Editing Bipolar junction transistor (section)

== History ==
The bipolar point-contact transistor was invented in December 1947<ref>{{cite web |url=http://www.computerhistory.org/semiconductor/timeline/1947-invention.html |title=1947: Invention of the Point-Contact Transistor |publisher=[[Computer History Museum]] |access-date=August 10, 2016 }}</ref> at the [[Bell Telephone Laboratories]] by [[John Bardeen]] and [[Walter Brattain]] under the direction of [[William Shockley]]. The junction version known as the bipolar junction transistor (BJT), invented by Shockley in 1948,<ref>{{cite web |url=http://www.computerhistory.org/semiconductor/timeline/1948-conception.html |title=1948: Conception of the Junction Transistor |publisher=Computer History Museum |access-date=August 10, 2016 }}</ref> was for three decades the device of choice in the design of discrete and [[integrated circuits]]. Nowadays, the use of the BJT has declined in favor of CMOS technology in the design of digital integrated circuits. The incidental low performance BJTs inherent in CMOS ICs, however, are often utilized as [[bandgap voltage reference]], [[silicon bandgap temperature sensor]] and to handle [[electrostatic discharge]].

=== Germanium transistors ===
The germanium transistor was more common in the 1950s and 1960s but has a greater tendency to exhibit [[thermal runaway]]. Since [[Diode#Forward bias|germanium p-n junctions have a lower forward bias]] than silicon, germanium transistors turn on at lower voltage.

=== Early manufacturing techniques ===
Various methods of manufacturing bipolar transistors were developed.<ref>[http://hm-treasury.gov.uk/media/B/C/queen_mary_ip_research_institute_p5_043_762kb.pdf Third case study – the solid state advent] {{webarchive |url=https://web.archive.org/web/20070927032750/http://hm-treasury.gov.uk/media/B/C/queen_mary_ip_research_institute_p5_043_762kb.pdf |date=September 27, 2007 }} (PDF)</ref>
* [[Point-contact transistor]]&nbsp;– first transistor ever constructed (December 1947), a bipolar transistor, limited commercial use due to high cost and noise.
** [[Tetrode transistor#Early tetrode transistors|Tetrode point-contact transistor]] – Point-contact transistor having two emitters. It became obsolete in the middle 1950s.
* Junction transistors
** [[Grown-junction transistor]]{{spaced ndash}} first bipolar ''junction'' transistor made.<ref>{{cite web |url=http://semiconductormuseum.com/PhotoGallery/PhotoGallery_M1752.htm |title=Transistor Museum, Historic Transistor Photo Gallery, Bell Labs Type M1752 }}</ref> Invented by William Shockley at [[Bell Labs]] on June 23, 1948.<ref>{{cite book |last=Morris |first=Peter Robin |title=A History of the World Semiconductor Industry |series=IEE History of Technology Series 12 |date=1990 |publisher=Peter Peregrinus Ltd. |location=London |isbn=978-0-86341-227-1 |page=29 |chapter=4.2 }}</ref> Patent filed on June 26, 1948.
** [[Alloy-junction transistor]]{{spaced ndash}} emitter and collector alloy beads fused to base. Developed at [[General Electric]] and [[RCA]]<ref>{{cite web |url=http://semiconductormuseum.com/PhotoGallery/PhotoGallery_TA153.htm |title=Transistor Museum Photo Gallery RCA TA153 |access-date=August 10, 2016}}</ref> in 1951.
*** [[Micro-alloy transistor]] (MAT){{spaced ndash}} high-speed type of alloy junction transistor. Developed at [[Philco]].<ref>{{cite book |title=High Speed Switching Transistor Handbook |date=1963 |publisher=Motorola |edition=2nd |page=17}}[https://groups.google.com/group/sci.electronics.components/tree/browse_frm/month/2003-04/c97c04dc783ab61e?rnum=21&_done=%2Fgroup%2Fsci.electronics.components%2Fbrowse_frm%2Fmonth%2F2003-04%3F].</ref>
*** [[Micro-alloy diffused transistor]] (MADT){{spaced ndash}} high-speed type of alloy junction transistor, speedier than MAT, a [[diffused-base transistor]]. Developed at Philco.
*** [[Post-alloy diffused transistor]] (PADT){{spaced ndash}} high-speed type of alloy junction transistor, speedier than MAT, a diffused-base transistor. Developed at [[Philips]].
** [[Tetrode transistor]]{{spaced ndash}} high-speed variant of grown-junction transistor<ref>[http://semiconductormuseum.com/PhotoGallery/PhotoGallery_3N22.htm Transistor Museum, Historic Transistor Photo Gallery, Western Electric 3N22].</ref> or alloy junction transistor<ref>{{cite journal|doi=10.1109/T-ED.1957.14192|title=The tetrode power transistor|journal=IRE Transactions on Electron Devices|volume=4|issue=1|pages=1–5|date=1957|last=Maupin|first=J.T.|bibcode=1957ITED....4....1M|s2cid=51668235}}</ref> with two connections to base.
** [[Surface-barrier transistor]]{{spaced ndash}} high-speed metal-barrier junction transistor. Developed at Philco<ref>{{cite web |url=http://semiconductormuseum.com/PhotoGallery/PhotoGallery_A01.htm |title=Transistor Museum Photo Gallery Philco A01 Germanium Surface Barrier Transistor |access-date=August 10, 2016 }}</ref> in 1953.<ref>{{cite web |url=http://semiconductormuseum.com/PhotoGallery/PhotoGallery_SurfaceBarrier.htm |title=Transistor Museum Photo Gallery Germanium Surface Barrier Transistor |access-date=August 10, 2016 }}</ref>
** [[Drift-field transistor]]{{spaced ndash}} high-speed bipolar junction transistor. Invented by [[Herbert Kroemer]]<ref>{{cite journal |doi=10.1109/16.960370 |title=Herb's bipolar transistors |journal=IEEE Transactions on Electron Devices |volume=48 |issue=11 |pages=2473–2476 |date=2001 |last1=Brar |first1=B. |last2=Sullivan |first2=G.J. |last3=Asbeck |first3=P.M. |bibcode=2001ITED...48.2473B }}</ref><ref>{{cite journal |doi=10.1109/T-ED.1967.15902 |title=Influence of mobility and lifetime variations on drift-field effects in silicon-junction devices |journal=IEEE Transactions on Electron Devices |volume=14 |issue=2 |pages=75–81 |date=1967 |last1=Bullis |first1=W.M. |last2=Runyan |first2=W.R. |bibcode=1967ITED...14...75B }}</ref> at the Central Bureau of Telecommunications Technology of the German Postal Service, in 1953.
** [[Spacistor]]{{spaced ndash}} around 1957.
** [[Diffusion transistor]]{{spaced ndash}} modern type bipolar junction transistor. Prototypes<ref>{{cite web |url=http://semiconductormuseum.com/PhotoGallery/PhotoGallery_Prototype_DiffusedBase.htm |title=Transistor Museum Photo Gallery Bell Labs Prototype Diffused Base Germanium Silicon Transistor |access-date=August 10, 2016}}</ref> developed at Bell Labs in 1954.
*** [[Diffused-base transistor]]{{spaced ndash}} first implementation of diffusion transistor.
*** [[Mesa transistor]]{{spaced ndash}} developed at [[Texas Instruments]] in 1957.
*** [[Planar transistor]]{{spaced ndash}} the bipolar junction transistor that made mass-produced monolithic integrated circuits possible. Developed by [[Jean Hoerni]]<ref>{{cite web |title=Transistor Museum Photo Gallery Fairchild 2N1613 Early Silicon Planar Transistor |url=http://semiconductormuseum.com/PhotoGallery/PhotoGallery_2N1613.htm |access-date=August 10, 2016 }}</ref> at [[Fairchild Semiconductor|Fairchild]] in 1959.
** Epitaxial transistor<ref>{{cite web |url=http://www.computerhistory.org/semiconductor/timeline/1960-Epitaxial.html |title=1960: Epitaxial Deposition Process Enhances Transistor Performance |publisher=Computer History Museum |access-date=June 22, 2023 }}</ref>{{spaced ndash}} a bipolar junction transistor made using vapor-phase deposition. See [[Epitaxy]]. Allows very precise control of doping levels and gradients.