View source for Transistor

{{Short description|Solid-state electrically operated switch also used as an amplifier}}
{{Other uses}}
{{Use mdy dates|date=January 2021}}
[[File:Transistorer (cropped).jpg|thumb|Size comparison of [[bipolar junction transistor]] packages, including (from left to right): [[SOT-23]], [[TO-92]], [[TO-126]], and [[TO-3]]]]
[[File:MOSFET Structure.png|thumb|[[Metal–oxide–semiconductor field-effect transistor]] (MOSFET), showing [[Metal gate|gate]] (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (white).]]

A '''transistor''' is a [[semiconductor device]] used to [[Electronic amplifier|amplify]] or [[electronic switch|switch]] electrical signals and [[electrical power|power]]. It is one of the basic building blocks of modern [[electronics]].<ref>{{cite web |title=Transistor |website=Britannica |url=https://www.britannica.com/technology/transistor |access-date=January 12, 2021 }}</ref> It is composed of [[semiconductor material]], usually with at least three [[Terminal (electronics)|terminals]] for connection to an electronic circuit. A [[voltage]] or [[Electric current|current]] applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more in miniature form are found embedded in [[integrated circuit]]s. Because transistors are the key active components in practically all modern [[electronics]], many people consider them one of the 20th century's greatest inventions.<ref name="auto1">{{cite web |title=A History of the Invention of the Transistor and Where It Will Lead Us |url=https://massless.info/images/A%20history%20of%20the%20invention%20of%20the%20transistor%20and%20where%20it%20will%20lead%20us.pdf |website=IEEE JOURNAL OF SOLID-STATE CIRCUITS Vol 32 No 12 |date = December 1997}}</ref>

[[Physicist]] [[Julius Edgar Lilienfeld]] proposed the concept of a [[field-effect transistor]] (FET) in 1926, but it was not possible to construct a working device at that time.<ref>{{cite web |title=1926 – Field Effect Semiconductor Device Concepts Patented |website=Computer History Museum |url=http://www.computerhistory.org/siliconengine/field-effect-semiconductor-device-concepts-patented/ |access-date=March 25, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160322023120/http://www.computerhistory.org/siliconengine/field-effect-semiconductor-device-concepts-patented/ |archive-date=March 22, 2016 }}</ref> The first working device was a [[point-contact transistor]] invented in 1947 by physicists [[John Bardeen]], [[Walter Brattain]], and [[William Shockley]] at [[Bell Labs]]; the three shared the 1956 [[Nobel Prize in Physics]] for their achievement.<ref>{{cite web |title=The Nobel Prize in Physics 1956 |website=Nobelprize.org |publisher=Nobel Media AB |url=https://www.nobelprize.org/nobel_prizes/physics/laureates/1956/ |access-date=December 7, 2014 |url-status=live |archive-url=https://web.archive.org/web/20141216204332/http://www.nobelprize.org/nobel_prizes/physics/laureates/1956/ |archive-date=December 16, 2014 }}</ref> The most widely used type of transistor is the [[metal–oxide–semiconductor field-effect transistor]] (MOSFET), invented by [[Mohamed Atalla]] and [[Dawon Kahng]] at Bell Labs in 1959.<ref name="computerhistory"/><ref name="Lojek"/><ref name="computer history-transistor"/> Transistors revolutionized the field of electronics and paved the way for smaller and cheaper [[radio]]s, [[calculator]]s, [[computer]]s, and other electronic devices.

Most transistors are made from very pure [[silicon]], and some from [[germanium]], but certain other semiconductor materials are sometimes used. A transistor may have only one kind of charge carrier in a [[field-effect transistor]], or may have two kinds of charge carriers in  [[bipolar junction transistor]] devices. Compared with the [[vacuum tube]], transistors are generally smaller and require less power to operate. Certain vacuum tubes have advantages over transistors at very high operating frequencies or high operating voltages, such as [[Traveling-wave tube]]s and [[Gyrotron]]s. Many types of transistors are made to standardized specifications by multiple manufacturers.

==History==
{{Main|History of the transistor}}
[[File:Julius Edgar Lilienfeld (1881-1963).jpg|thumb|[[Julius Edgar Lilienfeld]] proposed the concept of a [[field-effect transistor]] in 1925.]]
The [[thermionic]] [[triode]], a [[vacuum tube]] invented in 1907, enabled amplified [[radio]] technology and long-distance [[telephony]]. The triode, however, was a fragile device that consumed a substantial amount of power. In 1909, [[physicist]] [[William Eccles (physicist)|William Eccles]] discovered the crystal diode oscillator.<ref>{{Cite book | url=https://books.google.com/books?id=YiJaEAUj258C&q=Eccles+Oscillator+Galena&pg=PA430 | title=Concise Encyclopedia of Building and Construction Materials| isbn=9780262132480| last1=Moavenzadeh| first1=Fred| year=1990| publisher=MIT Press}}</ref> Physicist [[Julius Edgar Lilienfeld]] filed a patent for a [[field-effect transistor]] (FET) in Canada in 1925,<ref>{{Cite book | url=https://worldwide.espacenet.com/publicationDetails/originalDocument?FT=D&date=19270719&DB=&CC=CA&NR=272437A&KC=A&locale=en_EP# | title=Specification of electric current control mechanism patent application| last1=Lilienfeld| first1=Julius Edgar| year=1927}}</ref> intended as a [[Solid-state (electronics)|solid-state]] replacement for the triode.<ref>Vardalas, John (May 2003) [http://www.todaysengineer.org/2003/May/history.asp Twists and Turns in the Development of the Transistor] {{webarchive|url=https://web.archive.org/web/20150108082709/http://www.todaysengineer.org/2003/May/history.asp |date=January 8, 2015 }} ''IEEE-USA Today's Engineer''.</ref><ref name="auto">Lilienfeld, Julius Edgar, "Method and apparatus for controlling electric current" {{US patent|1745175}} January 28, 1930 (filed in Canada 1925-10-22, in US October 8, 1926).</ref> He filed identical patents in the United States in 1926<ref>{{cite web|title=Method And Apparatus For Controlling Electric Currents|publisher=United States Patent and Trademark Office|url=http://www.google.com/patents?id=uBFMAAAAEBAJ&printsec=abstract#v=onepage&q&f=false}}</ref> and 1928.<ref>{{cite web|title=Amplifier For Electric Currents|publisher=United States Patent and Trademark Office| url=http://www.google.com/patents?id=jvhAAAAAEBAJ&printsec=abstract#v=onepage&q&f=false}}</ref><ref>{{cite web| title=Device For Controlling Electric Current|publisher=United States Patent and Trademark Office| url=http://www.google.com/patents?id=52BQAAAAEBAJ&printsec=abstract#v=onepage&q&f=false}}</ref> However, he did not publish any research articles about his devices nor did his patents cite any specific examples of a working prototype. Because the production of high-quality [[semiconductor]] materials was still decades away, Lilienfeld's solid-state amplifier ideas would not have found practical use in the 1920s and 1930s, even if such a device had been built.<ref name="todaysengineer.org">{{cite web|title=Twists and Turns in the Development of the Transistor|publisher=Institute of Electrical and Electronics Engineers, Inc.|url=http://www.todaysengineer.org/2003/May/history.asp|url-status=dead|archive-url=https://web.archive.org/web/20150108082709/http://www.todaysengineer.org/2003/May/history.asp|archive-date=January 8, 2015}}</ref> In 1934, inventor [[Oskar Heil]] patented a similar device in Europe.<ref>[http://v3.espacenet.com/publicationDetails/biblio?CC=GB&NR=439457&KC=&FT=E Heil, Oskar, "Improvements in or relating to electrical amplifiers and other control arrangements and devices"], Patent No. GB439457, European Patent Office, filed in Great Britain 1934-03-02, published December 6, 1935 (originally filed in Germany March 2, 1934).</ref>

===Bipolar transistors===
{{See|Point-contact transistor|Bipolar junction transistor}}
[[File:Bardeen Shockley Brattain 1948.JPG|thumb|[[John Bardeen]], [[William Shockley]], and [[Walter Brattain]] at [[Bell Labs]] in 1948; Bardeen and Brattain invented the [[point-contact transistor]] in 1947 and Shockley invented the [[bipolar junction transistor]] in 1948.]]
[[File:Replica-of-first-transistor.jpg|thumb|A replica of the first working transistor, a [[point-contact transistor]] invented in 1947]]
[[File:Herbert F. Mataré 1950.png|thumb|[[Herbert Mataré]] (pictured in 1950) independently invented a point-contact transistor in June 1948.]]
[[File: Philco Surface Barrier transistor=1953.jpg|thumb|A Philco surface-barrier transistor developed and produced in 1953]]
From November 17 to December 23, 1947, [[John Bardeen]] and [[Walter Brattain]] at [[AT&T Corporation|AT&T]]'s [[Bell Labs]] in [[Murray Hill, New Jersey]], performed experiments and observed that when two gold point contacts were applied to a crystal of [[germanium]], a signal was produced with the output power greater than the input.<ref>{{cite web| title=November 17 – December 23, 1947: Invention of the First Transistor| publisher=American Physical Society| url=http://www.aps.org/publications/apsnews/200011/history.cfm| url-status=live| archive-url=https://web.archive.org/web/20130120065607/http://www.aps.org/publications/apsnews/200011/history.cfm| archive-date=January 20, 2013| df=mdy-all}}</ref> Solid State Physics Group leader [[William Shockley]] saw the potential in this, and over the next few months worked to greatly expand the knowledge of [[Semiconductor|semiconductors]]. The term ''transistor'' was coined by [[John R. Pierce]] as a contraction of the term ''[[transresistance]]''.<ref>{{cite book|editor=Millman, S. |title=A History of Engineering and Science in the Bell System, Physical Science (1925–1980)|  page=102|year=1983|publisher=AT&T Bell Laboratories}}</ref><ref>{{cite book|author=Bodanis, David |title=Electric Universe|publisher=Crown Publishers, New York|year=2005|isbn=978-0-7394-5670-5}}</ref><ref>{{cite encyclopedia|encyclopedia=American Heritage Dictionary| edition=3rd| year=1992|publisher=Houghton Mifflin| location=Boston| title=transistor}}</ref> According to [[Lillian Hoddeson]] and Vicki Daitch, Shockley proposed that Bell Labs' first patent for a transistor should be based on the field-effect and that he be named as the inventor. Having unearthed Lilienfeld's patents that went into obscurity years earlier, lawyers at Bell Labs advised against Shockley's proposal because the idea of a field-effect transistor that used an electric field as a "grid" was not new. Instead, what Bardeen, Brattain, and Shockley invented in 1947 was the first [[point-contact transistor]].<ref name="todaysengineer.org"/> To acknowledge this accomplishment, Shockley, Bardeen and Brattain jointly received the 1956 [[Nobel Prize in Physics]] "for their researches on semiconductors and their discovery of the transistor effect".<ref>{{cite web|title=The Nobel Prize in Physics 1956|url=http://nobelprize.org/nobel_prizes/physics/laureates/1956/|publisher=nobelprize.org|url-status=live|archive-url=https://web.archive.org/web/20070312091604/http://nobelprize.org/nobel_prizes/physics/laureates/1956/|archive-date=March 12, 2007}}</ref><ref name="Guarnieri 1">{{Cite journal|last=Guarnieri|first=M.|year=2017|title=Seventy Years of Getting Transistorized|journal=IEEE Industrial Electronics Magazine|volume=11|issue=4|pages=33–37|doi=10.1109/MIE.2017.2757775|s2cid=38161381|hdl=11577/3257397|hdl-access=free}}</ref>

Shockley's team initially attempted to build a field-effect transistor (FET) by trying to modulate the conductivity of a semiconductor, but was unsuccessful, mainly due to problems with the [[surface states]], the [[dangling bond]], and the [[germanium]] and [[copper]] compound materials. Trying to understand the mysterious reasons behind this failure led them instead to invent the bipolar [[point-contact transistor|point-contact]] and [[junction transistor]]s.<ref name="Lee">{{cite book |last1=Lee |first1=Thomas H. |title=The Design of CMOS Radio-Frequency Integrated Circuits |journal=Soldering & Surface Mount Technology |date=2003 |volume=16 |issue=2 |publisher=[[Cambridge University Press]] |doi=10.1108/ssmt.2004.21916bae.002 |isbn=9781139643771 |s2cid=108955928 |url=https://www.semanticscholar.org/paper/The-Design-of-CMOS-Radio-Frequency-Integrated-Ellis/c0018d231b4960f7a6c4f581b086212d7f8b0d15?p2df |archive-url=https://web.archive.org/web/20211021005313/https://www.semanticscholar.org/paper/The-Design-of-CMOS-Radio-Frequency-Integrated-Ellis/c0018d231b4960f7a6c4f581b086212d7f8b0d15?p2df |archive-date=2021-10-21 }}</ref><ref name="Puers">{{cite book |last1=Puers |first1=Robert |last2=Baldi |first2=Livio |last3=Voorde |first3=Marcel Van de |last4=Nooten |first4=Sebastiaan E. van |title=Nanoelectronics: Materials, Devices, Applications, 2 Volumes |date=2017 |publisher=[[John Wiley & Sons]] |isbn=9783527340538 |page=14 |url=https://books.google.com/books?id=JOqVDgAAQBAJ&pg=PA14}}</ref>

In 1948, the point-contact transistor was independently invented by physicists [[Herbert Mataré]] and [[Heinrich Welker]] while working at the ''[[Compagnie des Freins et Signaux Westinghouse]]'', a [[Westinghouse Electric (1886)|Westinghouse]] subsidiary in [[Paris]]. Mataré had previous experience in developing [[Cat's-whisker detector|crystal rectifiers]] from [[silicon]] and germanium in the German [[radar]] effort during [[World War II]]. With this knowledge, he began researching the phenomenon of "interference" in 1947. By June 1948, witnessing currents flowing through point-contacts, he produced consistent results using samples of germanium produced by Welker, similar to what Bardeen and Brattain had accomplished earlier in December 1947. Realizing that Bell Labs' scientists had already invented the transistor, the company rushed to get its "transistron" into production for amplified use in France's telephone network, filing his first transistor patent application on August 13, 1948.<ref>{{Patent|FR|1010427|H. F. Mataré / H. Welker / Westinghouse: "Nouveau sytème crystallin à plusieur électrodes réalisant des relais de effects électroniques" filed on August 13, 1948}}</ref><ref>{{patent|US|2673948|H. F. Mataré / H. Welker / Westinghouse, "Crystal device for controlling electric currents by means of a solid semiconductor" French priority August 13, 1948}}</ref><ref>{{cite web|title=1948, The European Transistor Invention|publisher=Computer History Museum|url=http://www.computerhistory.org/semiconductor/timeline/1948-European.html|url-status=live|archive-url=https://web.archive.org/web/20120929202704/http://www.computerhistory.org/semiconductor/timeline/1948-European.html|archive-date=September 29, 2012}}</ref>

The first [[bipolar junction transistor]]s were invented by Bell Labs' William Shockley, who applied for patent (2,569,347) on June 26, 1948. On April 12, 1950, Bell Labs chemists [[Gordon Teal]] and [[Morgan Sparks]] successfully produced a working bipolar NPN junction amplifying germanium transistor. Bell announced the discovery of this new "sandwich" transistor in a press release on July 4, 1951.<ref>{{Cite web|url=https://www.computerhistory.org/siliconengine/first-grown-junction-transistors-fabricated/|archiveurl=https://web.archive.org/web/20170404035446/http://www.computerhistory.org/siliconengine/first-grown-junction-transistors-fabricated/|url-status=live|title=1951: First Grown-Junction Transistors Fabricated &#124; The Silicon Engine &#124; Computer History Museum|archivedate=April 4, 2017|website=www.computerhistory.org}}</ref><ref>{{cite web |url=https://www.pbs.org/transistor/science/info/junctw.html |title=A Working Junction Transistor |website=[[PBS]] |access-date=September 17, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170703002246/http://www.pbs.org/transistor/science/info/junctw.html |archive-date=July 3, 2017 }}</ref>

The first high-frequency transistor was the [[surface-barrier transistor|surface-barrier germanium transistor]] developed by [[Philco]] in 1953, capable of operating at frequencies up to {{nowrap|60 MHz}}.<ref>{{cite journal| journal=Proceedings of the IRE| date=December 1953| author=Bradley, W.E. |title=The Surface-Barrier Transistor: Part I-Principles of the Surface-Barrier Transistor| volume=41| issue=12| pages=1702–1706| doi=10.1109/JRPROC.1953.274351| s2cid=51652314}}</ref> They were made by etching depressions into an n-type germanium base from both sides with jets of [[Indium(III) sulfate]] until it was a few ten-thousandths of an inch thick. [[Indium]] electroplated into the depressions formed the collector and emitter.<ref>''The Wall Street Journal'', December 4, 1953, page 4, Article "Philco Claims Its Transistor Outperforms Others Now In Use"</ref><ref>Electronics magazine, January 1954, Article "Electroplated Transistors Announced"</ref>

AT&T first used transistors in telecommunications equipment in the No.&nbsp;4A Toll Crossbar Switching System in 1953, for selecting trunk circuits from routing information encoded on translator cards.<ref>P. Mallery, ''Transistors and Their Circuits in the 4A Toll Crossbar Switching System'', AIEE Transactions, September 1953, p.388</ref> Its predecessor, the Western Electric No.&nbsp;3A [[phototransistor]], read the mechanical encoding from punched metal cards.

The first prototype pocket [[transistor radio]] was shown by INTERMETALL, a company founded by [[Herbert Mataré]] in 1952, at the [[Internationale Funkausstellung Berlin|''Internationale Funkausstellung Düsseldorf'']] from August 29 to September 6, 1953.<ref>1953 Foreign Commerce Weekly; Volume 49; pp.23</ref><ref>{{cite news |url=https://www.welt.de/welt_print/article2721871/Der-deutsche-Erfinder-des-Transistors.html |title=''Der deutsche Erfinder des Transistors – Nachrichten Welt Print – DIE WELT'' |publisher=Welt.de |date=November 23, 2011 |access-date=May 1, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160515182422/http://www.welt.de/welt_print/article2721871/Der-deutsche-Erfinder-des-Transistors.html |archive-date=May 15, 2016 |newspaper=Die Welt }}</ref> The first production-model pocket transistor radio was the [[Regency TR-1]], released in October 1954.<ref name="Guarnieri 1" /> Produced as a joint venture between the Regency Division of Industrial Development Engineering Associates, I.D.E.A. and [[Texas Instruments]] of Dallas, Texas, the TR-1 was manufactured in Indianapolis, Indiana. It was a near pocket-sized radio with four transistors and one germanium diode. The industrial design was outsourced to the Chicago firm of Painter, Teague and Petertil. It was initially released in one of six colours: black, ivory, mandarin red, cloud grey, mahogany and olive green. Other colours shortly followed.<ref>{{cite web |url=http://www.regencytr1.com/ |title=Regency TR-1 Transistor Radio History |access-date=April 10, 2006 |url-status=live |archive-url=https://web.archive.org/web/20041021040145/http://www.regencytr1.com/ |archive-date=October 21, 2004 }}</ref><ref>{{cite web |url=http://www.ericwrobbel.com/books/regency.htm |title=The Regency TR-1 Family |access-date=April 10, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170427155821/http://www.ericwrobbel.com/books/regency.htm |archive-date=April 27, 2017 }}</ref><ref>{{cite web |url=http://www.radiomuseum.org/dsp_hersteller_detail.cfm?company_id=3886 |title=Regency manufacturer in USA, radio technology from United St |access-date=April 10, 2017 |url-status=live |archive-url=https://web.archive.org/web/20170410214244/http://www.radiomuseum.org/dsp_hersteller_detail.cfm?company_id=3886 |archive-date=April 10, 2017 }}</ref>

The first production all-transistor car radio was developed by Chrysler and [[Philco]] corporations and was announced in the April 28, 1955, edition of ''The Wall Street Journal''. Chrysler made the Mopar model 914HR available as an option starting in fall 1955 for its new line of 1956 Chrysler and Imperial cars, which reached dealership showrooms on October 21, 1955.<ref>Wall Street Journal, "Chrysler Promises Car Radio With Transistors Instead of Tubes in '56", April 28, 1955, page 1</ref><ref>{{cite web|url=http://www.fcanorthamerica.com/company/Heritage/Pages/Chrysler-Heritage-1950.aspx|title=FCA North America - Historical Timeline 1950-1959|website=www.fcanorthamerica.com|access-date=December 5, 2017|archive-date=April 2, 2015|archive-url=https://web.archive.org/web/20150402062327/http://www.fcanorthamerica.com/company/Heritage/Pages/Chrysler-Heritage-1950.aspx|url-status=dead}}</ref>

The [[Sony]] TR-63, released in 1957, was the first mass-produced transistor radio, leading to the widespread adoption of transistor radios.<ref name="Skrabec">{{cite book | last1  = Skrabec | first1 = Quentin R. Jr. | title  = The 100 Most Significant Events in American Business: An Encyclopedia | publisher = ABC-CLIO  | date   = 2012 | pages  = 195–7 | url    = https://books.google.com/books?id=2kc69qrid9oC&pg=PA195 | isbn   = 978-0313398636 }}</ref> Seven million TR-63s were sold worldwide by the mid-1960s.<ref>{{cite news |last1=Snook |first1=Chris J. |title=The 7 Step Formula Sony Used to Get Back On Top After a Lost Decade |url=https://www.inc.com/chris-j-snook/sonys-7-step-formula-for-entrepreneurial-success-business-longevity.html |work=[[Inc. (magazine)|Inc.]] |date=November 29, 2017}}</ref> Sony's success with transistor radios led to transistors replacing vacuum tubes as the dominant [[electronic technology]] in the late 1950s.<ref>{{cite magazine |last1=Kozinsky |first1=Sieva |title=Education and the Innovator's Dilemma |url=https://www.wired.com/insights/2014/01/education-innovators-dilemma/ |magazine=[[Wired (magazine)|Wired]] |access-date=October 14, 2019 |date=January 8, 2014}}</ref>

The first working silicon transistor was developed at Bell Labs on January 26, 1954, by [[Morris Tanenbaum]].  The first production commercial silicon transistor was announced by [[Texas Instruments]] in May 1954. This was the work of [[Gordon Teal]], an expert in growing crystals of high purity, who had previously worked at Bell Labs.<ref>{{cite journal| journal=IEEE Spectrum| title=The Lost History of the Transistor|author1-link=Michael Riordan (physicist)| author=Riordan, Michael| date=May 2004| pages=48–49| url=https://spectrum.ieee.org/biomedical/devices/the-lost-history-of-the-transistor| url-status=live| archive-url=https://web.archive.org/web/20150531113132/https://spectrum.ieee.org/biomedical/devices/the-lost-history-of-the-transistor| archive-date=May 31, 2015| df=mdy-all}}</ref><ref>Chelikowski, J. (2004) "Introduction: Silicon in all its Forms", p. 1 in ''Silicon: evolution and future of a technology''. P. Siffert and E. F. Krimmel (eds.). Springer, {{ISBN|3-540-40546-1}}.</ref><ref>McFarland, Grant (2006) ''Microprocessor design: a practical guide from design planning to manufacturing''. McGraw-Hill Professional. p. 10. {{ISBN|0-07-145951-0}}.</ref>

===Field effect transistors===
{{Main|Field-effect transistor}}

The basic principle of the [[field-effect transistor]] (FET) was first proposed by physicist [[Julius Edgar Lilienfeld]] when he filed a [[patent]] for a device similar to [[MESFET]] in 1926, and for an insulated-gate field-effect transistor in 1928.<ref name="auto"/><ref>Lilienfeld, Julius Edgar, "Device for controlling electric current" {{US patent|1900018}} March 7, 1933 (filed in US March 28, 1928).</ref> The FET concept was later also theorized by engineer [[Oskar Heil]] in the 1930s and by [[William Shockley]] in the 1940s.

In 1945 [[JFET]] was patented by [[Heinrich Welker]].<ref>{{cite book |title=The Physics of Semiconductors|author=Grundmann, Marius|isbn=978-3-642-13884-3 |publisher=Springer-Verlag|year=2010}}</ref> Following Shockley's theoretical treatment on JFET in 1952, a working practical JFET was made in 1953 by [[George C. Dacey]] and [[Ian Munro Ross|Ian M. Ross]].<ref>[https://link.springer.com/chapter/10.1007%2F978-1-4684-7263-9_11#page-1 Junction Field-Effect Devices], ''Semiconductor Devices for Power Conditioning'', 1982.</ref>

In 1948, Bardeen patented the progenitor of MOSFET, an insulated-gate FET (IGFET) with an inversion layer. Bardeen's patent, and the concept of an inversion layer, forms the basis of CMOS technology today.<ref>{{cite book | author=Howard R. Duff | title=AIP Conference Proceedings | chapter=John Bardeen and transistor physics | date=2001 | volume=550 | pages=3–32 | doi=10.1063/1.1354371 | doi-access=free }}</ref>

===MOSFET (MOS transistor)===
{{Main|MOSFET}}
{{multiple image
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In the early years of the [[semiconductor industry]], companies focused on the [[junction transistor]], a relatively bulky device that was difficult to [[mass-production|mass-produce]], limiting it to several specialized applications. [[Field-effect transistor]]s (FETs) were theorized as potential alternatives, but researchers could not get them to work properly, largely due to the [[surface state]] barrier that prevented the external [[electric field]] from penetrating the material.<ref name="Moskowitz">{{cite book |last1=Moskowitz |first1=Sanford L. |title=Advanced Materials Innovation: Managing Global Technology in the 21st century |date=2016 |publisher=[[John Wiley & Sons]] |isbn=9780470508923 |page=168 |url=https://books.google.com/books?id=2STRDAAAQBAJ&pg=PA168}}</ref>

In 1957, Bell Labs engineer [[Mohamed Atalla]] proposed a new method of [[semiconductor device fabrication]]: coating a [[silicon wafer]] with an insulating layer of [[silicon oxide]] so electricity could overcome the surface state and reliably penetrate to the semiconducting silicon below. The process, known as [[surface passivation]], became critical to the [[semiconductor industry]], as it enabled the mass-production of silicon [[integrated circuit]]s.<ref name="atalla">{{cite web|title=Martin Atalla in Inventors Hall of Fame, 2009|url=https://www.invent.org/inductees/martin-john-m-atalla|access-date=June 21, 2013}}</ref><ref name="kahng">{{cite web |title=Dawon Kahng |url=https://www.invent.org/inductees/dawon-kahng |website=[[National Inventors Hall of Fame]] |access-date=June 27, 2019}}</ref><ref>{{cite book |last1=Lojek |first1=Bo |title=History of Semiconductor Engineering |url=https://archive.org/details/historysemicondu00loje_697 |url-access=limited |date=2007 |publisher=[[Springer Science & Business Media]] |isbn=9783540342588 |page=[https://archive.org/details/historysemicondu00loje_697/page/n128 120]}}</ref> Building on the method, he developed the [[metal–oxide–semiconductor]] (MOS) process,<ref name="atalla"/> and proposed that it could be used to build the first working silicon FET. 

Atalla and his Korean colleague [[Dawon Kahng]] developed the [[metal–oxide–semiconductor field-effect transistor]] (MOSFET), or ''MOS transistor'', in 1959,<ref name="atalla"/><ref name="computerhistory">{{cite journal|url=https://www.computerhistory.org/siliconengine/metal-oxide-semiconductor-mos-transistor-demonstrated/|title=1960 - Metal Oxide Semiconductor (MOS) Transistor Demonstrated|journal=The Silicon Engine|publisher=[[Computer History Museum]]}}</ref><ref name="Lojek">{{cite book |last1=Lojek |first1=Bo |title=History of Semiconductor Engineering |url=https://archive.org/details/historysemicondu00loje_697 |url-access=limited |date=2007 |publisher=[[Springer Science & Business Media]] |isbn=9783540342588 |pages=[https://archive.org/details/historysemicondu00loje_697/page/n327 321]–3}}</ref> the first transistor that could be miniaturized and mass-produced for a wide range of uses.<ref name="Moskowitz"/> In a self-aligned [[CMOS]] process, a transistor is formed wherever the gate layer (polysilicon or metal) crosses a diffusion layer.<ref name= selfAlignedCmos >{{cite book |last1=Mead |first1=Carver |last2=Conway |first2=Lynn |year=1991 |title=Introduction to VLSI systems |publisher=Addison Wesley Publishing Company |isbn=978-0-201-04358-7 |oclc=634332043 |url=https://archive.org/details/introductiontovl00mead |author-link1 = Carver Mead | author-link2 = Lynn Conway}}</ref>{{rp|p.1 (see Fig. 1.1)}} With its [[MOSFET scaling|high scalability]],<ref>{{cite journal |last1=Motoyoshi |first1=M. |title=Through-Silicon Via (TSV) |journal=Proceedings of the IEEE |date=2009 |volume=97 |issue=1 |pages=43–48 |doi=10.1109/JPROC.2008.2007462 |s2cid=29105721 |url=https://pdfs.semanticscholar.org/8a44/93b535463daa7d7317b08d8900a33b8cbaf4.pdf |archive-url=https://web.archive.org/web/20190719120523/https://pdfs.semanticscholar.org/8a44/93b535463daa7d7317b08d8900a33b8cbaf4.pdf |url-status=dead |archive-date=2019-07-19 |issn=0018-9219}}</ref> much lower power consumption, and higher density than bipolar junction transistors,<ref>{{cite news |title=Transistors Keep Moore's Law Alive |url=https://www.eetimes.com/author.asp?section_id=36&doc_id=1334068 |access-date=July 18, 2019 |work=[[EETimes]] |date=December 12, 2018}}</ref> the MOSFET made it possible to build [[Large scale integration|high-density]] integrated circuits,<ref name="computer history-transistor">{{cite web |title=Who Invented the Transistor? |url=https://www.computerhistory.org/atchm/who-invented-the-transistor/ |website=[[Computer History Museum]] |date=December 4, 2013 |access-date=July 20, 2019}}</ref> allowing the integration of more than 10,000 transistors in a single IC.<ref>{{cite journal |last1=Hittinger |first1=William C. |title=Metal-Oxide-Semiconductor Technology |journal=Scientific American |date=1973 |volume=229 |issue=2 |pages=48–59 |issn=0036-8733|jstor=24923169 |doi=10.1038/scientificamerican0873-48 |bibcode=1973SciAm.229b..48H }}</ref>

[[CMOS]] (complementary [[MOSFET|MOS]]) was invented by [[Chih-Tang Sah]] and [[Frank Wanlass]] at [[Fairchild Semiconductor]] in 1963.<ref name="computerhistory1963">{{cite web |title=1963: Complementary MOS Circuit Configuration is Invented |url=https://www.computerhistory.org/siliconengine/complementary-mos-circuit-configuration-is-invented/ |website=[[Computer History Museum]] |access-date=July 6, 2019}}</ref> The first report of a [[floating-gate MOSFET]] was made by Dawon Kahng and [[Simon Sze]] in 1967.<ref>D. Kahng and S. M. Sze, "A floating gate and its application to memory devices", ''The Bell System Technical Journal'', vol. 46, no. 4, 1967, pp. 1288–1295</ref> A [[double-gate]] MOSFET was first demonstrated in 1984 by [[Electrotechnical Laboratory]] researchers Toshihiro Sekigawa and Yutaka Hayashi.<ref>{{cite book |last1=Colinge |first1=J.P. |title=FinFETs and Other Multi-Gate Transistors |date=2008 |publisher=Springer Science & Business Media |isbn=9780387717517 |page=11 |url=https://books.google.com/books?id=t1ojkCdTGEEC&pg=PA11}}</ref><ref>{{cite journal |last1=Sekigawa |first1=Toshihiro |last2=Hayashi |first2=Yutaka |title=Calculated threshold-voltage characteristics of an XMOS transistor having an additional bottom gate |journal=Solid-State Electronics |date=August 1, 1984 |volume=27 |issue=8 |pages=827–828 |doi=10.1016/0038-1101(84)90036-4 |issn=0038-1101|bibcode=1984SSEle..27..827S }}</ref> [[FinFET]] (fin field-effect transistor), a type of 3D non-planar [[Multigate device|multi-gate]] MOSFET, originated from the research of Digh Hisamoto and his team at [[Hitachi|Hitachi Central Research Laboratory]] in 1989.<ref>{{cite web |title=IEEE Andrew S. Grove Award Recipients |url=https://www.ieee.org/about/awards/bios/grove-recipients.html |website=[[IEEE Andrew S. Grove Award]] |publisher=[[Institute of Electrical and Electronics Engineers]] |access-date=July 4, 2019}}</ref><ref>{{cite web |title=The Breakthrough Advantage for FPGAs with Tri-Gate Technology |url=https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/wp/wp-01201-fpga-tri-gate-technology.pdf |publisher=[[Intel]] |year=2014 |access-date=July 4, 2019}}</ref>

==Importance==
Because transistors are the key active components in practically all modern [[electronics]], many people consider them one of the 20th century's greatest inventions.<ref name="auto1"/>

The invention of the first transistor at Bell Labs was named an [[List of IEEE milestones|IEEE Milestone]] in 2009.<ref>{{cite web |url=http://www.ieeeghn.org/wiki/index.php/Milestones:Invention_of_the_First_Transistor_at_Bell_Telephone_Laboratories,_Inc.,_1947 |title=Milestones:Invention of the First Transistor at Bell Telephone Laboratories, Inc., 1947 |website=IEEE Global History Network |publisher=IEEE |access-date=August 3, 2011 |url-status=live |archive-url=https://web.archive.org/web/20111008193522/http://www.ieeeghn.org/wiki/index.php/Milestones:Invention_of_the_First_Transistor_at_Bell_Telephone_Laboratories,_Inc.,_1947 |archive-date=October 8, 2011 }}</ref> Other Milestones include the inventions of the [[junction transistor]] in 1948 and the MOSFET in 1959.<ref>{{cite web| url = http://ethw.org/Milestones:List_of_IEEE_Milestones| title = List of IEEE Milestones| date = December 9, 2020}}</ref>

The MOSFET is by far the most widely used transistor, in applications ranging from [[computer]]s and [[electronics]]<ref name="kahng"/> to [[communications technology]] such as [[smartphone]]s.<ref name="uspto">{{cite web |title=Remarks by Director Iancu at the 2019 International Intellectual Property Conference |url=https://www.uspto.gov/about-us/news-updates/remarks-director-iancu-2019-international-intellectual-property-conference |website=[[United States Patent and Trademark Office]] |date=June 10, 2019 |access-date=July 20, 2019}}</ref> It has been considered the most important transistor,<ref>{{cite book |last1=Ashley |first1=Kenneth L. |title=Analog Electronics with LabVIEW |date=2002 |publisher=[[Prentice Hall Professional]] |isbn=9780130470652 |page=10 |url=https://books.google.com/books?id=0qkc2f6EXnQC&pg=PA10}}</ref> possibly the most important invention in electronics,<ref>{{cite journal |last1=Thompson |first1=S. E. |last2=Chau |first2=R. S. |last3=Ghani |first3=T. |last4=Mistry |first4=K. |last5=Tyagi |first5=S. |last6=Bohr |first6=M. T. |title=In search of "Forever," continued transistor scaling one new material at a time |journal=[[IEEE Transactions on Semiconductor Manufacturing]] |date=2005 |volume=18 |issue=1 |pages=26–36 |doi=10.1109/TSM.2004.841816 |s2cid=25283342 |issn=0894-6507 |quote=In the field of electronics, the planar Si metal–oxide–semiconductor field-effect transistor (MOSFET) is perhaps the most important invention.}}</ref> and the device that enabled modern electronics.<ref>{{cite book |last1=Kubozono |first1=Yoshihiro |last2=He |first2=Xuexia |last3=Hamao |first3=Shino |last4=Uesugi |first4=Eri |last5=Shimo |first5=Yuma |last6=Mikami |first6=Takahiro |last7=Goto |first7=Hidenori |last8=Kambe |first8=Takashi |chapter=Application of Organic Semiconductors toward Transistors |title=Nanodevices for Photonics and Electronics: Advances and Applications |date=2015 |publisher=[[CRC Press]] |isbn=9789814613750 |page=355 |chapter-url=https://books.google.com/books?id=8wdCCwAAQBAJ&pg=PA355}}</ref> It has been the basis of modern [[digital electronics]] since the late 20th century, paving the way for the [[digital age]].<ref name="triumph">{{cite web |title=Triumph of the MOS Transistor |url=https://www.youtube.com/watch?v=q6fBEjf9WPw  |archive-url=https://ghostarchive.org/varchive/youtube/20211211/q6fBEjf9WPw| archive-date=2021-12-11 |url-status=live|website=[[YouTube]] |publisher=[[Computer History Museum]] |access-date=July 21, 2019 |date=August 6, 2010}}{{cbignore}}</ref> The [[US Patent and Trademark Office]] calls it a "groundbreaking invention that transformed life and culture around the world".<ref name="uspto"/> Its ability to be [[mass production|mass-produced]] by a highly automated process ([[semiconductor device fabrication]]), from relatively basic materials, allows astonishingly low per-transistor costs. MOSFETs are the most numerously produced artificial objects in history, with more than 13 sextillion manufactured by 2018.<ref>{{cite web |title=The most manufactured human artifact in history |url=https://computerhistory.org/blog/13-sextillion-counting-the-long-winding-road-to-the-most-frequently-manufactured-human-artifact-in-history/?key=13-sextillion-counting-the-long-winding-road-to-the-most-frequently-manufactured-human-artifact-in-history |website=Computer History |date = April 2, 2018|access-date=January 21, 2021}}</ref> 

Although several companies each produce over a billion individually packaged (known as ''[[Discrete transistor|discrete]]'') MOS transistors every year,<ref>[https://web.archive.org/web/20081206043949/http://www.globalsources.com/gsol/I/FET-MOSFET/a/9000000085806.htm FETs/MOSFETs: Smaller apps push up surface-mount supply]. globalsources.com (April 18, 2007)</ref> the vast majority are produced in [[integrated circuits]] (also known as ''ICs'', ''microchips,'' or simply ''chips''), along with [[diode]]s, [[resistor]]s, [[capacitor]]s and other [[electronic component]]s, to produce complete electronic circuits. A [[logic gate]] consists of up to about 20 transistors, whereas an advanced [[microprocessor]], as of 2022, may contain as many as 57 billion MOSFETs.<ref>{{cite web |title=Introducing M1 Pro and M1 Max: the most powerful chips Apple has ever built - Apple |url=https://www.apple.com/newsroom/2021/10/introducing-m1-pro-and-m1-max-the-most-powerful-chips-apple-has-ever-built/ |website=www.apple.com |access-date=20 October 2022}}</ref> Transistors are often organized into logic gates in microprocessors to perform computation.

The transistor's low cost, flexibility and reliability have made it ubiquitous. Transistorized [[mechatronics|mechatronic]] circuits have replaced [[cam timer|electromechanical devices]] in controlling appliances and machinery. It is often easier and cheaper to use a standard [[microcontroller]] and write a [[computer program]] to carry out a control function than to design an equivalent mechanical system.

==Simplified operation==
[[File: Transistor Simple Circuit Diagram with NPN Labels.svg|thumb|A simple circuit diagram showing the labels of an n–p–n bipolar transistor]]
A transistor can use a small signal applied between one pair of its terminals to control a much larger signal at another pair of terminals, a property called [[Gain (electronics)|gain]]. It can produce a stronger output signal, a voltage or current, proportional to a weaker input signal, acting as an [[amplifier]]. It can also be used as an electrically controlled [[switch]], where the amount of current is determined by other circuit elements.<ref>{{Cite book|last=Roland|first=James|url=https://books.google.com/books?id=g2qsDAAAQBAJ&q=how+do+transistors+work|title=How Transistors Work|date=August 1, 2016|publisher=Lerner Publications |isbn=978-1-5124-2146-0|language=en}}</ref>

There are two types of transistors, with slight differences in how they are used:

* A ''[[bipolar transistor|bipolar junction transistor (BJT)]]'' has terminals labeled '''base''', '''collector''' and '''emitter'''. A small current at the base terminal, flowing between the base and the emitter, can control or switch a much larger current between the collector and emitter.

* A ''[[field-effect transistor|field-effect transistor (FET)]]'' has terminals labeled '''gate''', '''source''' and '''drain.''' A voltage at the gate can control a current between source and drain.<ref name="Pulfrey">{{Cite book|last=Pulfrey|first=David L.|url=https://books.google.com/books?id=y9dYENs2SVUC&q=how+do+transistors+work|title=Understanding Modern Transistors and Diodes|date=January 28, 2010|publisher=Cambridge University Press|isbn=978-1-139-48467-1|language=en}}</ref>

The top image in this section represents a typical bipolar transistor in a circuit. A charge flows between emitter and collector terminals depending on the current in the base. Because the base and emitter connections behave like a semiconductor diode, a voltage drop develops between them. The amount of this drop, determined by the transistor's material, is referred to as ''V''<sub>BE</sub>.<ref name="Pulfrey" />

===Transistor as a switch===
[[File:Transistor as switch.svg|thumb|BJT used as an electronic switch in grounded-emitter configuration]]
Transistors are commonly used in [[digital circuit]]s as [[electronic switches]] which can be either in an "on" or "off" state, both for high-power applications such as [[switched-mode power supply|switched-mode power supplies]] and for low-power applications such as [[logic gate]]s. Important parameters for this application include the current switched, the voltage handled, and the switching speed, characterized by the [[rise time|rise and fall times]].<ref name="Pulfrey" />

In a switching circuit, the goal is to simulate, as near as possible, the ideal switch having the properties of an open circuit when off, the short circuit when on, and an instantaneous transition between the two states. Parameters are chosen such that the "off" output is limited to leakage currents too small to affect connected circuitry, the resistance of the transistor in the "on" state is too small to affect circuitry, and the transition between the two states is fast enough not to have a detrimental effect.<ref name="Pulfrey" />

In a grounded-emitter transistor circuit, such as the light-switch circuit shown, as the base voltage rises, the emitter and collector currents rise exponentially. The collector voltage drops because of reduced resistance from the collector to the emitter. If the voltage difference between the collector and emitter were zero (or near zero), the collector current would be limited only by the load resistance (light bulb) and the supply voltage. This is called ''saturation'' because the current is flowing from collector to emitter freely. When saturated, the switch is said to be ''on''.<ref>{{Cite book|last=Kaplan|first=Daniel|title=Hands-On Electronics|year=2003|isbn=978-0-511-07668-8|pages=47–54, 60–61|bibcode=2003hoe..book.....K}}</ref>

The use of bipolar transistors for switching applications requires biasing the transistor so that it operates between its cut-off region in the off-state and the saturation region (''on''). This requires sufficient base drive current. As the transistor provides current gain, it facilitates the switching of a relatively large current in the collector by a much smaller current into the base terminal. The ratio of these currents varies depending on the type of transistor, and even for a particular type, varies depending on the collector current. In the example of a light-switch circuit, as shown, the resistor is chosen to provide enough base current to ensure the transistor is saturated.<ref name="Pulfrey" /> The base resistor value is calculated from the supply voltage, transistor C-E junction voltage drop, collector current, and amplification factor beta.<ref>{{Cite web|title=Transistor Base Resistor Calculator|date=January 27, 2012 |url=https://kaizerpowerelectronics.dk/calculators/transistor-base-resistor-calculator/}}</ref>

===Transistor as an amplifier===
[[File:NPN common emitter AC.svg|thumb|An amplifier circuit, a common-emitter configuration with a voltage-divider bias circuit]]
The [[common-emitter amplifier]] is designed so that a small change in voltage (''V''<sub>in</sub>) changes the small current through the base of the transistor whose current amplification combined with the properties of the circuit means that small swings in ''V''<sub>in</sub> produce large changes in ''V''<sub>out</sub>.<ref name="Pulfrey" />

Various configurations of single transistor amplifiers are possible, with some providing current gain, some voltage gain, and some both.

From [[mobile phone]]s to [[television]]s, vast numbers of products include amplifiers for [[sound reproduction]], [[Transmitter|radio transmission]], and [[signal processing]]. The first discrete-transistor audio amplifiers barely supplied a few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved.<ref name="Pulfrey" />

Modern transistor audio amplifiers of up to a few hundred [[watt]]s are common and relatively inexpensive.

==Comparison with vacuum tubes==
Before transistors were developed, [[vacuum tube|vacuum (electron) tubes]] (or in the UK "thermionic valves" or just "valves") were the main active components in electronic equipment.

===Advantages===
The key advantages that have allowed transistors to replace vacuum tubes in most applications are
* No cathode heater (which produces the characteristic orange glow of tubes), reducing power consumption, eliminating delay as tube heaters warm up, and immune from [[cathode poisoning]] and depletion.
* Very small size and weight, reducing equipment size.
* Large numbers of extremely small transistors can be manufactured as a single [[integrated circuit]].
* Low operating voltages compatible with batteries of only a few cells.
* Circuits with greater energy efficiency are usually possible. For low-power applications (for example, voltage amplification) in particular, energy consumption can be very much less than for tubes.
* Complementary devices available, providing design flexibility including complementary-symmetry circuits, not possible with vacuum tubes.
* Very low sensitivity to mechanical shock and vibration, providing physical ruggedness and virtually eliminating shock-induced spurious signals (for example, [[microphonics]] in audio applications).
* Not susceptible to breakage of a glass envelope, leakage, outgassing, and other physical damage.

===Limitations===
Transistors may have the following limitations:

* They lack the higher [[electron mobility]] afforded by the vacuum of vacuum tubes, which is desirable for high-power, high-frequency operation&nbsp;&ndash; such as that used in some over-the-air [[television transmitter]]s and in [[travelling wave tube]]s used as amplifiers in some satellites
* Transistors and other solid-state devices are susceptible to damage from very brief electrical and thermal events, including [[electrostatic discharge]] in handling. Vacuum tubes are electrically much more rugged.
* They are sensitive to radiation and [[cosmic ray]]s (special [[radiation hardening|radiation-hardened]] chips are used for spacecraft devices).
* In audio applications, transistors lack the lower-harmonic distortion&nbsp;&ndash; the so-called [[tube sound]]&nbsp;&ndash; which is characteristic of vacuum tubes, and is preferred by some.<ref name=Veen1>{{Cite conference
 |last        = van der Veen
 |first       = M.
 |title       = Universal system and output transformer for valve amplifiers
 |book-title   = 118th AES Convention, Barcelona, Spain
 |year        = 2005
 |url         = http://www.mennovanderveen.nl/nl/download/download_3.pdf
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20091229114846/http://www.mennovanderveen.nl/nl/download/download_3.pdf
 |archive-date = December 29, 2009
|df          = mdy-all
}}</ref>

==Types==
=== Classification ===
{{more citations needed|section|date=December 2020}}
<!-- START OF THE SYMBOLS -->
{{float_begin|side=right}}
|- style="text-align:center;"
|[[File:BJT PNP symbol.svg|80px]]||PNP||[[File:JFET P-Channel Labelled.svg|80px]]||P-channel
|- style="text-align:center;"
|[[File:BJT NPN symbol.svg|80px]]||NPN||[[File:JFET N-Channel Labelled.svg|80px]]||N-channel
|- style="text-align:center;"
|BJT||||JFET||
{{float_end|caption=BJT and JFET symbols}}

{{float_begin|side=right}}
|- style="text-align:center;"
|[[File:IGFET P-Ch Enh Labelled.svg|80px]]||[[File:IGFET P-Ch Enh Labelled simplified.svg|80px]]||[[File:IGFET P-Ch Dep Labelled.svg|80px]]||P-channel
|- style="text-align:center;"
|[[File:IGFET N-Ch Enh Labelled.svg|80px]]||[[File:IGFET N-Ch Enh Labelled simplified.svg|80px]]||[[File:IGFET N-Ch Dep Labelled.svg|80px]]||N-channel
|- style="text-align:center;"
|colspan="2"|MOSFET enh||MOSFET dep||
{{float_end|caption=MOSFET symbols}}
<!-- END OF THE SYMBOLS -->
Transistors are categorized by
* Structure: [[MOSFET]] (IGFET), [[Bipolar junction transistor|BJT]], [[JFET]], [[insulated-gate bipolar transistor]] (IGBT), other types{{which|date=April 2021}}.
* Semiconductor material ([[dopant]]s): 
** The [[metalloids]]; [[germanium]] (first used in 1947) and [[silicon]] (first used in 1954)—in [[Amorphous silicon|amorphous]], [[Polycrystalline silicon|polycrystalline]] and [[Monocrystalline silicon|monocrystalline]] form.
** The compounds [[gallium arsenide]] (1966) and [[silicon carbide]] (1997).
** The [[alloy]] [[silicon-germanium]] (1989) 
** The [[allotrope of carbon]] [[Graphene#Electronics|graphene]] (research ongoing since 2004), etc. (see [[#Semiconductor material|Semiconductor material]]).
* [[Electrical polarity]] (positive and negative): [[NPN transistor|NPN]], [[PNP transistor|PNP]] (BJTs), N-channel, P-channel (FETs).
* Maximum [[power rating]]: low, medium, high.
* Maximum operating frequency: low, medium, high, [[radio frequency|radio]] (RF), [[microwave]] frequency (the maximum effective frequency of a transistor in a common-emitter or common-source circuit is denoted by the term {{math|''f''<sub>''T''</sub>}}, an abbreviation for [[gain–bandwidth product#Transistors|transition frequency]]—the frequency at which the transistor yields unity voltage gain)
* Application: switch, general purpose, audio, [[high voltage]], super-beta, matched pair.
* Physical packaging: [[through-hole technology|through-hole]] metal, through-hole plastic, [[Surface-mount technology|surface mount]], [[ball grid array]], power modules (see [[#Packaging|Packaging]]).
* Amplification factor [[Transistor models|{{math|''h''<sub>''FE''</sub>}}]], {{math|''β''<sub>''F''</sub>}} ([[transistor beta]])<ref>{{cite web|title=Transistor Example|url=http://www.bcae1.com/transres.htm|url-status=live|archive-url=https://web.archive.org/web/20080208150020/http://www.bcae1.com/transres.htm|archive-date=February 8, 2008}} 071003 bcae1.com</ref> or {{math|''g''<sub>''m''</sub>}} ([[transconductance]]).
* Working temperature: Extreme temperature transistors and traditional temperature transistors ({{convert|−55|to|150|C|F}}). Extreme temperature transistors include high-temperature transistors (above {{convert|150|C|F}}) and low-temperature transistors (below {{convert|-55|C|F}}). The high-temperature transistors that operate thermally stable up to {{convert|250|C|F}} can be developed by a general strategy of blending interpenetrating semi-crystalline conjugated polymers and high glass-transition temperature insulating polymers.<ref>{{Cite journal|last1=Gumyusenge|first1=Aristide|last2=Tran|first2=Dung T.|last3=Luo|first3=Xuyi|last4=Pitch|first4=Gregory M.|last5=Zhao|first5=Yan|last6=Jenkins|first6=Kaelon A.|last7=Dunn|first7=Tim J.|last8=Ayzner|first8=Alexander L.|last9=Savoie|first9=Brett M.|last10=Mei|first10=Jianguo|date=December 7, 2018|title=Semiconducting polymer blends that exhibit stable charge transport at high temperatures|journal=Science|language=en|volume=362|issue=6419|pages=1131–1134|doi=10.1126/science.aau0759|pmid=30523104|issn=0036-8075|bibcode=2018Sci...362.1131G|doi-access=free}}</ref>

Hence, a particular transistor may be described as ''silicon, surface-mount, BJT, NPN, low-power, high-frequency switch''.

=== Mnemonics ===
Convenient [[mnemonic]] to remember the type of transistor (represented by an [[electrical symbol]]) involves the direction of the arrow. For the [[Bipolar junction transistor|BJT]], on an '''n-p-n''' transistor symbol, the arrow will "'''N'''ot '''P'''oint i'''N"'''. On a '''p-n-p''' transistor symbol, the arrow "'''P'''oints i'''N''' '''P'''roudly". However, this does not apply to MOSFET-based transistor symbols as the arrow is typically reversed (i.e. the arrow for the n-p-n points inside).

===Field-effect transistor (FET)===
{{Main|Field-effect transistor}}
{{See also|JFET}}
[[File:Threshold formation nowatermark.gif|thumb|right|Operation of an [[FET]] and its {{mvar|I<sub>d</sub>}}-{{mvar|V<sub>g</sub>}} curve. At first, when no gate voltage is applied, there are no inversion electrons in the channel, so the device is turned off. As gate voltage increases, the inversion electron density in the channel increases, the current increases, and the device turns on.]]
The ''[[field-effect transistor]]'', sometimes called a ''unipolar transistor'', uses either electrons (in ''n-channel FET'') or holes (in ''p-channel FET'') for conduction. The four terminals of the FET are named ''source'', ''gate'', ''drain'', and ''body'' (''substrate''). On most FETs, the body is connected to the source inside the package, and this will be assumed for the following description.

In a FET, the drain-to-source current flows via a conducting channel that connects the ''source'' region to the ''drain'' region. The conductivity is varied by the electric field that is produced when a voltage is applied between the gate and source terminals, hence the current flowing between the drain and source is controlled by the voltage applied between the gate and source. As the gate–source voltage ({{mvar|V<sub>GS</sub>}}) is increased, the drain–source current ({{mvar|I<sub>DS</sub>}}) increases exponentially for {{mvar|V<sub>GS</sub>}} below threshold, and then at a roughly quadratic rate:  ({{math|''I<sub>DS</sub>'' ∝  (''V<sub>GS</sub>'' − ''V<sub>T</sub>'')<sup>2</sup>}}, where {{mvar|V<sub>T</sub>}} is the threshold voltage at which drain current begins)<ref name=horowitz-hill>{{cite book|last=Horowitz|first=Paul|author-link=Paul Horowitz|author2=Winfield Hill |title=The Art of Electronics|edition=2nd|year=1989|publisher=Cambridge University Press|isbn=978-0-521-37095-0|page=[115]|title-link=The Art of Electronics|author2-link=Winfield Hill}}</ref> in the "[[space charge|space-charge-limited]]" region above threshold. A quadratic behavior is not observed in modern devices, for example, at the [[65 nanometer|65 nm]] technology node.<ref name=Sansen>
{{cite book|author=Sansen, W. M. C. |title=Analog design essentials|year= 2006|page=§0152, p. 28|publisher=Springer|location=New York, Berlin|isbn=978-0-387-25746-4}}</ref>

For low noise at narrow [[bandwidth (signal processing)|bandwidth]], the higher input resistance of the FET is advantageous.

FETs are divided into two families: ''junction FET'' ([[JFET]]) and ''insulated gate FET'' (IGFET). The IGFET is more commonly known as a ''metal–oxide–semiconductor FET'' ([[MOSFET]]), reflecting its original construction from layers of metal (the gate), oxide (the insulation), and semiconductor. Unlike IGFETs, the JFET gate forms a [[p–n diode]] with the channel which lies between the source and drains. Functionally, this makes the n-channel JFET the solid-state equivalent of the vacuum tube [[triode]] which, similarly, forms a diode between its [[Control grid|grid]] and [[cathode]]. Also, both devices operate in the ''depletion-mode'', they both have a high input impedance, and they both conduct current under the control of an input voltage.

Metal–semiconductor FETs ([[MESFET]]s) are JFETs in which the [[Reverse-biased|reverse biased]] p–n junction is replaced by a [[metal–semiconductor junction]]. These, and the HEMTs (high-electron-mobility transistors, or HFETs), in which a two-dimensional electron gas with very high carrier mobility is used for charge transport, are especially suitable for use at very high frequencies (several GHz).

FETs are further divided into ''depletion-mode'' and ''enhancement-mode'' types, depending on whether the channel is turned on or off with zero gate-to-source voltage. For enhancement mode, the channel is off at zero bias, and a gate potential can "enhance" the conduction. For the depletion mode, the channel is on at zero bias, and a gate potential (of the opposite polarity) can "deplete" the channel, reducing conduction. For either mode, a more positive gate voltage corresponds to a higher current for n-channel devices and a lower current for p-channel devices. Nearly all JFETs are depletion-mode because the diode junctions would forward bias and conduct if they were enhancement-mode devices, while most IGFETs are enhancement-mode types.

====Metal–oxide–semiconductor FET (MOSFET)====
{{Main|MOSFET}}
The metal–oxide–semiconductor field-effect transistor ([[MOSFET]], MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS),<ref name="computer history-transistor"/> is a type of field-effect transistor that is [[Semiconductor device fabrication|fabricated]] by the [[thermal oxidation|controlled oxidation]] of a semiconductor, typically [[silicon]]. It has an insulated [[Metal gate|gate]], whose voltage determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic [[signal (electrical engineering)|signals]]. The MOSFET is by far the most common transistor, and the basic building block of most modern [[electronics]].<ref name="triumph"/> The MOSFET accounts for 99.9% of all transistors in the world.<ref name="computerhistory2018">{{cite web |title=13 Sextillion & Counting: The Long & Winding Road to the Most Frequently Manufactured Human Artifact in History |url=https://www.computerhistory.org/atchm/13-sextillion-counting-the-long-winding-road-to-the-most-frequently-manufactured-human-artifact-in-history/ |date=April 2, 2018 |website=[[Computer History Museum]] |access-date=July 28, 2019}}</ref>

===Bipolar junction transistor (BJT)===
{{Main|Bipolar junction transistor}}
Bipolar transistors are so named because they conduct by using both majority and minority [[charge carrier|carriers]]. The bipolar junction transistor, the first type of transistor to be mass-produced, is a combination of two junction diodes and is formed of either a thin layer of p-type semiconductor sandwiched between two n-type semiconductors (an n–p–n transistor), or a thin layer of n-type semiconductor sandwiched between two p-type semiconductors (a p–n–p transistor). This construction produces two [[p–n junction]]s: a base-emitter junction and a base-collector junction, separated by a thin region of semiconductor known as the base region. (Two junction diodes wired together without sharing an intervening semiconducting region will not make a transistor.)

BJTs have three terminals, corresponding to the three layers of semiconductor—an ''emitter'', a ''base'', and a ''collector''. They are useful in [[amplifier]]s because the currents at the emitter and collector are controllable by a relatively small base current.<ref name=Streetman>{{cite book|last=Streetman|first=Ben|author-link=Ben G. Streetman|title=Solid State Electronic Devices|year=1992|publisher=Prentice-Hall|location=Englewood Cliffs, NJ|isbn=978-0-13-822023-5|pages=301–305}}</ref> In an n–p–n transistor operating in the active region, the emitter-base junction is forward-biased ([[electron]]s and [[electron hole|holes]] recombine at the junction), and the base-collector junction is reverse-biased (electrons and holes are formed at, and move away from, the junction), and electrons are injected into the base region. Because the base is narrow, most of these electrons will diffuse into the reverse-biased base-collector junction and be swept into the collector; perhaps one-hundredth of the electrons will recombine in the base, which is the dominant mechanism in the base current. As well, as the base is lightly doped (in comparison to the emitter and collector regions), recombination rates are low, permitting more carriers to diffuse across the base region. By controlling the number of electrons that can leave the base, the number of electrons entering the collector can be controlled.<ref name=Streetman/> Collector current is approximately β (common-emitter current gain) times the base current. It is typically greater than 100 for small-signal transistors but can be smaller in transistors designed for high-power applications.

Unlike the field-effect transistor (see below), the BJT is a low-input-impedance device. Also, as the base-emitter voltage (''V''<sub>BE</sub>) is increased the base-emitter current and hence the collector-emitter current (''I''<sub>CE</sub>) increase exponentially according to the [[diode modelling#Shockley diode model|Shockley diode model]] and the [[Ebers-Moll model]]. Because of this exponential relationship, the BJT has a higher [[transconductance]] than the FET.

Bipolar transistors can be made to conduct by exposure to light because the absorption of photons in the base region generates a photocurrent that acts as a base current; the collector current is approximately β times the photocurrent. Devices designed for this purpose have a transparent window in the package and are called [[phototransistor]]s.

===Usage of MOSFETs and BJTs===
The [[MOSFET]] is by far the most widely used transistor for both [[digital circuit]]s as well as [[analog circuit]]s,<ref>{{cite web |title=MOSFET DIFFERENTIAL AMPLIFIER |url=http://sites.bu.edu/engcourses/files/2016/08/mosfet-differential-amplifier.pdf |website=[[Boston University]] |access-date=August 10, 2019}}</ref> accounting for 99.9% of all transistors in the world.<ref name="computerhistory2018"/> The [[bipolar junction transistor]] (BJT) was previously the most commonly used transistor during the 1950s to 1960s. Even after MOSFETs became widely available in the 1970s, the BJT remained the transistor of choice for many analog circuits such as amplifiers because of their greater linearity, up until MOSFET devices (such as [[power MOSFET]]s, [[LDMOS]] and [[RF CMOS]]) replaced them for most [[power electronic]] applications in the 1980s. In [[integrated circuit]]s, the desirable properties of MOSFETs allowed them to capture nearly all market share for digital circuits in the 1970s. Discrete MOSFETs (typically power MOSFETs) can be applied in transistor applications, including analog circuits, voltage regulators, amplifiers, power transmitters, and motor drivers.

===Other transistor types===
[[File:Transistor on portuguese pavement.jpg|thumb|A transistor symbol created on [[Portuguese pavement]] at the [[University of Aveiro]]]]
{{For|early bipolar transistors|Bipolar junction transistor#Bipolar transistors}}
* [[Field-effect transistor]] (FET):
** [[Metal–oxide–semiconductor field-effect transistor]] (MOSFET), where the gate is insulated by a shallow layer of insulator
*** [[PMOS logic|p-type MOS]] (PMOS)
*** [[NMOS logic|n-type MOS]] (NMOS)
*** [[CMOS|complementary MOS]] (CMOS)
**** [[RF CMOS]], for [[radiofrequency]] amplification, reception
*** [[Multi-gate field-effect transistor]] (MuGFET)
**** [[Fin field-effect transistor]] (FinFET), source/drain region shapes fins on the silicon surface
****GAAFET, Similar to FinFET but nanowires are used instead of fins, the nanowires are stacked vertically and are surrounded on 4 sides by the gate
****MBCFET, a variant of GAAFET that uses horizontal nanosheets instead of nanowires, made by Samsung. Also known as RibbonFET (made by Intel) and as horizontal nanosheet transistor.
*** [[Thin-film transistor]] (TFT), used in [[Liquid-crystal display|LCD]] and [[OLED]] displays, types include amorphous silicon, LTPS, LTPO and IGZO transistors 
*** [[Floating-gate MOSFET]] (FGMOS), for [[non-volatile storage]]
*** [[Power MOSFET]], for power electronics
**** [[LDMOS|lateral diffused MOS]] (LDMOS)
** [[Carbon nanotube field-effect transistor]] (CNFET, CNTFET), where the channel material is replaced by a carbon nanotube
** Ferroelectric field-effect transistor ([[Fe FET]]), uses ferroelectric materials
** [[Junction gate field-effect transistor]] (JFET), where the gate is insulated by a reverse-biased p–n junction
** [[Metal–semiconductor field-effect transistor]] (MESFET), similar to JFET with a Schottky junction instead of a p–n junction
*** [[High-electron-mobility transistor]] (HEMT): GaN (Gallium Nitride), SiC (Silicon Carbide), Ga<sub>2</sub>O<sub>3</sub> (Gallium Oxide), GaAs (Gallium Arsenide) transistors, MOSFETs, etc.
** Negative-Capacitance FET (NC-FET)
** [[Inverted-T field-effect transistor]] (ITFET)
** [[Fast-reverse epitaxial diode field-effect transistor]] (FREDFET)
** [[Organic field-effect transistor]] (OFET), in which the semiconductor is an organic compound
** [[Ballistic transistor (disambiguation)]]
** FETs used to sense the environment
*** [[Ion-sensitive field-effect transistor]] (ISFET), to measure ion concentrations in solution,
*** [[Electrolyte–oxide–semiconductor field-effect transistor]] (EOSFET), [[neurochip]],
*** [[Deoxyribonucleic acid field-effect transistor]] (DNAFET).
*** Field-effect transistor-based biosensor ([[Bio-FET]])
* [[Bipolar junction transistor]] (BJT):
** [[Heterojunction bipolar transistor]], up to several hundred GHz, common in modern ultrafast and RF circuits
** [[Schottky transistor]]
** [[avalanche transistor]]
** [[File: Darlington transistor MJ1000.jpg|thumb|A [[Darlington transistor]] with the upper case removed so the transistor chip (the small square) can be seen. It is effectively two transistors on the same chip. One is much larger than the other, but both are large in comparison to transistors in [[large-scale integration]] because this particular example is intended for power applications.]] [[Darlington transistor]]s are two BJTs connected together to provide a high current gain equal to the product of the current gains of the two transistors
** [[Insulated-gate bipolar transistor]]s (IGBTs) use a medium-power IGFET, similarly connected to a power BJT, to give a high input impedance. Power diodes are often connected between certain terminals depending on specific use. IGBTs are particularly suitable for heavy-duty industrial applications. The [[ASEA Brown Boveri]] (ABB) ''5SNA2400E170100'' ,<ref>{{cite web |url=http://library.abb.com/GLOBAL/SCOT/scot256.nsf/VerityDisplay/E700072B04381DD9C12571FF002D2CFE/$File/5SNA%202400E170100_5SYA1555-03Oct%2006.pdf |title=IGBT Module 5SNA 2400E170100 |access-date=June 30, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120426020121/http://library.abb.com/GLOBAL/SCOT/scot256.nsf/VerityDisplay/E700072B04381DD9C12571FF002D2CFE/$File/5SNA%202400E170100_5SYA1555-03Oct%2006.pdf |archive-date=April 26, 2012 }}</ref> intended for three-phase power supplies, houses three n–p–n IGBTs in a case measuring 38 by 140 by 190&nbsp;mm and weighing 1.5&nbsp;kg. Each IGBT is rated at 1,700 volts and can handle 2,400 amperes
** [[Phototransistor]].
** [[Emitter-switched bipolar transistor]] (ESBT) is a monolithic configuration of a high-voltage bipolar transistor and a low-voltage power MOSFET in [[cascode]] topology. It was introduced by STMicroelectronics in the 2000s,<ref>{{cite conference |doi=10.1109/IAS.2003.1257745 |title=A new monolithic emitter-switching bipolar transistor (ESBT) in high-voltage converter applications |first1=S. |last1=Buonomo |first2=C. |last2=Ronsisvalle |first3=R. |last3=Scollo |author4=STMicroelectronics  |author-link4=STMicroelectronics |first5=S. |last5=Musumeci |first6=R. |last6=Pagano |first7=A. |last7=Raciti |author8= University of Catania Italy |author-link8=University of Catania |date=October 16, 2003 |conference=38th IAS annual Meeting on Conference Record of the Industry Applications Conference |editor=IEEE |editor-link=Institute of Electrical and Electronics Engineers |volume=3 of 3 |location=Salt Lake City |pages=1810–1817  }}</ref> and abandoned a few years later around 2012.<ref>{{cite web |url=https://www.st.com/en/power-transistors/esbts.html?querycriteria=productId=SC1775 |title=ESBTs  |author=STMicroelectronics  |author-link=STMicroelectronics  |website=www.st.com|access-date=February 17, 2019 |quote=ST no longer offers these components, this web page is empty, and datasheets are obsoletes  }}</ref>
** [[Multiple-emitter transistor]], used in [[transistor–transistor logic]] and integrated current mirrors
** [[Multiple-base transistor]], used to amplify very-low-level signals in noisy environments such as the pickup of a [[record player]] or [[RF front end|radio front ends]]. Effectively, it is a very large number of transistors in parallel where, at the output, the signal is added constructively, but random noise is added only [[stochastic]]ally.<ref>Zhong Yuan Chang, Willy M. C. Sansen, ''Low-Noise Wide-Band Amplifiers in Bipolar and CMOS Technologies'', page 31, Springer, 1991 {{ISBN|0792390962}}.</ref>
* [[Tunnel field-effect transistor]], where it switches by modulating [[quantum tunneling]] through a barrier.
* [[Diffusion transistor]], formed by diffusing dopants into semiconductor substrate; can be both BJT and FET.
* [[Unijunction transistor]], which can be used as a simple pulse generator. It comprises the main body of either p-type or n-type semiconductor with ohmic contacts at each end (terminals ''Base1'' and ''Base2''). A junction with the opposite semiconductor type is formed at a point along the length of the body for the third terminal (''Emitter'').
* [[Single-electron transistor]]s (SET), consist of a gate island between two tunneling junctions. The tunneling current is controlled by a voltage applied to the gate through a capacitor.<ref>{{cite web |url=http://snow.stanford.edu/~shimbo/set.html |title=Single Electron Transistors |publisher=Snow.stanford.edu |access-date=June 30, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120426015942/http://snow.stanford.edu/~shimbo/set.html |archive-date=April 26, 2012 }}</ref>
* [[Nanofluidic transistor]], controls the movement of ions through sub-microscopic, water-filled channels.<ref>{{cite web |last=Sanders |first=Robert |url=http://www.berkeley.edu/news/media/releases/2005/06/28_transistor.shtml |title=Nanofluidic transistor, the basis of future chemical processors |publisher=Berkeley.edu |date=June 28, 2005 |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120702182324/http://www.berkeley.edu/news/media/releases/2005/06/28_transistor.shtml |archive-date=July 2, 2012 }}</ref>
* [[Multigate device]]s:
** [[Tetrode transistor]]
** [[Pentode transistor]]
** [[Trigate transistor]] (prototype by Intel)
** [[Dual-gate field-effect transistor]]s have a single channel with two gates in [[cascode]], a configuration optimized for ''high-frequency amplifiers'', ''mixers'', and [[oscillators]].
* [[Junctionless nanowire transistor]] (JNT), uses a simple nanowire of silicon surrounded by an electrically isolated "wedding ring" that acts to gate the flow of electrons through the wire. 
* [[Nanoscale vacuum-channel transistor]], when in 2012, NASA and the National Nanofab Center in South Korea were reported to have built a prototype vacuum-channel transistor in only 150 nanometers in size, can be manufactured cheaply using standard silicon semiconductor processing, can operate at high speeds even in hostile environments, and could consume just as much power as a standard transistor.<ref>{{cite web |url=http://www.gizmag.com/nasa-vacuum-channel-transistor/22626/ |title=The return of the vacuum tube? |publisher=Gizmag.com |date=May 28, 2012 |access-date=May 1, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160414122940/http://www.gizmag.com/nasa-vacuum-channel-transistor/22626/ |archive-date=April 14, 2016 }}</ref>
* [[Organic electrochemical transistor]].
* [[Solaristor]] (from solar cell transistor), a two-terminal gate-less self-powered phototransistor.
* Germanium–Tin Transistor<ref>{{cite web | url=https://www.azom.com/news.aspx?newsID=61206 | title=New Type of Transistor from a Germanium–Tin Alloy Developed | date=April 28, 2023 }}</ref>
* Wood transistor<ref>{{cite web | url=https://spectrum.ieee.org/wood-transistor | title=Timber! The World's First Wooden Transistor - IEEE Spectrum }}</ref><ref>{{cite web | url=https://www.theregister.com/2023/05/01/wooden_transistor_sweden/ | title=Boffins claim to create the world's first wooden transistor }}</ref>
* Paper transistor<ref>{{Cite web|url=https://spectrum.ieee.org/paper-transistor|title=Paper Transistor - IEEE Spectrum|website=spectrum.ieee.org}}</ref>
* [[Communicant Semiconductor Technologies|Carbon-doped silicon-germanium (Si-Ge:C)]] transistor
* Diamond transistor<ref>{{Cite web|url=https://spectrum.ieee.org/this-diamond-transistor-is-still-raw-but-its-future-looks-bright|title=This Diamond Transistor Is Still Raw, But Its Future Looks Bright - IEEE Spectrum|website=spectrum.ieee.org}}</ref>
* Aluminum nitride transistor<ref>{{Cite web|url=https://spectrum.ieee.org/aluminum-nitride|title=The New, New Transistor - IEEE Spectrum|website=spectrum.ieee.org}}</ref>
* Super-lattice castellated field effect transistors<ref>{{Cite web|url=https://semiengineering.com/chip-industry-week-in-review-23/|title=Chip Industry Week In Review|first=The SE|last=Staff|date=February 23, 2024|website=Semiconductor Engineering}}</ref>

==Device identification==
Three major identification standards are used for designating transistor devices. In each, the alphanumeric prefix provides clues to the type of the device.

===Joint Electron Device Engineering Council (JEDEC)===
The [[JEDEC]] part numbering scheme evolved in the 1960s in the United States. The JEDEC ''EIA-370'' transistor device numbers usually start with ''2N'', indicating a three-terminal device. Dual-gate [[field-effect transistor]]s are four-terminal devices, and begin with 3N. The prefix is followed by a two-, three- or four-digit number with no significance as to device properties, although early devices with low numbers tend to be germanium devices. For example, [[2N3055]] is a silicon n–p–n power transistor, 2N1301 is a p–n–p germanium switching transistor. A letter suffix, such as "A", is sometimes used to indicate a newer variant, but rarely gain groupings.

{|class="wikitable"
|+ JEDEC prefix table
|-
! Prefix !! Type and usage
|-
|1N || two-terminal device, such as diodes
|-
|2N || three-terminal device, such as transistors or single-gate [[field-effect transistor]]s
|-
|3N || four-terminal device, such as dual-gate field-effect transistors
|}

===Japanese Industrial Standard (JIS)===
In Japan, the [[JIS semiconductor designation]] (|JIS-C-7012), labels transistor devices starting with ''2S'',<ref>{{cite web |url=http://www.clivetec.0catch.com/Transistors.htm#JIS |title=Transistor Data |publisher=Clivetec.0catch.com |access-date=May 1, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160426190413/http://www.clivetec.0catch.com/Transistors.htm#JIS |archive-date=April 26, 2016 }}</ref> e.g., 2SD965, but sometimes the "2S" prefix is not marked on the package–a 2SD965 might only be marked ''D965'' and a 2SC1815 might be listed by a supplier as simply ''C1815''. This series sometimes has suffixes, such as ''R'', ''O'', ''BL'', standing for ''red'', ''orange'', ''blue'', etc., to denote variants, such as tighter ''h''<sub>FE</sub> (gain) groupings.

{|class="wikitable"
|+ JIS transistor prefix table
|-
! Prefix !! Type and usage
|-
|2SA || high-frequency p–n–p BJT
|-
|2SB || audio-frequency p–n–p BJT
|-
|2SC || high-frequency n–p–n BJT
|-
|2SD || audio-frequency n–p–n BJT
|-
|2SJ || P-channel FET (both JFET and MOSFET)
|-
|2SK || N-channel FET (both JFET and MOSFET)
|}

===European Electronic Component Manufacturers Association (EECA)===
The European Electronic Component Manufacturers Association (EECA) uses a numbering scheme that was inherited from [[Pro Electron]] when it merged with EECA in 1983. This scheme begins with two letters: the first gives the semiconductor type (A for germanium, B for silicon, and C for materials like GaAs); the second letter denotes the intended use (A for diode, C for general-purpose transistor, etc.). A three-digit sequence number (or one letter and two digits, for industrial types) follows. With early devices this indicated the case type. Suffixes may be used, with a letter (e.g. "C" often means high ''h''<sub>FE</sub>, such as in: BC549C<ref>{{cite web |url=http://www.fairchildsemi.com/ds/BC/BC549.pdf |title=Datasheet for BC549, with A, B and C gain groupings |access-date=June 30, 2012 |website=Fairchild Semiconductor |url-status=live |archive-url=https://web.archive.org/web/20120407001013/http://www.fairchildsemi.com/ds/BC/BC549.pdf |archive-date=April 7, 2012 }}</ref>) or other codes may follow to show gain (e.g. BC327-25) or voltage rating (e.g. BUK854-800A<ref>{{cite web |url=http://www.datasheetcatalog.org/datasheet/philips/BUK854-800A.pdf |title=Datasheet for BUK854-800A (800volt IGBT) |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120415132635/http://www.datasheetcatalog.org/datasheet/philips/BUK854-800A.pdf |archive-date=April 15, 2012 }}</ref>). The more common prefixes are:

{|class="wikitable"
|+ EECA transistor prefix table
|-
! Prefix !! Type and usage !! Example !! Equivalent !! Reference
|-
|AC || [[Germanium]], small-signal [[Audio Frequency|AF]] transistor || AC126 || NTE102A || 
|-
|AD || Germanium, [[Audio Frequency|AF]] power transistor || AD133 || NTE179 || 
|-
|AF || Germanium, small-signal [[Radio Frequency|RF]] transistor || AF117 || NTE160 || 
|-
|AL || Germanium, [[Radio Frequency|RF]] power transistor || ALZ10 || NTE100 || 
|-
|AS || Germanium, switching transistor || ASY28 || NTE101 || 
|-
|AU || Germanium, power switching transistor || AU103 || NTE127 || 
|-
|BC || [[Silicon]], small-signal transistor ("general purpose") || BC548 || [[2N3904]] || [https://www.mccsemi.com/pdf/Products/2N3904(TO-92).pdf Datasheet]
|-
|BD || Silicon, power transistor || BD139 || NTE375 || [http://www.fairchildsemi.com/ds/BD/BD135.pdf Datasheet]
|-
|BF || Silicon, [[Radio Frequency|RF]] (high frequency) [[BJT]] or [[FET]] || BF245 || NTE133 || [http://www.onsemi.com/pub_link/Collateral/BF245A-D.PDF Datasheet]
|-
|BS || Silicon, switching transistor (BJT or [[MOSFET]]) || [[BS170]] || [[2N7000]] || [http://www.fairchildsemi.com/ds/BS/BS170.pdf Datasheet]
|-
|BL || Silicon, high frequency, high power (for transmitters) || BLW60 || NTE325 || [http://www.datasheetcatalog.org/datasheet/philips/BLW60.pdf Datasheet]
|-
|BU || Silicon, high voltage (for [[cathode-ray tube|CRT]] horizontal deflection circuits) || BU2520A || NTE2354 || [http://www.datasheetcatalog.org/datasheet/philips/BU2520A.pdf Datasheet]
|-
|CF || [[Gallium arsenide]], small-signal [[microwave]] transistor ([[MESFET]])&nbsp;|| CF739 || — || [https://web.archive.org/web/20150109012745/http://www.kesun.com/pdf/rf%20transistor/CF739.pdf Datasheet]
|-
|CL || Gallium arsenide, [[microwave]] power transistor ([[Field-effect transistor|FET]]) || CLY10 || — || [http://www.datasheetcatalog.org/datasheet/siemens/CLY10.pdf Datasheet]
|}

===Proprietary===
Manufacturers of devices may have their proprietary numbering system, for example [[CK722]]. Since devices are [[Second source|second-sourced]], a manufacturer's prefix (like "MPF" in MPF102, which originally would denote a [[Motorola]] [[FET]]) now is an unreliable indicator of who made the device. Some proprietary naming schemes adopt parts of other naming schemes, for example, a PN2222A is a (possibly [[Fairchild Semiconductor]]) 2N2222A in a plastic case (but a PN108 is a plastic version of a BC108, not a 2N108, while the PN100 is unrelated to other xx100 devices).

Military part numbers sometimes are assigned their codes, such as the [[UK CV series|British Military CV Naming System]].

Manufacturers buying large numbers of similar parts may have them supplied with "house numbers", identifying a particular purchasing specification and not necessarily a device with a standardized registered number. For example, an HP part 1854,0053 is a (JEDEC) 2N2218 transistor<ref>{{cite web |url=http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv010.cgi?read=27258 |title=Richard Freeman's HP Part numbers Crossreference |publisher=Hpmuseum.org |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120605183505/http://www.hpmuseum.org/cgi-sys/cgiwrap/hpmuseum/archv010.cgi?read=27258 |archive-date=June 5, 2012 }}</ref><ref>{{cite web |url=http://www.sphere.bc.ca/test/hp-parts/300-hpxref.pdf |title=Transistor–Diode Cross Reference – H.P. Part Numbers to JEDEC (pdf) |access-date=May 1, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160508135527/http://www.sphere.bc.ca/test/hp-parts/300-hpxref.pdf |archive-date=May 8, 2016 }}</ref> which is also assigned the CV number: CV7763<ref>{{cite web |url=http://www.qsl.net/g8yoa/cv_table.html |title=CV Device Cross-reference by Andy Lake |publisher=Qsl.net |access-date=June 30, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120121111531/http://www.qsl.net/g8yoa/cv_table.html |archive-date=January 21, 2012 }}</ref>

===Naming problems===
With so many independent naming schemes, and the abbreviation of part numbers when printed on the devices, ambiguity sometimes occurs. For example, two different devices may be marked "J176" (one the J176 low-power [[JFET]], the other the higher-powered [[MOSFET]] 2SJ176).

As older "through-hole" transistors are given [[Surface-mount technology|surface-mount]] packaged counterparts, they tend to be assigned many different part numbers because manufacturers have their systems to cope with the variety in [[pinout]] arrangements and options for dual or matched n–p–n + p–n–p devices in one pack. So even when the original device (such as a 2N3904) may have been assigned by a standards authority, and well known by engineers over the years, the new versions are far from standardized in their naming.

==Construction==
{{More citations needed section|date=June 2021}}

===Semiconductor material===
{|class="wikitable" style="float:right; margin:10px;"
|+ Semiconductor material characteristics
|-
! Semiconductor <br/>material
! Junction forward <br/>voltage @ 25&nbsp;°C, V 
! Electron mobility <br/>@ 25&nbsp;°C, m<sup>2</sup>/(V·s)
! Hole mobility <br/>@ 25&nbsp;°C, m<sup>2</sup>/(V·s)
! {{abbr|Max.|Maximum}} junction <br/>{{abbr|temp.|temperature}}, °C
|-
! Ge
|0.27||0.39||0.19||70 to 100
|-
! Si
|0.71||0.14|| 0.05||150 to 200
|-
! GaAs
|1.03||0.85||0.05||150 to 200
|-
! Al–Si junction
|0.3||—||—||150 to 200
|}

The first BJTs were made from [[germanium]] (Ge). [[Silicon]] (Si) types currently predominate but certain advanced microwave and high-performance versions now employ the ''compound semiconductor'' material [[gallium arsenide]] (GaAs) and the ''semiconductor alloy'' [[silicon-germanium]] (SiGe). Single-element semiconductor material (Ge and Si) is described as ''elemental''.

Rough parameters for the most common semiconductor materials used to make transistors are given in the adjacent table. These parameters will vary with an increase in temperature, electric field, impurity level, strain, and sundry other factors.

The ''junction forward voltage'' is the voltage applied to the emitter-base junction of a BJT to make the base conduct a specified current. The current increases exponentially as the junction forward voltage is increased. The values given in the table are typical for a current of 1&nbsp;mA (the same values apply to semiconductor diodes). The lower the junction forward voltage the better, as this means that less power is required to "drive" the transistor. The junction forward voltage for a given current decreases with an increase in temperature. For a typical silicon junction, the change is −2.1&nbsp;mV/°C.<ref name=Sedra>{{cite book |author1=Sedra, A.S. |author2=Smith, K.C. |name-list-style=amp |title=Microelectronic circuits |url=https://archive.org/details/microelectronicc00sedr_571 |url-access=limited |year=2004 |page=[https://archive.org/details/microelectronicc00sedr_571/page/n426 397] and Figure 5.17 |publisher=Oxford University Press |edition=Fifth |location=New York |isbn=978-0-19-514251-8}}</ref> In some circuits special compensating elements ([[sensistor]]s) must be used to compensate for such changes.

The density of mobile carriers in the channel of a MOSFET is a function of the electric field forming the channel and of various other phenomena such as the impurity level in the channel. Some impurities, called dopants, are introduced deliberately in making a MOSFET, to control the MOSFET electrical behavior.

The ''[[electron mobility]]'' and ''[[hole mobility]]'' columns show the average speed that electrons and holes diffuse through the semiconductor material with an [[electric field]] of 1&nbsp;volt per meter applied across the material. In general, the higher the electron mobility the faster the transistor can operate. The table indicates that Ge is a better material than Si in this respect. However, Ge has four major shortcomings compared to silicon and gallium arsenide:
# Its maximum temperature is limited.
# It has relatively high [[Reverse leakage current|leakage current]].
# It cannot withstand high voltages.
# It is less suitable for fabricating integrated circuits.
Because the electron mobility is higher than the hole mobility for all semiconductor materials, a given bipolar [[n–p–n transistor]] tends to be swifter than an equivalent [[p–n–p transistor]]. GaAs has the highest electron mobility of the three semiconductors. It is for this reason that GaAs is used in high-frequency applications. A relatively recent{{When|date=May 2018}} FET development, the ''[[high-electron-mobility transistor]]'' (HEMT), has a [[heterojunction|heterostructure]] (junction between different semiconductor materials) of aluminium gallium arsenide (AlGaAs)-gallium arsenide (GaAs) which has twice the electron mobility of a GaAs-metal barrier junction. Because of their high speed and low noise, HEMTs are used in satellite receivers working at frequencies around 12&nbsp;GHz. HEMTs based on [[gallium nitride]] and [[aluminum gallium nitride]] (AlGaN/GaN HEMTs) provide still higher electron mobility and are being developed for various applications.

Maximum [[junction temperature]] values represent a cross-section taken from various manufacturers' datasheets. This temperature should not be exceeded or the transistor may be damaged.

''Al–Si junction'' refers to the high-speed (aluminum-silicon) metal–semiconductor barrier diode, commonly known as a [[Schottky diode]]. This is included in the table because some silicon power IGFETs have a [[parasitic structure|parasitic]] reverse Schottky diode formed between the source and drain as part of the fabrication process. This diode can be a nuisance, but sometimes it is used in the circuit.

===Packaging===
{{See also|Semiconductor package|Chip carrier}}
[[File:Transbauformen.jpg|thumb|Assorted discrete transistors]]
[[File:Kt315b.jpg|thumb|[[Soviet Union|Soviet]]-manufactured [[KT315]]b transistors]]
Discrete transistors can be individually packaged transistors or unpackaged transistor chips.

Transistors come in many different [[semiconductor package]]s (see image). The two main categories are ''[[through-hole technology|through-hole]]'' (or ''leaded''), and ''surface-mount'', also known as ''surface-mount device'' ([[surface-mount technology|SMD]]). The ''ball grid array'' ([[Ball grid array|BGA]]) is the latest surface-mount package. It has solder "balls" on the underside in place of leads. Because they are smaller and have shorter interconnections, SMDs have better high-frequency characteristics but lower power ratings.

Transistor packages are made of glass, metal, ceramic, or plastic. The package often dictates the power rating and frequency characteristics. Power transistors have larger packages that can be clamped to [[heat sink]]s for enhanced cooling. Additionally, most power transistors have the collector or drain physically connected to the metal enclosure. At the other extreme, some surface-mount ''microwave'' transistors are as small as grains of sand.

Often a given transistor type is available in several packages. Transistor packages are mainly standardized, but the assignment of a transistor's functions to the terminals is not: other transistor types can assign other functions to the package's terminals. Even for the same transistor type the terminal assignment can vary (normally indicated by a suffix letter to the part number, q.e. BC212L and BC212K).

Nowadays most transistors come in a wide range of SMT packages. In comparison, the list of available through-hole packages is relatively small. Here is a short list of the most common through-hole transistors packages in alphabetical order:
ATV, E-line, MRT, HRT, SC-43, SC-72, TO-3, TO-18, TO-39, TO-92, TO-126, TO220, TO247, TO251, TO262, ZTX851.

Unpackaged transistor chips (die) may be assembled into hybrid devices.<ref name="Greig">{{cite book
 |last=Greig |first=William
 |date=April 24, 2007
|title=Integrated Circuit Packaging, Assembly and Interconnections
 |url=https://books.google.com/books?id=g29xoTAyAMgC&q=hybrid+&pg=PA63 
 |page=63 
 |publisher=Springer
 |quote=A hybrid circuit is defined as an assembly containing both active semiconductor devices (packaged and unpackaged)|isbn=9780387339139
 }}</ref>  The [[IBM SLT]] module of the 1960s is one example of such a hybrid circuit module using glass passivated transistor (and diode) die.  Other packaging techniques for discrete transistors as chips include ''direct chip attach'' (DCA) and ''chip-on-board'' (COB).<ref name="Greig"/>

====Flexible transistors====
Researchers have made several kinds of flexible transistors, including [[organic field-effect transistor]]s.<ref>{{cite journal|title=Can We Build a Truly High Performance Computer Which is Flexible and Transparent? |journal=Scientific Reports |volume=3 |pages=2609 |doi=10.1038/srep02609 |year=2013 |last1=Rojas |first1=Jhonathan P. |last2=Torres Sevilla |first2=Galo A. |last3=Hussain |first3=Muhammad M. |bibcode = 2013NatSR...3E2609R |pmid=24018904 |pmc=3767948}}</ref><ref>{{cite journal|doi=10.1088/0022-3727/45/14/143001|title=Fast flexible electronics using {{sic|transferrable|nolink=y}} silicon nanomembranes|journal=Journal of Physics D: Applied Physics|volume=45|issue=14|pages=143001|year=2012|last1=Zhang|first1=Kan|last2=Seo|first2=Jung-Hun|last3=Zhou|first3=Weidong|last4=Ma|first4=Zhenqiang|bibcode = 2012JPhD...45n3001Z |s2cid=109292175}}
</ref><ref>{{cite journal|doi=10.1038/NNANO.2011.1 |pmid=21297625 |title=Flexible high-performance carbon nanotube integrated circuits |journal=Nature Nanotechnology |volume=6 |issue=3 |pages=156–61 |year=2011 |last1=Sun |first1=Dong-Ming |last2=Timmermans |first2=Marina Y. |last3=Tian |first3=Ying |last4=Nasibulin |first4=Albert G. |last5=Kauppinen |first5=Esko I. |last6=Kishimoto |first6=Shigeru |last7=Mizutani |first7=Takashi |last8=Ohno |first8=Yutaka |bibcode = 2011NatNa...6..156S |s2cid=205446925 }}</ref> Flexible transistors are useful in some kinds of [[flexible display]]s and other [[flexible electronics]].

==See also==
{{Portal|Electronics}}
{{div col|colwidth=20em}}
* [[Band gap]]
* [[Digital electronics]]
*[[Diffused junction transistor]]
* [[Moore's law]]
* [[Optical transistor]]
* [[Magneto-Electric Spin-Orbit]]
* [[Nanoelectromechanical relay]]
* [[Semiconductor device modeling]]
* [[Transistor count]]
* [[Transistor model]]
* [[Transresistance]]
* [[Very Large Scale Integration]]
* [[Trancitor]]
{{div col end}}

==References==
{{Reflist|30em}}

==Further reading==
;Books
* {{cite book|author=[[Paul Horowitz|Horowitz, Paul]] & Hill, Winfield|title=The Art of Electronics|publisher=Cambridge University Press|year=2015|edition=3|isbn=978-0521809269|title-link=The Art of Electronics}}
* {{cite book|vauthors=Amos SW, James MR |title=Principles of Transistor Circuits|publisher=Butterworth-Heinemann|year=1999|isbn=978-0-7506-4427-3}}
* {{cite book|author1=Riordan, Michael  |author2=Hoddeson, Lillian |name-list-style=amp |title=Crystal Fire|publisher=W.W Norton & Company Limited|year=1998|isbn=978-0-393-31851-7}} The invention of the transistor & the birth of the information age
* {{cite book|author=Warnes, Lionel|title=Analogue and Digital Electronics|publisher=Macmillan Press Ltd|year=1998|isbn=978-0-333-65820-8}}
* ''The Power Transistor - Temperature and Heat Transfer''; 1st Ed; John McWane, Dana Roberts, Malcom Smith; McGraw-Hill; 82 pages; 1975; {{ISBN|978-0-07-001729-0}}. <small>[https://archive.org/details/ThePowerTransistor/ (archive)]</small>
* ''Transistor Circuit Analysis - Theory and Solutions to 235 Problems''; 2nd Ed; Alfred Gronner; Simon and Schuster; 244 pages; 1970. <small>[https://archive.org/details/TransistorCircuitAnalysis/ (archive)]</small>
* ''Transistor Physics and Circuits''; R.L. Riddle and M.P. Ristenbatt; Prentice-Hall; 1957.

;Periodicals
* {{cite journal|author=Michael Riordan|year=2005|title=How Europe Missed the Transistor|journal=IEEE Spectrum|volume=42|issue=11|pages=52–57|url=https://spectrum.ieee.org/print/2155|doi=10.1109/MSPEC.2005.1526906|s2cid=34953819|url-status=dead|archive-url=https://web.archive.org/web/20080214002109/http://www.spectrum.ieee.org/print/2155|archive-date=February 14, 2008}}
* {{cite news|title=Herbert F. Mataré, An Inventor of the Transistor has his moment|date=February 24, 2003|newspaper=The New York Times|url=http://www.mindfully.org/Technology/2003/Transistor-Matare-Inventor24feb03.htm|url-status=dead|archive-url=https://web.archive.org/web/20090623050755/http://www.mindfully.org/Technology/2003/Transistor-Matare-Inventor24feb03.htm|archive-date=June 23, 2009}}
* {{cite journal|author=Bacon, W. Stevenson|year=1968|title=The Transistor's 20th Anniversary: How Germanium And A Bit of Wire Changed The World|url=https://books.google.com/books?id=mykDAAAAMBAJ|journal=Popular Science|volume=192|issue=6|pages=80–84|issn=0161-7370}}

;Databooks
* [https://archive.org/details/bitsavers_fairchilddldDiscreteDataBook_35122751 Discrete Databook]; 1985; Fairchild (now ON Semiconductor)
* [https://archive.org/details/bitsavers_motoroladaSmallSignalSemiconductors_75896318/ Small-Signal Semiconductors Databook], 1987; Motorola (now ON semiconductor)
* [https://archive.org/details/bitsavers_sgsdataBooDevices5ed_46325378 Discrete Power Devices Databook]; 1982; SGS (now STMicroelectronics)
* [https://archive.org/details/NationalSemiconductor-DiscreteDatabook1978OCR Discrete Databook]; 1978; National Semiconductor (now Texas Instruments)

==External links==
{{Commons category multi|Transistors|Transistors (SMD)}}
{{Wikibooks|Transistors}}
* [http://news.bbc.co.uk/2/hi/technology/7091190.stm BBC: Building the digital age] photo history of transistors
* [https://web.archive.org/web/20070928041118/http://www.porticus.org/bell/belllabs_transistor.html The Bell Systems Memorial on Transistors]
* [http://www.ieeeghn.org/wiki/index.php/The_Transistor_and_Portable_Electronics ''IEEE Global History Network, The Transistor and Portable Electronics'']. All about the history of transistors and integrated circuits.
* [http://www.aps.org/publications/apsnews/200011/history.cfm ''This Month in Physics History: November 17 to December 23, 1947: Invention of the First Transistor'']. From the [[American Physical Society]]
* [https://www.britannica.com/technology/transistor Transistor | Definition & Uses | Britannica] "Transistor" at ''[[Encyclopædia Britannica]]''

{{Electronic components}}
{{Digital electronics}}
{{Authority control}}

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