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{{Short description|Electronic device}}
[[File:SET schematic2.jpg|thumb|Schematic of a basic SET and its internal electrical components]]
A '''single-electron transistor''' ('''SET''') is a sensitive electronic device based on the [[Coulomb blockade]] effect. In this device the electrons flow through a [[tunnel junction]] between source/drain to a [[quantum dot]] (conductive island). Moreover, the electrical potential of the island can be tuned by a third electrode, known as the gate, which is capacitively coupled to the island. The conductive island is sandwiched between two tunnel junctions<ref>{{cite journal|last1=Mahapatra|first1=S.|last2=Vaish|first2=V.|last3=Wasshuber|first3=C.|last4=Banerjee|first4=K.|last5=Ionescu|first5=A.M.|title=Analytical Modeling of Single Electron Transistor for Hybrid CMOS-SET Analog IC Design|journal=IEEE Transactions on Electron Devices|volume=51|issue=11|year=2004|pages=1772–1782|issn=0018-9383|doi=10.1109/TED.2004.837369|bibcode=2004ITED...51.1772M|s2cid=15373278}}</ref> modeled by capacitors, <math>C_{\rm D}</math> and <math>C_{\rm S}</math>, and resistors, <math>R_{\rm D}</math> and <math>R_{\rm S}</math>, in parallel.
== History ==
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[[File:Single electron transistor.svg|thumb|right|Left to right: energy levels of source, island and drain in a single-electron transistor for the blocking state (upper part) and transmitting state (lower part).]]
The SET has, like the [[field-effect transistor|FET]], three electrodes: source, drain, and a gate. The main technological difference between the transistor types is in the channel concept. While the channel changes from insulated to conductive with applied gate voltage in the FET, the SET is always insulated. The source and drain are coupled through two
The current, <math>I,</math> from source to drain follows [[Ohm's law]] when <math>V_{\rm SD}</math> is applied, and it equals <math>\tfrac{V_{\rm SD}}{R},</math> where the main contribution of the resistance, <math>R,</math> comes from the tunnelling effects when electrons move from source to QD, and from QD to drain. <math>V_{\rm G}</math> regulates the resistance of the QD, which regulates the current. This is the exact same behaviour as in regular FETs. However, when moving away from the macroscopic scale, the quantum effects will affect the current, <math>I.</math>
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