Probing the uniaxial strains in MoS2 using polarized Raman spectroscopy: A first-principles study

Danna Doratotaj, Jeffrey R. Simpson, and Jia-An Yan
Phys. Rev. B 93, 075401 – Published 1 February 2016

Abstract

Characterization of strain in two-dimensional (2D) crystals is important for understanding their properties and performance. Using first-principles calculations, we study the effects of uniaxial strain on the Raman-active modes in monolayer MoS2. We show that the in-plane E mode at 384 cm1 and the out-of-plane A1 mode at 403 cm1 can serve as fingerprints for the uniaxial strain in this 2D material. Specifically, under a uniaxial strain, the doubly degenerate E mode splits into two nondegenerate modes: one is the E mode in which atoms vibrate in parallel to the strain direction, and the other is the E mode in which atoms vibrate perpendicular to the strain direction. The frequency of the E mode blueshifts for a compressive strain, but redshifts for a tensile strain. In addition, due to the strain-induced anisotropy in the MoS2 lattice, the polarized Raman spectra of the E and E modes exhibit distinct angular dependence for specific laser polarization setups, allowing for a precise determination of the direction of the uniaxial strain with respect to the crystallographic orientation. Furthermore, we find that the polarized Raman intensity of the A1 mode also shows evident dependence on the applied strain, providing additional effective clues for determining the direction of the strain even without knowledge of the crystallographic orientation. Thus, polarized Raman spectroscopy offers an efficient nondestructive way to characterize the uniaxial strains in monolayer MoS2.

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  • Received 4 November 2015
  • Revised 8 January 2016

DOI:https://doi.org/10.1103/PhysRevB.93.075401

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Danna Doratotaj, Jeffrey R. Simpson, and Jia-An Yan*

  • Department of Physics, Astronomy, and Geosciences, Towson University, 8000 York Road, Towson, Maryland 21252, USA

  • *jiaanyan@gmail.com

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Issue

Vol. 93, Iss. 7 — 15 February 2016

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