Illuminating Invisible Grain Boundaries in Coalesced Single-Orientation WS2Monolayer Films

Danielle Reifsnyder Hickey, Nadire Nayir, Mikhail Chubarov, Tanushree H. Choudhury, Saiphaneendra Bachu, Leixin Miao, Yuanxi Wang, Chenhao Qian, Vincent H. Crespi, Joan M. Redwing, Adri C.T. Van Duin, Nasim Alem

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Engineering atomic-scale defects is crucial for realizing wafer-scale, single-crystalline transition metal dichalcogenide monolayers for electronic devices. However, connecting atomic-scale defects to larger morphologies poses a significant challenge. Using electron microscopy and ReaxFF reactive force field-based molecular dynamics simulations, we provide insights into WS2 crystal growth mechanisms, providing a direct link between synthetic conditions and microstructure. Dark-field TEM imaging of coalesced monolayer WS2 films illuminates defect arrays that atomic-resolution STEM imaging identifies as translational grain boundaries. Electron diffraction and high-resolution imaging reveal that the films have nearly a single orientation with imperfectly stitched domains that tilt out-of-plane when released from the substrate. Imaging and ReaxFF simulations uncover two types of translational mismatch, and we discuss their origin related to relatively fast growth rates. Statistical analysis of >1300 facets demonstrates that microstructural features are constructed from nanometer-scale building blocks, describing the system across sub-Ångstrom to multimicrometer length scales.

Original languageEnglish (US)
Pages (from-to)6487-6495
Number of pages9
JournalNano letters
Issue number15
StatePublished - Aug 11 2021

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering


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