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upright=1.4,
gate Candi bentar, a typical Indonesian gate that is often found on the islands of Java">Indonesia.html" ;"title="Candi bentar, a typical Indonesia">Candi bentar, a typical Indonesian gate that is often found on the islands of Java and Bali B ...
(G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch electrical signals and electrical power, power. The transistor is one of the basic building blocks of modern
electronics The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons The electron is a subatomic particle In physical sciences, subatomic particles are smaller than ...
. It is composed of
semiconductor A semiconductor material has an electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric curre ...
material, usually with at least three terminals for connection to an electronic circuit. A
voltage Voltage, electric potential difference, electric pressure or electric tension is the difference in electric potential The electric potential (also called the ''electric field potential'', potential drop, the electrostatic potential) is the ...

voltage
or
current Currents or The Current may refer to: Science and technology * Current (fluid) A current in a fluid In physics, a fluid is a substance that continually Deformation (mechanics), deforms (flows) under an applied shear stress, or external force. ...
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 are found embedded in
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of indiv ...

integrated circuit
s.
Austro-Hungarian Austria-Hungary, often referred to as the Austro-Hungarian Empire or the Dual Monarchy, was a constitutional monarchy A constitutional monarchy is a form of monarchy in which the monarch exercises authority in accordance with a writte ...

Austro-Hungarian
physicist A physicist is a scientist A scientist is a person who conducts scientific research The scientific method is an Empirical evidence, empirical method of acquiring knowledge that has characterized the development of science since at leas ...

physicist
Julius Edgar Lilienfeld Julius Edgar Lilienfeld (April 18, 1882 – August 28, 1963) was an Austro-Hungarian, and later American (where he moved in 1921) physicist and electrical engineer, who was credited with the first patent on the field-effect transistor The f ...
proposed the concept of a
field-effect transistor The field-effect transistor (FET) is a type of transistor upright=1.4, gate Candi bentar, a typical Indonesian gate that is often found on the islands of Java">Indonesia.html" ;"title="Candi bentar, a typical Indonesia">Candi bentar, ...
in 1926, but it was not possible to actually construct a working device at that time. The first working device to be built was a
point-contact transistor The point-contact transistor was the first type of transistor file:MOSFET Structure.png, upright=1.4, Metal-oxide-semiconductor field-effect transistor (MOSFET), showing Metal gate, gate (G), body (B), source (S) and drain (D) terminals. The g ...

point-contact transistor
invented in 1947 by American physicists
John Bardeen John Bardeen (; May 23, 1908 – January 30, 1991) was an American engineer Engineers, as practitioners of engineering Engineering is the use of scientific method, scientific principles to design and build machines, structures, and o ...
and
Walter Brattain Walter Houser Brattain (; February 10, 1902 – October 13, 1987) was an American physicist at who, along with fellow scientists and , invented the in December 1947. They shared the 1956 for their invention. Brattain devoted much of his life ...
while working under
William Shockley William Bradford Shockley Jr. (February 13, 1910 – August 12, 1989) was an American physicist and inventor. He was the manager of a research group at Bell Labs Nokia Bell Labs (formerly named Bell Labs Innovations (1996–2007), AT&T Bell ...
at
Bell Labs Nokia Bell Labs (formerly named Bell Labs Innovations (1996–2007), AT&T Bell Laboratories (1984–1996) and Bell Telephone Laboratories (1925–1984)) is an American industrial research and scientific development company A company, ab ...
. The three shared the 1956
Nobel Prize in Physics The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions for mankind in the field of physics. It is one of the five Nobel Prizes established by the will ...
for their achievement. The most widely used type of transistor is the
metal–oxide–semiconductor field-effect transistor 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), is a type of insulated-gate field-effect transistor that is fabricated by th ...
(MOSFET), which was invented by
Mohamed Atalla Mohamed M. Atalla ( ar, محمد عطاالله; August 4, 1924 – December 30, 2009) was an Egyptian-American engineer, physical chemist Physical chemistry is the study of macroscopic The macroscopic scale is the length scale on which ...
and
Dawon Kahng Dawon Kahng ( ko, 강대원; May 4, 1931 – May 13, 1992) was a Korean-American electrical engineer and inventor, known for his work in solid-state electronics Solid-state electronics means semiconductor A semiconductor material has an el ...

Dawon Kahng
at Bell Labs in 1959. Transistors revolutionized the field of electronics, and paved the way for smaller and cheaper
radio Radio is the technology of signaling and telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device ...

radio
s,
calculator An electronic calculator is typically a portable device used to perform s, ranging from basic to complex . The first calculator was created in the early 1960s. Pocket-sized devices became available in the 1970s, especially after the , the f ...

calculator
s, and
computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations automatically. Modern computers can perform generic sets of operations known as Computer program, programs. These ...

computer
s, among other things. Most transistors are made from very pure
silicon Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

silicon
, and some from
germanium Germanium is a chemical element with the Symbol (chemistry), symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbors silicon and tin. Pure germanium i ...

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 A bipolar junction transistor (BJT) is a type of transistor upright=1.4, gate Candi bentar, a typical Indonesian gate that is often found on the islands of Java">Indonesia.html" ;"title="Candi bentar, a typical Indonesia">Candi benta ...
devices. Compared with the
vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...
, 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. Many types of transistors are made to standardized specifications by multiple manufacturers.


History

The
thermionic in a low pressure mercury gas-discharge lamp Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas ( argon ...
triode A triode is an electronic (or ''valve'' in British English) consisting of three s inside an evacuated glass envelope: a heated or , a , and a (). Developed from 's 1906 , a partial vacuum tube that added a grid electrode to the (), the trio ...

triode
, a
vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...
invented in 1907, enabled amplified
radio Radio is the technology of signaling and telecommunication, communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device ...

radio
technology and long-distance
telephony Telephony ( ) is the field of technology involving the development, application, and deployment of telecommunication services for the purpose of electronic transmission of voice, fax, or data, between distant parties. The history of telephony is i ...
. The triode, however, was a fragile device that consumed a substantial amount of power. In 1909,
physicist A physicist is a scientist A scientist is a person who conducts scientific research The scientific method is an Empirical evidence, empirical method of acquiring knowledge that has characterized the development of science since at leas ...

physicist
William Eccles William Henry Eccles Fellow of the Royal Society, FRS (23 August 1875 – 29 April 1966) was a British physicist and a pioneer in the development of radio communication. He was born in Barrow-in-Furness, Lancashire, England. Following gradua ...
discovered the crystal diode oscillator. Austro-Hungarian physicist
Julius Edgar Lilienfeld Julius Edgar Lilienfeld (April 18, 1882 – August 28, 1963) was an Austro-Hungarian, and later American (where he moved in 1921) physicist and electrical engineer, who was credited with the first patent on the field-effect transistor The f ...
filed a patent for a
field-effect transistor The field-effect transistor (FET) is a type of transistor upright=1.4, gate Candi bentar, a typical Indonesian gate that is often found on the islands of Java">Indonesia.html" ;"title="Candi bentar, a typical Indonesia">Candi bentar, ...
(FET) in Canada in 1925, which was intended to be a solid-state replacement for the triode. Lilienfeld also filed identical patents in the United States in 1926 and 1928. However, Lilienfeld 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 A semiconductor material has an electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric curre ...
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. In 1934, German inventor
Oskar Heil Oskar Heil (20 March 1908, in Langwieden – 15 May 1994, San Mateo, California San Mateo ( ; ) is a city in San Mateo County, California San Mateo County ( ), officially the County of San Mateo, is a county (United States), county located in ...

Oskar Heil
patented a similar device in Europe.


Bipolar transistors

From November 17, 1947, to December 23, 1947,
John Bardeen John Bardeen (; May 23, 1908 – January 30, 1991) was an American engineer Engineers, as practitioners of engineering Engineering is the use of scientific method, scientific principles to design and build machines, structures, and o ...
and
Walter Brattain Walter Houser Brattain (; February 10, 1902 – October 13, 1987) was an American physicist at who, along with fellow scientists and , invented the in December 1947. They shared the 1956 for their invention. Brattain devoted much of his life ...
at
AT&T AT&T Inc. is an American multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from multiple countries * Multinational state, a s ...
's
Bell Labs Nokia Bell Labs (formerly named Bell Labs Innovations (1996–2007), AT&T Bell Laboratories (1984–1996) and Bell Telephone Laboratories (1925–1984)) is an American industrial research and scientific development company A company, ab ...
in
Murray Hill, New Jersey Murray Hill is an unincorporated community File:Entering Heinola, Minnesota.jpg, Sign at Heinola, Minnesota, Heinola, an unincorporated community in Otter Tail County, Minnesota An unincorporated area is a region not governed by a local munici ...
, performed experiments and observed that when two gold point contacts were applied to a crystal of
germanium Germanium is a chemical element with the Symbol (chemistry), symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbors silicon and tin. Pure germanium i ...

germanium
, a signal was produced with the output power greater than the input. Solid State Physics Group leader
William Shockley William Bradford Shockley Jr. (February 13, 1910 – August 12, 1989) was an American physicist and inventor. He was the manager of a research group at Bell Labs Nokia Bell Labs (formerly named Bell Labs Innovations (1996–2007), AT&T Bell ...
saw the potential in this, and over the next few months worked to greatly expand the knowledge of semiconductors. The term ''transistor'' was coined by John R. Pierce as a contraction of the term ''
transresistanceTransconductance (for transfer conductance), also infrequently called mutual electrical conductance, conductance, is the electrical characteristic relating the Electric current, current through the output of a device to the voltage across the input o ...
''. According to Lillian Hoddeson and Vicki Daitch, authors of a biography of John Bardeen, Shockley had 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 The point-contact transistor was the first type of transistor file:MOSFET Structure.png, upright=1.4, Metal-oxide-semiconductor field-effect transistor (MOSFET), showing Metal gate, gate (G), body (B), source (S) and drain (D) terminals. The g ...

point-contact transistor
. In acknowledgement of this accomplishment, Shockley, Bardeen, and Brattain were jointly awarded the 1956
Nobel Prize in Physics The Nobel Prize in Physics is a yearly award given by the Royal Swedish Academy of Sciences for those who have made the most outstanding contributions for mankind in the field of physics. It is one of the five Nobel Prizes established by the will ...
"for their researches on semiconductors and their discovery of the transistor effect". Shockley's research team initially attempted to build a field-effect transistor (FET), by trying to modulate the conductivity of a
semiconductor A semiconductor material has an electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric curre ...
, but was unsuccessful, mainly due to problems with the
surface states Surface states are electronic state Image:Energy levels.svg, Energy levels for an electron in an atom: ground state and excited states. After absorbing energy, an electron may "jump" from the ground state to a higher energy excited state. A Quantu ...
, the
dangling bondIn chemistry Chemistry is the scientific discipline involved with Chemical element, elements and chemical compound, compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo ...
, and the
germanium Germanium is a chemical element with the Symbol (chemistry), symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbors silicon and tin. Pure germanium i ...

germanium
and
copper Copper is a chemical element In chemistry, an element is a pure Chemical substance, substance consisting only of atoms that all have the same numbers of protons in their atomic nucleus, nuclei. Unlike chemical compounds, chemical elem ...

copper
compound materials. In the course of trying to understand the mysterious reasons behind their failure to build a working FET, this led them instead to invent the bipolar and junction transistors. In 1948, the point-contact transistor was independently invented by German physicists Herbert Mataré and
Heinrich Welker Heinrich Johann Welker (9 September 1912 in Ingolstadt Ingolstadt ( , , Austro-Bavarian Austro-Bavarian (also known as Austrian or Bavarian; or ; german: Bairisch ) is a West Germanic language spoken in parts of Bavaria and most of Austria. Be ...
while working at the '' Compagnie des Freins et Signaux Westinghouse'', a
Westinghouse Westinghouse may refer to: Businesses Current companies *Westinghouse Licensing, the brand management division of ViacomCBS, and licensees: **Westinghouse Electric Company, providing nuclear power related services **Westinghouse Electronics, wh ...
subsidiary located in
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,175,601 residents , in an area of more than . Since the 17th century, Paris ha ...

Paris
. Mataré had previous experience in developing crystal rectifiers from
silicon Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

silicon
and germanium in the German
radar Radar (radio detection and ranging) is a detection system that uses radio waves to determine the distance (''ranging''), angle, or velocity of objects. It can be used to detect aircraft, Marine radar, ships, spacecraft, guided missiles, motor ...

radar
effort during
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a global war A world war is "a war War is an intense armed conflict between states State may refer to: Arts, entertainment, and media Literatur ...
. Using this knowledge, he began researching the phenomenon of "interference" in 1947. By June 1948, witnessing currents flowing through point-contacts, Mataré 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 before them, the company rushed to get its "transition" into production for amplified use in France's telephone network and filed his first transistor patent application on August 13, 1948. The first
bipolar junction transistor A bipolar junction transistor (BJT) is a type of transistor upright=1.4, gate Candi bentar, a typical Indonesian gate that is often found on the islands of Java">Indonesia.html" ;"title="Candi bentar, a typical Indonesia">Candi benta ...
s were invented by Bell Labs' William Shockley, which applied for patent (2,569,347) on June 26, 1948. On April 12, 1950, Bell Labs chemists
Gordon Teal Gordon Kidd Teal (January 10, 1907 – January 7, 2003) was an American engineer. He invented a method of applying the Czochralski method The Czochralski method, also Czochralski technique or Czochralski process, is a method of crystal growth A ...
and
Morgan SparksMorgan Sparks (July 6, 1916 – May 3, 2008) was an American scientist and engineer who helped develop the microwatt bipolar junction transistor in 1951, which was a critical step in making transistors usable for every-day electronics. Sparks directe ...
had successfully produced a working bipolar NPN junction amplifying germanium transistor. Bell Labs had announced the discovery of this new "sandwich" transistor in a press release on July 4, 1951. The first high-frequency transistor was the surface-barrier germanium transistor developed by
Philco Philco (founded as Helios Electric Company, renamed Philadelphia Storage Battery Company) was a pioneer in battery, radio, and television production. In 1961 the company was purchased by Ford The Ford Motor Company, commonly known as Ford, ...
in 1953, capable of operating at frequencies up to . These 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 Indium is a chemical element upright=1.0, 500px, The chemical elements ordered by link=Periodic table In chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that c ...

Indium
electroplated into the depressions formed the collector and emitter. AT&T first used transistors in telecommunications equipment in circuits of the No. 4A Toll Crossbar Switching System in 1953 for selecting trunk circuits from routing information encoded on translator cards. The Western Electric No. 3A
phototransistor A photodiode is a semiconductor p-n junction device that converts light into an electric current, electrical current. The current is generated when photons are absorbed in the photodiode. Photodiodes may contain optical filters, built-in lenses, ...

phototransistor
read the mechanical encoding from punched metal cards. The first "prototype" pocket
transistor radio A transistor radio is a small portable radio receiver radio in the 1940s. During the golden age of radio, 1925–1955, families gathered to listen to the home radio receiver in the evening In radio, radio communications, a radio receiver, al ...

transistor radio
was shown by INTERMETALL (a company founded by Herbert Mataré in 1952) at the ''Internationale Funkausstellung Düsseldorf'' between August 29, 1953 and September 6, 1953. The first "production" pocket transistor radio was the , released in October 1954. Produced as a joint venture between the Regency Division of Industrial Development Engineering Associates, I.D.E.A. and
Texas Instruments Texas Instruments Incorporated (TI) is an America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America North America is a ...
of Dallas Texas, the TR-1 was manufactured in Indianapolis, Indiana. It was a near pocket-sized radio featuring 4 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 different colours: black, ivory, mandarin red, cloud grey, mahogany and olive green. Other colours were to shortly follow. The first "production" all-transistor car radio was developed by Chrysler and
Philco Philco (founded as Helios Electric Company, renamed Philadelphia Storage Battery Company) was a pioneer in battery, radio, and television production. In 1961 the company was purchased by Ford The Ford Motor Company, commonly known as Ford, ...
corporations and it was announced in the April 28, 1955 edition of the Wall Street Journal. Chrysler had made the all-transistor car radio, Mopar model 914HR, available as an option starting in fall 1955 for its new line of 1956 Chrysler and Imperial cars which first hit the dealership showroom floors on October 21, 1955. The
Sony , commonly known as Sony and stylized as SONY, is a Japanese multinational Multinational may refer to: * Multinational corporation, a corporate organization operating in multiple countries * Multinational force, a military body from mult ...

Sony
TR-63, released in 1957, was the first mass-produced transistor radio, leading to the mass-market penetration of transistor radios. The TR-63 went on to sell seven million units worldwide by the mid-1960s. Sony's success with transistor radios led to transistors replacing vacuum tubes as the dominant
electronic technology Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electron The electron is a subatomic particle, symbol or , whose electric charge Electric charge is the physica ...
in the late 1950s. The first working silicon transistor was developed at Bell Labs on January 26, 1954, by Morris Tanenbaum. The first commercial silicon transistor was produced by
Texas Instruments Texas Instruments Incorporated (TI) is an America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America North America is a ...
in 1954. This was the work of
Gordon Teal Gordon Kidd Teal (January 10, 1907 – January 7, 2003) was an American engineer. He invented a method of applying the Czochralski method The Czochralski method, also Czochralski technique or Czochralski process, is a method of crystal growth A ...
, an expert in growing crystals of high purity, who had previously worked at Bell Labs.


MOSFET (MOS transistor)

Semiconductor companies initially focused on junction transistors in the early years of the
semiconductor industry The semiconductor industry is the aggregate of companies engaged in the design A design is a plan or specification for the construction of an object or system or for the implementation of an activity or process, or the result of that plan or ...
. The junction transistor was a relatively bulky device that was difficult to
mass-produce Mass production, also known as flow production or continuous production, is the production of large amounts of standardized products in a constant flow, including and especially on assembly lines. Together with job production and batch product ...
, which limited it to several specialized applications.
Field-effect transistor The field-effect transistor (FET) is a type of transistor upright=1.4, gate Candi bentar, a typical Indonesian gate that is often found on the islands of Java">Indonesia.html" ;"title="Candi bentar, a typical Indonesia">Candi bentar, ...
s (FETs) were theorized as potential alternatives to junction transistors, but researchers initially could not get FETs to work properly, largely due to the troublesome
surface state Surface states are s found at the of materials. They are formed due to the sharp transition from solid material that ends with a surface and are found only at the atom layers closest to the surface. The termination of a material with a surface lea ...
barrier that prevented the external
electric field An electric field (sometimes E-field) is the physical field that surrounds electrically-charged particle In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' ' ...

electric field
from penetrating the material. In the 1950s, Egyptian engineer
Mohamed Atalla Mohamed M. Atalla ( ar, محمد عطاالله; August 4, 1924 – December 30, 2009) was an Egyptian-American engineer, physical chemist Physical chemistry is the study of macroscopic The macroscopic scale is the length scale on which ...
investigated the surface properties of
silicon Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

silicon
semiconductors at Bell Labs, where he proposed a new method of
semiconductor device fabrication Semiconductor device fabrication is the process used to manufacture semiconductor devices A semiconductor A semiconductor material has an Electrical resistivity and conductivity, electrical conductivity value falling between that of a El ...
, coating a
silicon wafer In electronics Electronics comprises the physics, engineering, technology and applications that deal with the emission, flow and control of electrons in vacuum and matter. It uses active devices to control electron flow by amplifier, amplificat ...

silicon wafer
with an insulating layer of
silicon oxideSilicon oxide may refer to either of the following: * Silicon dioxide or quartz, SiO2, very well characterized * Silicon monoxide, SiO, not very well characterized {{Short pages monitor Transistors are categorized by * Structure:
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), is a type of insulated-gate field-effect transistor that is fabricated by th ...

MOSFET
(IGFET),
BJT A bipolar junction transistor (BJT) is a type of transistor upright=1.4, gate Candi bentar, a typical Indonesian gate that is often found on the islands of Java">Indonesia.html" ;"title="Candi bentar, a typical Indonesia">Candi benta ...
,
JFET The junction-gate field-effect transistor (JFET) is one of the simplest types of field-effect transistor The field-effect transistor (FET) is a type of transistor file:MOSFET Structure.png, upright=1.4, Metal-oxide-semiconductor field-effe ...
,
insulated-gate bipolar transistor An insulated-gate bipolar transistor (IGBT) is a three-terminal power semiconductor device A power semiconductor device is a semiconductor device used as a switch or rectifier in power electronics (for example in a switch-mode power supply). Suc ...
(IGBT), other types. *
semiconductor material A semiconductor material has an electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric curre ...
(
dopant A dopant, also called a doping agent, is a trace of impurity element that is introduced into a chemical material to alter its original electrical Electricity is the set of physical phenomena associated with the presence and motion Image ...
s): ** The
metalloids A metalloid is a type of chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting only of atoms that all have th ...
;
germanium Germanium is a chemical element with the Symbol (chemistry), symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbors silicon and tin. Pure germanium i ...

germanium
(first used in 1947) and
silicon Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

silicon
(first used in 1954)—in
amorphous In condensed matter physics Condensed matter physics is the field of physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science th ...
,
polycrystalline A crystallite is a small or even microscopic crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice ...

polycrystalline
and monocrystalline form. ** The compounds
gallium arsenide Gallium Gallium is a chemical element with the Symbol (chemistry), symbol Ga and atomic number 31. Discovered by France, French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in boron group, group 13 of the periodic ta ...

gallium arsenide
(1966) and
silicon carbide Silicon carbide (SiC), also known as carborundum (), is a semiconductor containing silicon and carbon. It occurs in nature as the extremely rare mineral moissanite. Synthetic SiC powder has been mass-produced since 1893 for use as an abrasive. Gra ...

silicon carbide
(1997). ** The
alloy An alloy is an admixture of metal A metal (from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in ...
silicon-germaniumSiGe ( or ), or silicon-germanium, is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, ...
(1989) ** The
allotrope of carbon Carbon Carbon (from la, carbo "coal") is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an element is a pure substance consisting on ...
graphene Graphene () is an allotrope of carbon Carbon Carbon (from la, carbo "coal") is a chemical element Image:Simple Periodic Table Chart-blocks.svg, 400px, Periodic table, The periodic table of the chemical elements In chemistry, an ...
(research ongoing since 2004), etc. (see
Semiconductor material A semiconductor material has an electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric curre ...
). * 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 , an abbreviation for gain–bandwidth product#Transistors, transition frequency—the frequency of transition is 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, , (transistor beta) or (transconductance). * Working temperature: Extreme temperature transistors and traditional temperature transistors (). Extreme temperature transistors include high-temperature transistors (above ) and low-temperature transistors (below ). The high-temperature transistors that operate thermally stable up to can be developed by a general strategy of blending interpenetrating semi-crystalline conjugated polymers and high glass-transition temperature insulating polymers. 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 a electrical symbol) involves the direction of the arrow. For the
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, on an n-p-n transistor symbol, the arrow will "Not Point iN". On a p-n-p transistor symbol, the arrow "Points iN Proudly". This however 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)

The ''
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'', 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 () is increased, the drain–source current () increases exponentially for below threshold, and then at a roughly quadratic rate: (, where is the threshold voltage at which drain current begins) 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. 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 The junction-gate field-effect transistor (JFET) is one of the simplest types of field-effect transistor The field-effect transistor (FET) is a type of transistor file:MOSFET Structure.png, upright=1.4, Metal-oxide-semiconductor field-effe ...
) and ''insulated gate FET'' (IGFET). The IGFET is more commonly known as a ''metal–oxide–semiconductor FET'' (
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), is a type of insulated-gate field-effect transistor that is fabricated by th ...

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 A triode is an electronic (or ''valve'' in British English) consisting of three s inside an evacuated glass envelope: a heated or , a , and a (). Developed from 's 1906 , a partial vacuum tube that added a grid electrode to the (), the trio ...

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 (MESFETs) 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)

The
metal–oxide–semiconductor field-effect transistor 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), is a type of insulated-gate field-effect transistor that is fabricated by th ...
(MOSFET, MOS-FET, or MOS FET), also known as the metal–oxide–silicon transistor (MOS transistor, or MOS), is a type of field-effect transistor that is Semiconductor device fabrication, fabricated by the thermal oxidation, controlled oxidation of a
semiconductor A semiconductor material has an electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric curre ...
, typically
silicon Silicon is a chemical element with the Symbol (chemistry), symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a Tetravalence, tetravalent metalloid and semiconductor. It is a member ...

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 The field of electronics is a branch of physics and electrical engineering that deals with the emission, behaviour and effects of electrons The electron is a subatomic particle In physical sciences, subatomic particles are smaller than ...
. The MOSFET accounts for 99.9% of all transistors in the world.


Bipolar junction transistor (BJT)

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 junctions: 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 An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the power Power typically refers to: * Power (physics) In physics, power is the amount of energy transferred or converted per unit time. In ...

amplifier
s because the currents at the emitter and collector are controllable by a relatively small base current. In an n–p–n transistor operating in the active region, the emitter-base junction is forward biased (electrons 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. 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''BE) is increased the base-emitter current and hence the collector-emitter current (''I''CE) 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 A photodiode is a semiconductor p-n junction device that converts light into an electric current, electrical current. The current is generated when photons are absorbed in the photodiode. Photodiodes may contain optical filters, built-in lenses, ...

phototransistor
s.


Usage of MOSFETs and BJTs

The
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), is a type of insulated-gate field-effect transistor that is fabricated by th ...

MOSFET
is by far the most widely used transistor for both
digital circuit In theoretical computer science Theoretical computer science (TCS) is a subset of general computer science Computer science deals with the theoretical foundations of information, algorithms and the architectures of its computation as well ...
s as well as analog circuits, accounting for 99.9% of all transistors in the world. The
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(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 MOSFETs, LDMOS and RF CMOS) replaced them for most power electronic applications in the 1980s. In
integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuit 200px, A circuit built on a printed circuit board (PCB). An electronic circuit is composed of indiv ...

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

*
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(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 power electronics *** 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 nanosheets instead of nanowires, made by Samsung *** Thin-film transistor, used in Liquid-crystal display, LCD and OLED displays *** Floating-gate MOSFET (FGMOS), for non-volatile storage *** Power MOSFET, for power electronics **** LDMOS, lateral diffused MOS (LDMOS) ** Carbon nanotube field-effect transistor (CNFET), where the channel material is replaced by a carbon nanotube ** 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) ** 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). * Bipolar junction transistor (BJT): ** Heterojunction bipolar transistor, up to several hundred GHz, common in modern ultrafast and RF circuits ** Schottky transistor ** avalanche transistor ** Darlington transistors 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 transistors (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'' , intended for three-phase power supplies, houses three n–p–n IGBTs in a case measuring 38 by 140 by 190 mm and weighing 1.5 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, and abandoned a few years later around 2012. ** 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 stochastically. * 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, can be used as simple pulse generators. 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 transistors (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. * Nanofluidic transistor, controls the movement of ions through sub-microscopic, water-filled channels. * Multigate devices: ** Tetrode transistor ** Pentode transistor ** Trigate transistor (prototype by Intel) ** Dual-gate field-effect transistors 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. * 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. * Organic electrochemical transistor. * Solaristor (from solar cell transistor), a two-terminal gate-less self-powered phototransistor.


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
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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.


Japanese Industrial Standard (JIS)

In Japan, the JIS semiconductor designation (, JIS-C-7012), labels transistor devices starting with ''2S'', 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''FE (gain) groupings.


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''FE, such as in: BC549C) or other codes may follow to show gain (e.g. BC327-25) or voltage rating (e.g. BUK854-800A). The more common prefixes are:


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 Fairchild Semiconductor International, Inc. was an American semiconductor A semiconductor material has an electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental pr ...
) 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 which is also assigned the CV number: CV7763


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 junction-gate field-effect transistor (JFET) is one of the simplest types of field-effect transistor The field-effect transistor (FET) is a type of transistor file:MOSFET Structure.png, upright=1.4, Metal-oxide-semiconductor field-effe ...
, the other the higher-powered
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), is a type of insulated-gate field-effect transistor that is fabricated by th ...

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


Semiconductor material

The first BJTs were made from
germanium Germanium is a chemical element with the Symbol (chemistry), symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbors silicon and tin. Pure germanium i ...

germanium
(Ge). Silicon (Si) types currently predominate but certain advanced microwave and high-performance versions now employ the ''compound semiconductor'' material
gallium arsenide Gallium Gallium is a chemical element with the Symbol (chemistry), symbol Ga and atomic number 31. Discovered by France, French chemist Paul-Émile Lecoq de Boisbaudran in 1875, Gallium is in boron group, group 13 of the periodic ta ...

gallium arsenide
(GaAs) and the ''semiconductor alloy''
silicon-germaniumSiGe ( or ), or silicon-germanium, is an alloy An alloy is an admixture of metal A metal (from Ancient Greek, Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, ...
(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 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 mV/°C. In some circuits special compensating elements (sensistors) 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 In solid-state physics Solid-state physics is the study of rigid matter, or solids, through methods such as quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state ph ...
'' and ''hole mobility'' columns show the average speed that electrons and holes diffuse through the semiconductor material with an
electric field An electric field (sometimes E-field) is the physical field that surrounds electrically-charged particle In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' ' ...

electric field
of 1 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 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 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

Discrete transistors can be individually packaged transistors or unpackaged transistor chips (dies). Transistors come in many different semiconductor packages (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 sinks 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 shortlist 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. 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).


Flexible transistors

Researchers have made several kinds of flexible transistors, including organic field-effect transistors. Flexible transistors are useful in some kinds of flexible displays and other flexible electronics.


See also

* Band gap * Digital electronics *Diffused junction transistor * Moore's law * Optical transistor * Semiconductor device modeling * Transistor count * Transistor model * Transresistance * Very Large Scale Integration


References


Further reading

;Books * * * The invention of the transistor & the birth of the information age * * ''The Power Transistor - Temperature and Heat Transfer''; 1st Ed; John McWane, Dana Roberts, Malcom Smith; McGraw-Hill; 82 pages; 1975; . (archive)
/small> * ''Transistor Circuit Analysis - Theory and Solutions to 235 Problems''; 2nd Ed; Alfred Gronner; Simon and Schuster; 244 pages; 1970. (archive)
/small> * ''Transistor Physics and Circuits''; R.L. Riddle and M.P. Ristenbatt; Prentice-Hall; 1957. ;Periodicals * * * ;Databooks
Discrete Databook
1985; Fairchild (now ON Semiconductor)
Small-Signal Semiconductors Databook
1987; Motorola (now ON semiconductor)
Discrete Power Devices Databook
1982; SGS (now STMicroelectronics)
Discrete Databook
1978; National Semiconductor (now Texas Instruments)


External links


BBC: Building the digital age
photo history of transistors


''IEEE Global History Network, The Transistor and Portable Electronics''
All about the history of transistors and integrated circuits.
''This Month in Physics History: November 17 to December 23, 1947: Invention of the First Transistor''
From the American Physical Society
''50 Years of the Transistor''
From Science Friday, December 12, 1997 ; Pinouts
Common transistor pinouts
{{Authority control Transistors, 1947 in computing 1947 in technology 20th-century inventions American inventions Bell Labs Computer-related introductions in 1947 Electrical components Hungarian inventions Semiconductor devices