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Title: Probing the Optical Properties and Strain-Tuning of Ultrathin Mo 1–xW xTe 2

Ultrathin transition metal dichalcogenides (TMDCs) have recently been extensively investigated to understand their electronic and optical properties. Here we study ultrathin Mo 0.91W 0.09Te 2, a semiconducting alloy of MoTe 2, using Raman, photoluminescence (PL), and optical absorption spectroscopy. Mo 0.91W 0.09Te 2 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 MoTe 2 counterpart. We apply tensile strain, for the first time, to monolayer MoTe 2 and Mo 0.91W 0.09Te 2 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 MoTe 2 and Mo 0.91W 0.09Te 2 extend the range of band gaps of TMDC monolayers further into the near-infrared, an important attribute for potential applications in optoelectronics.
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)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; W911NF-15-1-0570; 70NANB16H043; FA9550-14-1-0040; FA9550-14-1-0251; 1542883
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 18; Journal Issue: 4; Journal ID: ISSN 1530-6984
American Chemical Society
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; alloyed 2D materials; band gap; MoTe2; MoWTe2; photoluminescence; strain engineering
OSTI Identifier: