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Enhanced Shift Currents in Monolayer 2D GeS and SnS by Strain-Induced Band Gap Engineering

Authors
  • Kaner, Ngeywo Tolbert1
  • Wei, Yadong1
  • Jiang, Yingjie1
  • Li, Weiqi1
  • Xu, Xiaodong1
  • Pang, Kaijuan1
  • Li, Xingji1
  • Yang, Jianqun1
  • Jiang, YongYuan1
  • Zhang, Guiling2
  • Tian, Wei Quan3
  • 1 Harbin Institute of Technology, China , (China)
  • 2 Harbin University of Science and Technology, China , (China)
  • 3 Chongqing University, China , (China)
Type
Published Article
Journal
ACS Omega
Publisher
American Chemical Society (ACS)
Publication Date
Jul 09, 2020
Volume
5
Issue
28
Pages
17207–17214
Identifiers
DOI: 10.1021/acsomega.0c01319
PMID: 32715206
PMCID: PMC7376894
Source
PubMed Central
License
Unknown

Abstract

Group IV monochalcogenides exhibit spontaneous polarization and ferroelectricity, which are important in photovoltaic materials. Since strain engineering plays an important role in ferroelectricity, in the present work, the effect of equibiaxial strain on the band structure and shift currents in monolayer two-dimensional (2D) GeS and SnS has systematically been investigated using the first-principles calculations. The conduction bands of those materials are more responsive to strain than the valence bands. Increased equibiaxial compressive strain leads to a drastic reduction in the band gap and finally the occurrence of phase transition from semiconductor to metal at strains of −15 and −14% for GeS and SnS, respectively. On the other hand, tensile equibiaxial strain increases the band gap slightly. Similarly, increased equibiaxial compressive strain leads to a steady almost four times increase in the shift currents at a strain of −12% with direction change occurring at −8% strain. However, at phase transition from semiconductor to metal, the shift currents of the two materials completely vanish. Equibiaxial tensile strain also leads to increased shift currents. For SnS, shift currents do not change direction, just as the case of GeS at low strain; however, at a strain of +8% and beyond, direction reversal of shift currents beyond the band gap in GeS occur.

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