ultrathin SnS1-xSex alloyed nanosheets prove its great potential in the future applications for versatile devices.

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Publication details

The article was received on 30 Jan 2018, accepted on 02 Apr 2018 and first published on 09 Apr 2018


Article type: Paper
DOI: 10.1039/C8NR00856F
Citation: Nanoscale, 2018, Accepted Manuscript
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    Narrow-gap physical vapour deposition synthesis of ultrathin SnS1-xSex (0≤x≤1) two-dimensional alloys with unique polarized Raman spectra and high (opto)electronic properties

    W. Gao, Y. Li, J. Guo, M. Ni, M. Liao, H. Mo and J. Li, Nanoscale, 2018, Accepted Manuscript , DOI: 10.1039/C8NR00856F

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