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New Nanowires Are Just a Few Atoms Thick

Sub-nanometre channels embedded in two-dimensional materials.

A slight mismatch between the hexagonal structures of molybdenum disulfide and tungsten diselenide creates a strain that can be released by the formation of a "5|7 dislocation," in which two hexagons collapse to form a pentagon and a heptagon. Reactions with molybdenum disulfide in the environment cause the dislocation to move deeper into the tungsten diselenide, drawing a nanowire of molybdenum disulfide behind it.

April 15, 2018 | Source: Massachusetts Institute of Technology, news.mit.edu, 4 Dec 2017, Larry Hardesty

“Two-dimensional materials” — materials deposited in layers that are only a few atoms thick — are promising for both high-performance electronics and flexible, transparent electronics that could be layered onto physical surfaces to make computing ubiquitous.

The best-known 2-D material is graphene, which is a form of carbon, but recently researchers have been investigating other 2-D materials, such as molybdenum disulfide, which have their own, distinct advantages.

Producing useful electronics, however, requires integrating multiple 2-D materials in the same plane, which is a tough challenge. In 2015, researchers at King Abdullah University in Saudi Arabia developed a technique for depositing molybdenum disulfide (MoS2) next to tungsten diselenide (WSe2), with a very clean junction between the two materials. With a variation of the technique, researchers at Cornell University then found that they could induce long, straight wires of MoS2 — only a few atoms in diameter— to extend into the WSe2,  while preserving the clean junction.