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›› 2017, Vol. 34 ›› Issue (1): 8-14.DOI: 10.7523/j.issn.2095-6134.2017.01.002

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Effects of strain on mechanical and electronic properties of SnSe and SnS auxetic materials

FANG Wuzhang1, ZHANG Lichuan2, YAN Qingbo2, ZHENG Qingrong1, SU Gang1   

  1. 1 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China;
    2 College of Materials Science and Opto-Electronic Technology, University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2016-04-08 Revised:2016-05-05 Online:2017-01-15

Abstract:

SnSe and SnS are promising thermoelectric and optoelectronic materials. By means of the first-principle calculations, we systematically calculate the mechanical properties and electronic structures of SnSe and SnS and also investigate the effects of strain on these properties. We find that these properties are anisotropic. We calculate the strain-strain curve, Young's modulus, phonon dispersion, sound velocity, and the band structures under strain. We find that SnSe and SnS are auxetic materials with negative Poisson ratio which can be used in sensor and biomedicine. When strain is applied along the Z direction from -5% to 5%, the band gap of SnSe changes from 0.7eV to 1.03eV while the band gap of SnS changes from 0.85eV to 1.41eV, which indicates that strain is an effective method for improving the conversion efficiencies of SnSe and SnS as solar cell materials.

Key words: SnSe, SnS, first-principle calculations, negative Poisson ratio, strain engineering

CLC Number: