Managing Crystals' Growth Process

At this point, the foundation of the electronics industry lies directly on semiconductors, materials that provide computers with the substrate they need to achieve their full performances. Many semiconductors, in turn, are built out of thin films, which need to be grown in the lab. Researchers at the Cornell University, in Ithaca, New York, announce the development of a new method of managing how the crystalline structures are grown, by harnessing the random darting motions of the atomic particles that determine how the crystals grow. The work was supported by the US National Science Foundation (NSF).

“The main benefit of smooth crystalline films in electronic devices is that electrons can travel from one place to another in a device with minimal disruption. This in turn leads to faster electronics and lower electricity consumption,” the NSF Division of Materials Research Program Director, Charles Ying, explains. Details of the amazing proposal were published in the January 22 online issue of the esteemed journal Science. Additional funding came from the Cornell Center for Materials Research, which is also supported through NSF grants.

What the CU researchers basically did was model the layer-by-layer growth of crystals. Instead of atoms, they used particles larger and easier to observe, but still small enough to behave like atoms. They used a solution containing plastic spheres, each 50 times smaller than the width of a human hair, to model the growth process in its most intimate details. The team then analyzed how the crystal structure assembled itself layer by layer, using optical microscopes. In addition to observing the growth process in unprecedented details, the team was also able to manipulate single “atoms” and determine which type of configuration was best suited to promoting a smooth crystal growth.

The group discovered what it called “random darting motions” in the fake atoms, which it determined to play an important part in how the larger crystals developed. “If the principles we have uncovered can be applied to the atomic scale, scientists will be able to better control the growth of thin films used to manufacture electronic components for our computers and cell phones,” CU Assistant Professor of Physics Itai Cohen, who has been the leader of the investigation, says.

The paper's authors are former postdoctoral associate Rajesh Ganapathy, now a faculty member at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore, India, as well as Sharon Gerbode and Mark Buckley, graduate students in the Cohen lab at CU. In addition to NSF, the work was funded by the King Abdullah University of Science and Technology and the Cornell Nanoscale Science and Technology Facility.



Video: Using a solution of tiny plastic spheres 50 times smaller than a human hair, scientists at Cornell University discovered the thin, smooth crystalline sheets needed to make semiconductors could be grown more smoothly by managing the random darting motions of the atomic particles that affected how the crystals grew.

Credit: John Savage / Rajesh Ganapathy / Itai Cohen