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Title: Probing the Optical Properties and Strain-Tuning of Ultrathin Mo1–xWxTe2

Journal Article · · Nano Letters
ORCiD logo [1];  [2];  [2];  [2];  [3];  [4]; ORCiD logo [4];  [4]; ORCiD logo [2]; ORCiD logo [1]
  1. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Stanford Univ., Stanford, CA (United States)
  3. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Theiss Research, La Jolla, CA (United States)
  4. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)

Ultrathin transition metal dichalcogenides (TMDCs) have recently been extensively investigated to understand their electronic and optical properties. Here we study ultrathin Mo0.91W0.09Te2, a semiconducting alloy of MoTe2, using Raman, photoluminescence (PL), and optical absorption spectroscopy. Mo0.91W0.09Te2 transitions from an indirect to a direct optical band gap in the limit of monolayer thickness, exhibiting an optical gap of 1.10 eV, very close to its MoTe2 counterpart. We apply tensile strain, for the first time, to monolayer MoTe2 and Mo0.91W0.09Te2 to tune the band structure of these materials; we observe that their optical band gaps decrease by 70 meV at 2.3% uniaxial strain. The spectral widths of the PL peaks decrease with increasing strain, which we attribute to weaker exciton–phonon intervalley scattering. Furthermore, strained MoTe2 and Mo0.91W0.09Te2 extend the range of band gaps of TMDC monolayers further into the near-infrared, an important attribute for potential applications in optoelectronics.

Research Organization:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC02-76SF00515; W911NF-15-1-0570; 70NANB16H043; FA9550-14-1-0040; FA9550-14-1-0251; 1542883
OSTI ID:
1457055
Journal Information:
Nano Letters, Vol. 18, Issue 4; ISSN 1530-6984
Publisher:
American Chemical SocietyCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 42 works
Citation information provided by
Web of Science

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Strain dependence of photoluminescence and circular dichroism in transition metal dichalcogenides: a k · p analysis journal January 2018
Research Update: Recent progress on 2D materials beyond graphene: From ripples, defects, intercalation, and valley dynamics to straintronics and power dissipation journal August 2018
Misfit Strain-Induced Buckling for Transition-Metal Dichalcogenide Lateral Heterostructures: A Molecular Dynamics Study journal August 2018
Strain engineering in functional 2-dimensional materials journal February 2019
Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides text January 2019