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Title: Evolution of Metastable Defects and Its Effect on the Electronic Properties of MoS 2 Films

Here, we report on structural and electronic properties of defects in chemical vapor-deposited monolayer and few-layer MoS 2 films. Scanning tunneling microscopy, Kelvin probe force microscopy, and transmission electron microscopy were used to obtain high resolution images and quantitative measurements of the local density of states, work function and nature of defects in MoS 2 films. We track the evolution of defects that are formed under heating and electron beam irradiation. We observe formation of metastable domains with different work function values after annealing the material in ultra-high vacuum to moderate temperatures. We attribute these metastable values of the work function to evolution of crystal defects forming during the annealing. The experiments show that sulfur vacancies formed after exposure to elevated temperatures diffuse, coalesce, and migrate bringing the system from a metastable to equilibrium ground state. The process could be thermally or e-beam activated with estimated energy barrier for sulfur vacancy migration of 0.6 eV in single unit cell MoS 2. Even at equilibrium conditions, the work function and local density of states values are strongly affected near grain boundaries and edges. The results provide initial estimates of the thermal budgets available for reliable fabrication of MoS 2-based integrated electronicsmore » and indicate the importance of defect control and layer passivation.« less
Authors:
 [1] ;  [2] ; ORCiD logo [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [4] ;  [4] ; ORCiD logo [2]
  1. Drexel Univ., Philadelphia, PA (United States); Slovak Academy of Sciences, Bratislava (Slovak Republic)
  2. Drexel Univ., Philadelphia, PA (United States)
  3. Temple Univ., Philadelphia, PA (United States); Brookhaven National Lab. (BNL), Upton, NY (United States)
  4. Temple Univ., Philadelphia, PA (United States)
  5. Temple Univ., Philadelphia, PA (United States); Institute for Physics of Microstructure RAS, Novgorod (Russia)
  6. Temple Univ., Philadelphia, PA (United States); Univ. of Salerno, Fisciano (SA) (Italy)
  7. Temple Univ., Philadelphia, PA (United States); Univ. of San Francisco, San Francisco, CA (United States)
  8. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-205792-2018-JAAM
Journal ID: ISSN 2045-2322
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1456903