Scientists forge ahead with electron microscopy to build quantum materials atom by atom

phys.org | 10/10/2018 | Staff
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A novel technique that nudges single atoms to switch places within an atomically thin material could bring scientists another step closer to realizing theoretical physicist Richard Feynman's vision of building tiny machines from the atom up.

A significant push to develop materials that harness the quantum nature of atoms is driving the need for methods to build atomically precise electronics and sensors. Fabricating nanoscale devices atom by atom requires delicacy and precision, which has been demonstrated by a microscopy team at the Department of Energy's Oak Ridge National Laboratory.

Transmission - Electron - Microscope - STEM - Lab

They used a scanning transmission electron microscope, or STEM, at the lab's Center for Nanophase Materials Sciences to introduce silicon atoms into a single-atom-thick sheet of graphene. As the electron beam scans across the material, its energy slightly disrupts the graphene's molecular structure and creates room for a nearby silicon atom to swap places with a carbon atom.

"We observed an electron beam-assisted chemical reaction induced at a single atom and chemical bond level, and each step has been captured by the microscope, which is rare," said ORNL's Ondrej Dyck, co-author of a study published in the journal Small that details the STEM demonstration.

Process - Scientists - Silicon - Atoms - Clusters

Using this process, the scientists were further able to bring two, three and four silicon atoms together to build clusters and make them rotate within the graphene layer. Graphene is a two-dimensional, or 2-D, layer of carbon atoms that exhibits unprecedented strength and high electrical conductivity. Dyck said he selected graphene for this work, because "it is robust against a 60-kilovolt electron beam."

"We can look at graphene for long periods of time without hurting the sample, compared with other 2-D materials such as transition metal dichalcogenide monolayers, which tend to fall apart more easily under the electron beam," he added.

STEM - Years - Tool - Manipulating

STEM has emerged in recent years as a viable tool for manipulating...
(Excerpt) Read more at: phys.org
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