single electron transistor abbr., SET (rus. транзистор, одноэлектронный) — three-electrode tunnelling device that consists of a conductive island with low self-capacitance connected to source and drain electrodes by low-capacitance and low conductance tunnel junctions and having a capacitive coupling with the gate electrode.

Description

In such a three-electrode element, if the tunnel junctions have low capacitance e2/(2C)>>kBT, C=Ctrans.1+Ctrans.2+Cgate, C - the island’s total capacitance, Ctrans. - the transition capacitance, Cgate - the gate capacitance, T - the temperature, e - the electron charge) and the conductivity (Gc<< G0=e2/hGcGc – the junction tunnelling conductance, G0 - the quantum unit of conductance), a correlated tunnel transport of electrons through the system can be implemented, and the intensity of that process (i.e., the tunnelling current) depends much on the central island charge, which includes the charge induced by the gate electric field, which enables current control throughout the element. This dependence is due to the periodic (with the period equal to U0=e/Cgate (Cgate - the mutual gate and island capacitance) dependence of the tunnelling current on the gate voltage (i.e., the induced charge). The current controllability through the system by means of the electric field of the gate underpinned the term transistor in reference to such a system, similar to the insulated-gate field-effect transistor.

The sensitivity of the system to the island charge is extremely high: it is possible to record the changes in the induced charge at the level of 10–6 of the electron charge e, at present the sensitivity of 10–5 e has been achieved. This enabled the development of single-electron transistor devices that manipulate single electrons, making it possible to build brand new computer elements with single electrons serving as a data media.


*) Coulomb blockade is the effect of blocking the electron tunnelling through the tunnel junction (or a tunnel system), due to the repulsion of the electrons in the electrode by the Coulomb field of the electron that was the last to pass the junction. Quantitatively, this effect is characterised by the size of the area with zero tunnelling conductance at the origin of the junction current-voltage characteristic (I-V curve). That area is called the Coulomb blockade voltage, critical voltage, threshold voltage, or just the Coulomb blockade.

Illustrations

Schematic representation of a single-electron transistor.
Schematic representation of a single-electron transistor.

Authors

  • Razumovsky Alexey S.
  • Soldatov Eugene S.

Sources

  1. Coulomb blockade// Wikipedia, the free encyclopedia. — http://en.wikipedia.org/wiki/Coulomb_blockade (reference date: 12.10.2009).
  2. A based on graphene single-electron transistor prototype has been created (in Russian) // CNews. — http://rnd.cnews.ru/tech/news/top/index_science.shtml?2008/04/21/297996 (reference date: 12.10.2009).

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