Saturday, May 27, 2023

Advancing atomic-scale manufacturing

Graphene appeared impervious to the electron beam.

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Graphene is of great scientific interest due to its variety of unique properties. Nanopatterning and atomic scale modifications of graphene are expected to enable further control over its intrinsic properties, providing ways to tune the electronic properties through geometric and strain effects, introduce edge states and other local or extended topological defects, and sculpt circuit paths.

The focused beam of a scanning transmission electron microscope (STEM) can remove atoms, enabling milling, doping, and deposition. Utilization of STEM as an atomic-scale fabrication platform is increasing; however, a detailed understanding of beam-induced processes and the subsequent cascade of aftereffects is lacking.

Scientists at Oak Ridge National Laboratory discovered when they automated the beam of an electron microscope to precisely drill holes in the atomically thin lattice of graphene, the drilled holes closed up.

Ondrej Dyck, who co-led the study with Stephen Jesse at ORNL’s Center for Nanophase Materials Sciences, said, “Graphene appeared impervious to the electron beam.”

Jesse said, “It heals locally, like the (fictitious) liquid-metal T-1000 in Terminator 2: Judgment Day.”

On the lab’s Summit supercomputer, theory-based calculations were used to explain why the quasi-metal may heal: When heated graphene is present, single atomic vacancies move quickly through it until they collide with other vacancies and become immobilised.

Dyck said, “Similar processes are likely to extend to other 2D materials.”

Jesse said“Controlling such processes could help us realize graphene’s promise for quantum information science.”

Journal Reference:

  1. Ondrej Dyck et al. The role of temperature on defect diffusion and nanoscale patterning in graphene. Carbon. DOI: 10.1016/j.carbon.2022.09.006
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