Editing Diode (section)

{{Short description|Two-terminal electronic component}}
{{Other uses}}
{{Infobox electronic component
| name              = Diode
| image             = Diode-closeup.jpg
| caption           = Close-up view of a [[silicon]] diode. The anode is on the right side; the cathode is on the left side (where it is marked with a black band). The square [[Crystalline silicon|silicon crystal]] can be seen between the two [[Lead (electronics)|leads]].
| type              = Active
| inventor          = [[Jagadish Chandra Bose]]
| invention_Year    = 1901
| pins              = [[Anode]] and [[cathode]]
| symbol            = [[File:Diode symbol.svg|150px]]
}}

[[File:Dioden.JPG|thumb|Various semiconductor diodes. Left: A four-diode [[bridge rectifier]]. Next to it is a [[1N4148 signal diode]]. On the far right is a [[Zener diode]]. In most diodes, a white or black painted band identifies the [[cathode]] into which electrons will flow when the diode is conducting. Electron flow is the reverse of [[conventional current]] flow.<ref>{{cite book|url=https://books.google.com/books?id=NunPn6R__TAC&pg=PA81|title=Electronic Circuits: Fundamentals and Applications, 3rd Ed.|last=Tooley|first=Mike|publisher=Routledge|year=2013|isbn=978-1-136-40731-4|page=81}}</ref><ref name="Crecraft">{{cite book | last = Crecraft | first = Filip Mincic |author2=Stephen Gergely | title = Analog Electronics: Circuits, Systems and Signal Processing | publisher = Butterworth-Heinemann | year = 2002 | page = 110 | url = https://books.google.com/books?id=lS7qN6iHyBYC&pg=PA110 | isbn = 0-7506-5095-8}}</ref><ref name="Horowitz">{{cite book | last = Horowitz | first = Paul | author2=Winfield Hill | title = The Art of Electronics, 2nd Ed. | publisher = Cambridge University Press | year = 1989 | location = London | page = 44 | url = https://books.google.com/books?id=bkOMDgwFA28C&pg=PA44 | isbn = 0-521-37095-7}}</ref>]]

A '''diode''' is a two-[[Terminal (electronics)|terminal]] [[electronic component]] that conducts [[electric current]] primarily in [[One-way traffic|one direction]] (asymmetric [[electrical conductance|conductance]]). It has low (ideally zero) [[Electrical resistance and conductance|resistance]] in one direction and high (ideally infinite) resistance in the other.

A [[semiconductor]] diode, the most commonly used type today, is a [[Crystallinity|crystalline]] piece of semiconductor material with a [[p–n junction]] connected to two electrical terminals.<ref>{{cite web|url=https://www.element14.com/community/docs/DOC-22519/l/physical-explanation-general-semiconductors |title=Physical Explanation – General Semiconductors |date=2010-05-25 |access-date=2010-08-06}}</ref> It has an [[Exponential function|exponential]] [[current–voltage characteristic]]. Semiconductor diodes were the first [[Semiconductor device|semiconductor electronic devices]]. The discovery of asymmetric electrical conduction across the contact between a [[Crystal|crystalline]] mineral and a metal was made by German physicist [[Ferdinand Braun]] in 1874. Today, most diodes are made of [[silicon]], but other semiconducting materials such as [[gallium arsenide]] and [[germanium]] are also used.<ref>{{cite web |url=http://www.element-14.com/community/docs/DOC-22518/l/the-constituents-of-semiconductor-components |archive-url=https://web.archive.org/web/20110710183421/http://www.element14.com/community/docs/DOC-22518/l/the-constituents-of-semiconductor-components |archive-date=2011-07-10 |title=The Constituents of Semiconductor Components |date=2010-05-25 |access-date=2010-08-06}}</ref>

The obsolete '''thermionic diode''' is a [[vacuum tube]] with two [[electrode]]s, a heated [[cathode]] and a [[plate electrode|plate]], in which [[Electron|electrons]] can flow in only one direction, from the cathode to the plate.

Among many uses, diodes are found in [[rectifier]]s to convert [[alternating current]] (AC) power to [[direct current]] (DC), [[demodulation]] in [[radio receiver]]s, and can even be used for [[Boolean Logic|logic]] or as [[temperature sensor]]s. A common variant of a diode is a [[light-emitting diode]], which is used as [[electric lighting]] and status indicators on electronic devices.