Atomic transistor

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An atomic transistor , also known as a single atom transistor , is an electrical component with which an electrical circuit can be opened and closed in a similar way to a relay . This is made possible by the controlled and reversible repositioning of a single atom or molecule .

Conventional transistors are used on the one hand as amplifiers , on the other hand they are the switches that represent 0 and 1 in computers. Single atom transistors are only transistors in the second sense. In some implementations, they do not carry the digital information but that of a qubit .

Different variants of single atom transistors

Polypyridine suspension

In 2002, Paul McEuen's research group at Cornell University realized a single-atom transistor in which a cobalt atom was suspended in a poly- pyridine molecule between two gold electrodes. The cobalt atom can be controlled between the charge states Co 2+ and Co 3+ by means of the gate voltage .

Graph

In 2004, Kostya Novoselov and Andre Geim from Manchester University succeeded in building transistors by applying a graphene layer on silicon . The transistor was one atomic layer thick and on the order of a few atoms. Kostya Novoselov and Andre Geim received the 2010 Nobel Prize in Physics for their work on graphs .

Silver atom in electrolyte solution

Structure of the atomic transistor

The prototypes , which have been manufactured by the Karlsruhe Institute of Technology since 2004, consist of gold electrodes attached to a carrier material such as B. glass or silicon were applied. By applying a small electrical voltage to a control electrode, the so-called gate electrode, a single silver atom is reversibly moved to and from a tiny contact point, so that an electrical contact closes and opens. In this way, the single atom transistor functions as an atomic switch or atomic relay, with the switchable atom opening and closing the gap between two tiny electrodes, source and drain.

There is a distance of 50 to 100 nm between the connections  . For production, silver is deposited on the two electrodes until contact is made by a silver atom. This atom is aligned so that it can move between two stable positions so that the contact is either fully open or closed. With the help of the voltage between the source and gate connections , the position of the silver atom can be controlled in such a way that the load circuit between the drain and source electrodes opens or closes.

At the same time, the component from the Karlsruhe research team marks the lower limit of miniaturization, since structure sizes that are smaller than an atom cannot be produced. The component is a quantum transistor, the conductance of the source-drain channel is determined by the laws of quantum mechanics. It can be operated at room temperature and under real ambient conditions, i.e. neither cooling nor vacuum are required.

Phosphorus doping of silicon surfaces

In 2011, a cooperation between Australian, South Korean, US and German scientists succeeded in building a transistor on the surface of silicon . The surface was doped with phosphorus for both the electrodes and the actual transistor . As a result, the switching atom is fixed at a lattice point on the silicon (approx. 1 nm), while in the previous experimental setups, spatial inaccuracies of approx. 10 nm had to be accepted.

Uses and Benefits

  • Atomic transistors are switched by a few atoms, which means that the switching times are significantly shorter than with conventional transistors and that they can be used in high-frequency technology .
  • Switching an atomic transistor is possible at voltages of a few millivolts. As a result, the power consumption of these electronic components is very low.
  • Because only a few atoms or molecules are used for switching, there can only be two switching states, “permeable” and “impermeable”. Compared to continuously switchable, semiconductor-based transistors, this is an advantage in the construction of quantum components and quantum computers .

Individual evidence

  1. ↑ David Brand: Cornell scientists create single-atom transistor by implanting molecule between wires, enabling 'virtual dance of electrons'. Cornell News Service, June 12, 2002, accessed December 2, 2012 .
  2. ↑ Jiwoong Park et al .: Coulomb blockade and the Kondo effect in single-atom transistors . In: Nature . tape 417 , 2002, pp. 722-725 , doi : 10.1038 / nature00791 ( PDF on Paul McEuen's website [accessed December 2, 2012]).
  3. ^ David Manners: Manchester University makes single atom graphene transistor. (No longer available online.) ElectronicsWeekly.com, April 18, 2008, formerly original ; Retrieved December 2, 2012 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Dead Link / www.electronicsweekly.com  
  4. ^ KS Novoselov, AK Geim et al .: Electric Field Effect in Atomically Thin Carbon Films . In: Science . tape 306 , 2004, pp. 666–669 ( PDF on Manchester University website [accessed December 2, 2012]).
  5. ^ Paul Rincon: Materials breakthrough wins Nobel. BBC News, October 5, 2010, accessed December 2, 2012 .
  6. ↑ Fang-Qing Xie, Christian Obermair, Thomas Schimmel: Switching an electrical current with atoms: the reproducible operation of a multi-atom relay . In: Solid State Communications . tape 132 , no. 7 , November 2004, p. 437-442 , doi : 10.1016 / j.ssc.2004.08.024 .
  7. ↑ F.-Q. Xie et al. a .: Independently Switchable Atomic Quantum Transistors by Reversible Contact Reconstruction . In: Nano Lett. tape 8 , no. 12 , 2008, p. 4493-4497 , doi : 10.1021 / nl802438c .
  8. ^ C. Obermair, FQ Xie, T. Schimmel: The Single-Atom Transistor: perspectives for quantum electronics on the atomic-scale . In: Europhysics News . tape 41 , no. 4 , 2010, p. 25-28 ( PDF ).
  9. ↑ Fangqing Xie, Robert Maul, Christian Obermair, Wolfgang Wenzel, Gerd Schön, Thomas Schimmel: Multilevel Atomic ‐ Scale Transistors Based on Metallic Quantum Point Contacts . In: Advanced Materials . tape 22 , no. 18 , May 11, 2010, pp. 2033-2036 , doi : 10.1002 / adma.200902953 .
  10. ↑ F.-Q. Xie, L. Nittler, Ch. Obermair, Th. Schimmel: Gate-Controlled Atomic Quantum Switch . In: Physical Review Letters . tape 93 , no. 12 , 2004, p. 128303 , doi : 10.1103 / PhysRevLett.93.128303 ( [1] ).
  11. ^ Thomas Schimmel, Christian Obermair, Fangqing Xie: Atomare Electronics . Switching electrical currents with individual atoms. In: Nanotechnology . No. December 6 , 2005 ( PDF ).
  12. ↑ Th. Schimmel: The single-atom transistor. (Video) perspectives for quantum electronics at room temperature. Beilstein-TV, April 11, 2012, accessed on January 1, 2013 (English).
  13. ↑ Martin Fuechsle u. a .: A single-atom transistor . In: Nature Nanotechnology . tape 7 , no. 4 , 2012, p. 242–246 , doi : 10.1038 / nnano.2012.21 .