KIT unveils single-atom transistor

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A team of researchers, led by physicist Professor Thomas Schimmel, at the Karlsruhe Institute of Technology (KIT) have developed a single-atom transistor, the smallest transistor worldwide.

This quantum electronics component switches electrical current by controlled repositioning of a single atom, now also in the solid state in a gel electrolyte. The transistor works at room temperature and consumes very little energy, opening up a range of new opportunities in terms of information technology.

Information technology presently has a share of more than 10% in total power consumption and the transistor is the central element of digital data processing in computing centres, PCs, smartphones, or in embedded systems for many applications from the washing machine to the airplane.

In future, the single-atom transistor developed by the team at KIT might considerably enhance energy efficiency in information technology.

“This quantum electronics element enables switching energies smaller than those of conventional silicon technologies by a factor of 10,000,” said Schimmel, a physicist and nanotechnology expert, 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 was appointed Co-Director of the Center for Single-Atom Electronics and Photonics established jointly by KIT and ETH Zurich.

The scientists have produced two minute metallic contacts. Between them, there is a gap as wide as a single metal atom.

“By an electric control pulse, we position a single silver atom into this gap and close the circuit,” explained Professor Schimmel. “When the silver atom is removed again, the circuit is interrupted.”

The 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 at room temperature.

The single-atom transistor is based on an entirely new technical approach. The transistor exclusively consists of metal, no semiconductors are used. This results in extremely low electric voltages and, hence, an extremely low energy consumption. So far, KIT’s single-atom transistor has applied a liquid electrolyte. Now, Schimmel and his team have designed a transistor that works in 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.