Materials Science

Implanted Atoms as Implements

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Science  19 Apr 2013:
Vol. 340, Issue 6130, pp. 250-251
DOI: 10.1126/science.340.6130.250-d

Ion implantation can be used to remove a thin layer of a crystal. For example, in the fabrication of silicon-on-insulator chips, a layer of hetero atoms that can form a gas (e.g., hydrogen atoms) are implanted as a subsurface layer. Upon heating, the formation of the gas dislodges the thin film from the bulk crystal. Cun et al. examined such effects at the level of a single monolayer; in this case, a boron nitride (BN) overlayer grown on the (111) surface of rhodium that forms a “nanomesh” superstructure of wires and holes with a lattice constant of 3.2 nm. After implantation of low-energy argon ions, scanning tunneling microscopy revealed protrusions along the wires created by subsurface argon atoms trapped at two different sites. These structures were stable in air, but annealing to 900 K caused a “can-opener” effect; that is, the formation of well-defined 2-nm holes in the perturbed overlayer along with the corresponding removed flakes of BN. Similar effects were seen with neon ions and for graphene layers on ruthenium surfaces.

CREDIT: H. CUN ET AL., NANO LETT. (10.1021/NL40449Y 2013)

Nano Lett. 10.1021/nl400449y (2013).

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