Jun 12 2009
As electronic devices get smaller and the methods for small-scale manufacturing advance, scientists at Colorado State University are working to perfect even smaller structures by manipulating individual atoms.
A new study from Colorado State University graduate student Byungsoo Kim and associate professor of mathematics Vakhtang Putkaradze reveals that scientists can extract and replace a single atom. Collaborating on the research is Professor Takashi Hikihara from the Department of Electrical Engineering at Kyoto University in Japan.
By using the tip of an atomic force microscope - a device that resembles a long needle that probes atoms - researchers were able to show that an atom could be extracted from a lattice structure without damaging surrounding atoms. Further, the extracted atom could be deposited back into the hole that was created or where a neighboring atom once was located.
"This is like putting nails in the wall and taking them out, only the nails are atoms, the wall is lattice of atoms and the tool is the tip of atomic force microscope," said Putkaradze. "This tool is billions of billions times larger than the nails. It is a bit like doing home improvement projects with a tool that is much larger than the house. We know that this tool can deposit the atoms in the lattice, so the force between the atom and the lattice must be stronger than the force between the tool and the atom."
"On the other hand, we also know that with the same tool we can extract the atoms from the lattice, so the force between the atom and the tool must be stronger than the atom and the lattice," Putkaradze said.
This puzzle was resolved by CSU-Kyoto team. "We showed that you can both take atoms out of the lattice and put them back," Putkaradze said. "This atomic construction is much easier on some levels than 'regular' construction because of atomic vibrations; the atoms will go in and get out all by themselves, with no force necessary, just by keeping the hammer close enough and long enough to the nail and you can either take the nail out or put it in."
"The impact of this research could result in smaller, faster and more energy efficient electrical devices, such as, computers and cell phones," said Putkaradze. "There is the potential that current computers or cell phones could be 100 times faster as a result of smaller transistors and microchips. The devices would also be more energy efficient in the process."
The extraction and deposition of single atoms using the atomic force microscope tip is also a promising technique for building nanostructures. Nanotechnology is the science of creating electronic circuits and devices that are designed and built from single atoms and molecules on a scale of nanometers. One nanometer is one billionth of one meter; the size of one human hair is about 1,000 nanometers.
The study was published in the May 29, 2009, edition of Physical Review Letters.