Strain dependence of band gaps and exciton energies in pure and mixed transition-metal dichalcogenides

Rodrick Kuate Defo, Shiang Fang, Sharmila N. Shirodkar, Georgios A. Tritsaris, Athanasios Dimoulas, and Efthimios Kaxiras
Phys. Rev. B 94, 155310 – Published 27 October 2016

Abstract

The ability to fabricate 2D device architectures with desired properties, based on stacking of weakly (van der Waals) interacting atomically thin layers, is quickly becoming reality. In order to design ever more complex devices of this type, it is crucial to know the precise strain and composition dependence of the layers' electronic and optical properties. Here, we present a theoretical study of these dependences for monolayers with compositions varying from pure MX2 to the mixed MXY, where M=Mo, W and X,Y=S, Se. We employ both density-functional-theory and GW calculations, as well as values of the exciton binding energies based on a self-consistent treatment of dielectric properties, to obtain the band gaps that correspond to optical or transport measurements; we find reasonable agreement with reported experimental values for the unstrained monolayers. Our predictions for the strain-dependent electronic properties should be a useful guide in the effort to design heterostructures composed of these layers on various substrates.

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  • Received 6 June 2016
  • Revised 30 August 2016

DOI:https://doi.org/10.1103/PhysRevB.94.155310

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Rodrick Kuate Defo1, Shiang Fang1, Sharmila N. Shirodkar2, Georgios A. Tritsaris2, Athanasios Dimoulas3, and Efthimios Kaxiras1,2

  • 1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
  • 2John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
  • 3Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, 15310, Aghia Paraskevi, Athens, Greece

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Issue

Vol. 94, Iss. 15 — 15 October 2016

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