A single-atom transistor is a device that can open and close an

electrical circuit An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sour ...

by the controlled and reversible repositioning of one single

atom Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons. Every solid, liquid, gas ...

. The single-atom transistor was invented and first demonstrated in 2002 by Dr. Fangqing Xie in Prof. Thomas Schimmel's Group at the

Karlsruhe Institute of Technology The Karlsruhe Institute of Technology (KIT; german: Karlsruher Institut für Technologie) is a public research university in Karlsruhe, Germany. The institute is a national research center of the Helmholtz Association. KIT was created in 2009 w ...

(former University of Karlsruhe). By means of a small electrical voltage applied to a control

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials ...

, the so-called ''gate electrode'', a single silver atom is reversibly moved in and out of a tiny junction, in this way closing and opening an electrical contact. Therefore, the single-atom transistor works as an atomic

switch In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type ...

or atomic

relay A relay Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off A relay is an electrically operated swit ...

, where the switchable atom opens and closes the gap between two tiny electrodes called ''source'' and ''drain''. The single-atom transistor opens perspectives for the development of future atomic-scale logics and quantum electronics. At the same time, the device of the Karlsruhe team of researchers marks the lower limit of

miniaturization Miniaturization ( Br.Eng.: ''Miniaturisation'') is the trend to manufacture ever smaller mechanical, optical and electronic products and devices. Examples include miniaturization of mobile phones, computers and vehicle engine downsizing. In e ...

, as feature sizes smaller than one atom cannot be produced lithographically. The device represents a quantum transistor, the conductance of the source-drain channel being defined by the rules of

quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, q ...

. It can be operated at room temperature and at ambient conditions, i.e. neither cooling nor vacuum are required. Few atom transistors have been developed at

Waseda University , mottoeng = Independence of scholarship , established = 21 October 1882 , type = Private , endowment = , president = Aiji Tanaka , city = Shinjuku , state = Tokyo , country = Japan , students = 47,959 , undergrad = 39,382 , postgrad ...

and at Italian CNR by Takahiro Shinada and Enrico Prati, who observed the Anderson–Mott transition in miniature by employing arrays of only two, four and six individually implanted As or P atoms.

References

{{Reflist

External links

* Beilstein TV Video of the Schimmel group
The single-atom transistor – perspectives for quantum electronics at room temperature
(link offline) Transistors Condensed matter physics

See also

References

External links