Electron microscopy carves 3D nanostructures

Researchers have used electron microscopy to develop a unique way to build 3-D structures as small as one to two billionths of a metre.

The study by scientists at the Department of Energy’s Oak Ridge National Laboratory (ORNL) published an account of their work in the journal Small.

They show that  scanning transmission electron microscopes can be used for precision sculpting in complex oxide materials as well as imaging.

“We can make smaller things with more precise shapes,” said ORNL’s Albina Borisevich, who led the study.

“When we exposed the amorphous layer to an electron beam, we seemed to nudge it toward adopting its preferred crystalline state,” she said. “It does that exactly where the electron beam is.”

The crystal growth in perfect alignment was responsible for the control researchers could bring to bear on the structures.

“We’re using fine control of the beam to build something inside the solid itself,” said ORNL’s Stephen Jesse.

“We’re making transformations that are buried deep within the structure. It would be like tunneling inside a mountain to build a house.”

The technique provides single atomic plane precision and could be used in fabricating structures for functional nanoscale devices such as microchips.

The perfect crystalline alignment ensures that the same electrical and mechanical properties extend throughout the whole material.

The scientists happened upon the method by chance while imaging an imperfectly prepared strontium titanate thin film. The sample, consisting of a crystalline substrate covered by an amorphous layer of the same material, transformed as the electron beam passed through it.

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