The device developed by Professor Thomas Schimmel and his team at the Institute of Applied Physics (APH) switches electrical current by controlled repositioning of a single atom in a gel electrolyte. The single-atom transistor works at room temperature and consumes very little energy, opening up entirely new perspectives for information technology says the team.
"This quantum electronics element enables switching energies smaller than those of conventional silicon technologies by a factor of 10,000," said Prof Schimmel, who conducts research at the APH, the Institute of Nanotechnology (INT), and the Material Research Center for Energy Systems (MZE) of KIT. Earlier this year, Professor Schimmel, who is considered the pioneer of single-atom electronics, was appointed Co-Director of the Center for Single-Atom Electronics and Photonics established jointly by KIT and ETH Zurich.
The scientists produced two minute metallic contacts with a gap as wide as a single metal atom that was tested with source–drain currents ranging from 1 to 8 µA. "By an electric control pulse, we position a single silver atom into this gap and close the circuit," said Schimmel. "When the silver atom is removed again, the circuit is interrupted."
The world's smallest transistor switches current through the controlled reversible movement of a single atom. Contrary to conventional quantum electronics components, the single-atom transistor does not only work at extremely low temperatures near absolute zero, i.e. -273°C, but already at room temperature. This is a big advantage for future applications.
The single-atom transistor also consists of metal with no semiconductors are used. This results in extremely low electric voltages and, hence, an extremely low energy consumption. Previous devices developed at KIT have used has applied a liquid electrolyte, but the new version uses a solid electrolyte.
The gel electrolyte produced by gelling an aqueous silver electrolyte with pyrogenic silicon dioxide combines the advantages of a solid with the electrochemical properties of a liquid. In this way, both safety and handling of the single-atom transistor are improved.