Growing up with the twist

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Science  02 Apr 2021:
Vol. 372, Issue 6537, pp. 44-45
DOI: 10.1126/science.372.6537.44-d

Twisted layers of two-dimensional materials can display a variety of electron-correlation effects, but their fabrication usually requires exfoliation, transfer, and alignment of the sheets. Yu et al. show that twisted grain boundaries can form when monolayer crystals of molybdenum disulfide grown with random orientations by chemical vapor deposition on a silica surface collide and coalesce. Electron microscopy and Raman and second-harmonic generation spectroscopy showed that misorientations at the shared grain boundary >20° were preserved and led to moiré twist angles between 20° and 55°. Bilayers with dimensions from 2 to 10 micrometers formed from the top layer climbing over the bottom layer and aligning with it through kink nucleation and propagation.

ACS Nano 15, 4504 (2021).

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