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133-434: A transistor is a semiconductor device used to amplify or switch electrical signals and power . It is one of the basic building blocks of modern electronics . It is composed of semiconductor material , usually with at least three terminals for connection to an electronic circuit . A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because

266-501: 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 tubes and Gyrotrons . Many types of transistors are made to standardized specifications by multiple manufacturers. The thermionic triode ,

399-515: A junction field-effect transistor ( JFET ) or by an electrode insulated from the bulk material by an oxide layer, forming a metal–oxide–semiconductor field-effect transistor ( MOSFET ). The metal-oxide-semiconductor FET (MOSFET, or MOS transistor), a solid-state device, is by far the most used widely semiconductor device today. It accounts for at least 99.9% of all transistors, and there have been an estimated 13   sextillion MOSFETs manufactured between 1960 and 2018. The gate electrode

532-503: A limited liability company . In a filing with the South Dakota Secretary of State dated January 30, 2024, the reason given for the merger is that New York state law does not allow AT&T Corp. to be directly converted into an LLC. Although acquired by SBC in 2005, AT&T Corp. has remained a separate entity within the corporate structure of AT&T Inc. The merger, said to create “greater operational efficiencies”, will end

665-453: A long distance subsidiary until its dissolution on May 1, 2024. AT&T started with Bell Patent Association , a legal entity established in 1874 to protect the patent rights of Alexander Graham Bell after he invented the telephone system. Originally a verbal agreement, it was formalized in writing in 1875 as Bell Telephone Company . In 1880 the management of American Bell created what would become AT&T Long Lines . The project

798-529: 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). 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,

931-470: 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 discovered the crystal diode oscillator . Physicist Julius Edgar Lilienfeld filed a patent for a field-effect transistor (FET) in Canada in 1925, intended as a solid-state replacement for

1064-520: A 171 conference room inn. The AT&T Learning Center won the commercial property known as Somerset County's Land Development Award that year. In 1992, Basking Ridge location would become a corporate headquarters just before AT&T leased the New York City, 550 Madison Avenue building to Sony in 1993. The corporate statue, known as " Golden Boy " was moved in 1992, from the former New York City headquarters to this current New Jersey headquarters. In 1992,

1197-407: A Class 1 licensed private helipad , a two-story cafeteria, a wood-burning fireplace, an indoor waterfall at the entrance lobby, and a seven-acre created lake for flood control. The entire property was 130 acre and cost $ 219 million to construct. Later, across the street from the complex, AT&T purchased additional land and established its Learning Center in 1985, at 300 North Maple Avenue, to become

1330-764: A billion individually packaged (known as discrete ) MOS transistors every year, the vast majority are produced in integrated circuits (also known as ICs , microchips, or simply chips ), along with diodes , resistors , capacitors and other electronic components , 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. 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 mechatronic circuits have replaced electromechanical devices in controlling appliances and machinery. It

1463-422: A clearly visible crack near the middle. However, as he moved about the room trying to test it, the detector would mysteriously work, and then stop again. After some study he found that the behavior was controlled by the light in the room – more light caused more conductance in the crystal. He invited several other people to see this crystal, and Walter Brattain immediately realized there was some sort of junction at

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1596-408: A continent-wide telephone system. On December 30, 1899, the assets of American Bell were transferred into its subsidiary American Telephone and Telegraph Company (formerly AT&T Long Lines ); this was because Massachusetts corporate laws were very restrictive, and limited capitalization to ten million dollars, forestalling American Bell's further growth. With this assets transfer at the very end of

1729-411: A corporate art consultant approached, artist sculptor, Elyn Zimmerman , to commission a 30-foot diameter project with fountain and seating area for the conference center courtyard gardens. In 1994, the project was completed and had one 34 ton granite boulder centered on top of the other boulders, which flowed water from the fountain designed by fountain engineer, Dr. Gerald Palevsky. AT&T occupancy at

1862-565: A device had been built. In 1934, inventor Oskar Heil patented a similar device in Europe. From November 17 to December 23, 1947, John Bardeen and Walter Brattain at 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. Solid State Physics Group leader William Shockley saw

1995-596: A few hundred milliwatts, but power and audio fidelity gradually increased as better transistors became available and amplifier architecture evolved. Modern transistor audio amplifiers of up to a few hundred watts are common and relatively inexpensive. Before transistors were developed, vacuum (electron) tubes (or in the UK "thermionic valves" or just "valves") were the main active components in electronic equipment. The key advantages that have allowed transistors to replace vacuum tubes in most applications are Transistors may have

2128-423: 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 and junction transistors . In 1948, the point-contact transistor

2261-411: A generic name for their new invention: "Semiconductor Triode", "Solid Triode", "Surface States Triode" [ sic ], "Crystal Triode" and "Iotatron" were all considered, but "transistor", coined by John R. Pierce , won an internal ballot. The rationale for the name is described in the following extract from the company's Technical Memoranda (May 28, 1948) [26] calling for votes: Transistor. This

2394-538: A headquarters on 195 Broadway (close to what is now the World Trade Center site ). The property originally belonged to Western Union , of which AT&T held a controlling interest until 1913 when AT&T divested its interest as part of the Kingsbury Commitment . Construction of the current building began in 1912. Designed by William Welles Bosworth , who played a significant role in designing Kykuit ,

2527-435: A layer of silicon dioxide over the silicon wafer, for which they observed surface passivation effects. By 1957 Frosch and Derick, using masking and predeposition, were able to manufacture silicon dioxide field effect transistors; the first planar transistors, in which drain and source were adjacent at the same surface. They showed that silicon dioxide insulated, protected silicon wafers and prevented dopants from diffusing into

2660-445: A message could pay a "toll" to AT&T and then air the message publicly. The original studio was the size of a telephone booth. The idea, however, did not take hold, because people would pay to broadcast messages only if they were sure that someone was listening. As a result, WEAF began broadcasting entertainment material, drawing amateur talent found among its employees. Opposition to AT&T's expansion into radio and an agreement with

2793-420: A new branch of quantum mechanics , which became known as surface physics , to account for the behavior. The electrons in any one piece of the crystal would migrate about due to nearby charges. Electrons in the emitters, or the "holes" in the collectors, would cluster at the surface of the crystal where they could find their opposite charge "floating around" in the air (or water). Yet they could be pushed away from

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2926-468: A new building at 550 Madison Avenue . This new AT&T Building was designed by Philip Johnson and quickly became an icon of the new Postmodern architectural style. The building was completed in 1984, the very year of the divestiture of the Bell System. The building proved to be too large for the post-divestiture corporation and in 1993, AT&T leased the building to Sony , who then subsequently owned

3059-410: 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. The base resistor value is calculated from the supply voltage, transistor C-E junction voltage drop, collector current, and amplification factor beta. The common-emitter amplifier is designed so that

3192-606: A sale-leaseback agreement valued at $ 650.3 million on the complex with the address previously known as One Verizon Way. In 2017, the 35 acre hotel/conference center was known as the Dolce Basking Ridge Hotel and sold for $ 30 million. On February 15, 2024, AT&T Inc. filed notice with the Kentucky Public Service Commission that it intends to make an internal structural change and merge AT&T Corp. into AT&T Enterprises, Inc., which will become

3325-549: A single larger surface would serve. The electron-emitting and collecting leads would both be placed very close together on the top, with the control lead placed on the base of the crystal. When current flowed through this "base" lead, the electrons or holes would be pushed out, across the block of the semiconductor, and collect on the far surface. As long as the emitter and collector were very close together, this should allow enough electrons or holes between them to allow conduction to start. The Bell team made many attempts to build such

3458-604: A small change in voltage ( V in ) 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 in produce large changes in V out . Various configurations of single transistor amplifiers are possible, with some providing current gain, some voltage gain, and some both. From mobile phones to televisions , vast numbers of products include amplifiers for sound reproduction , radio transmission , and signal processing . The first discrete-transistor audio amplifiers barely supplied

3591-503: A subset of devices follow those. For discrete devices , for example, there are three standards: JEDEC JESD370B in the United States, Pro Electron in Europe, and Japanese Industrial Standards (JIS). Semiconductor device fabrication is the process used to manufacture semiconductor devices , typically integrated circuits (ICs) such as computer processors , microcontrollers , and memory chips (such as RAM and Flash memory ). It

3724-449: A system with various tools but generally failed. Setups, where the contacts were close enough, were invariably as fragile as the original cat's whisker detectors had been, and would work briefly, if at all. Eventually, they had a practical breakthrough. A piece of gold foil was glued to the edge of a plastic wedge, and then the foil was sliced with a razor at the tip of the triangle. The result was two very closely spaced contacts of gold. When

3857-658: A very small current can be achieved when the diode is reverse biased (connected with the n-side at lower electric potential than the p-side, and thus the depletion region expanded). Exposing a semiconductor to light can generate electron–hole pairs , which increases the number of free carriers and thereby the conductivity. Diodes optimized to take advantage of this phenomenon are known as photodiodes . Compound semiconductor diodes can also produce light, as in light-emitting diodes and laser diode Bipolar junction transistors (BJTs) are formed from two p–n junctions, in either n–p–n or p–n–p configuration. The middle, or base ,

3990-415: 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. There are two types of transistors, with slight differences in how they are used: The top image in this section represents a typical bipolar transistor in a circuit. A charge flows between emitter and collector terminals depending on

4123-529: A working MOS device with their Bell Labs team in 1960. Their team included E. E. LaBate and E. I. Povilonis who fabricated the device; M. O. Thurston, L. A. D’Asaro, and J. R. Ligenza who developed the diffusion processes, and H. K. Gummel and R. Lindner who characterized the device. With its high scalability , much lower power consumption, and higher density than bipolar junction transistors, the MOSFET made it possible to build high-density integrated circuits, allowing

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4256-458: 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. The first high-frequency transistor was the surface-barrier germanium transistor developed by Philco in 1953, capable of operating at frequencies up to 60 MHz . They were made by etching depressions into an n-type germanium base from both sides with jets of indium(III) sulfate until it

4389-437: Is a device typically made from a single p–n junction . At the junction of a p-type and an n-type semiconductor , there forms a depletion region where current conduction is inhibited by the lack of mobile charge carriers. When the device is forward biased (connected with the p-side, having a higher electric potential than the n-side), this depletion region is diminished, allowing for significant conduction. Contrariwise, only

4522-429: Is a multiple-step photolithographic and physico-chemical process (with steps such as thermal oxidation , thin-film deposition, ion-implantation, etching) during which electronic circuits are gradually created on a wafer , typically made of pure single-crystal semiconducting material. Silicon is almost always used, but various compound semiconductors are used for specialized applications. The fabrication process

4655-574: Is also gaining popularity in power ICs and has found some application as the raw material for blue LEDs and is being investigated for use in semiconductor devices that could withstand very high operating temperatures and environments with the presence of significant levels of ionizing radiation . IMPATT diodes have also been fabricated from SiC. Various indium compounds ( indium arsenide , indium antimonide , and indium phosphide ) are also being used in LEDs and solid-state laser diodes . Selenium sulfide

4788-491: Is an abbreviated combination of the words "transconductance" or "transfer", and "varistor". The device logically belongs in the varistor family, and has the transconductance or transfer impedance of a device having gain, so that this combination is descriptive. Shockley was upset about the device being credited to Brattain and Bardeen, who he felt had built it "behind his back" to take the glory. Matters became worse when Bell Labs lawyers found that some of Shockley's own writings on

4921-449: Is being studied in the manufacture of photovoltaic solar cells . The most common use for organic semiconductors is organic light-emitting diodes . All transistor types can be used as the building blocks of logic gates , which are fundamental in the design of digital circuits . In digital circuits like microprocessors , transistors act as on-off switches; in the MOSFET , for instance,

5054-608: Is called a "hypostyle hall", with full-bodied Doric columns modeled on the Parthenon, marking out a grid. Bosworth was seeking to coordinate the classical tradition with the requirements of a modern building. Columns were not merely the decorative elements they had become in the hands of other architects but created all the illusion of being real supports. Bosworth also designed the campus of MIT as well as Theodore N. Vail 's mansion in Morristown, New Jersey . In 1978, AT&T commissioned

5187-502: Is charged to produce an electric field that controls the conductivity of a "channel" between two terminals, called the source and drain . Depending on the type of carrier in the channel, the device may be an n-channel (for electrons) or a p-channel (for holes) MOSFET. Although the MOSFET is named in part for its "metal" gate, in modern devices polysilicon is typically used instead. Two-terminal devices: Three-terminal devices: Four-terminal devices: By far, silicon (Si)

5320-480: Is not observed in modern devices, for example, at the 65 nm technology node. For low noise at narrow 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,

5453-421: 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. 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 . It can produce a stronger output signal, a voltage or current, proportional to

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5586-446: Is performed in highly specialized semiconductor fabrication plants , also called foundries or "fabs", with the central part being the " clean room ". In more advanced semiconductor devices, such as modern 14 / 10 / 7 nm nodes, fabrication can take up to 15 weeks, with 11–13 weeks being the industry average. Production in advanced fabrication facilities is completely automated, with automated material handling systems taking care of

5719-439: Is the most widely used material in semiconductor devices. Its combination of low raw material cost, relatively simple processing, and a useful temperature range makes it currently the best compromise among the various competing materials. Silicon used in semiconductor device manufacturing is currently fabricated into boules that are large enough in diameter to allow the production of 300 mm (12 in.) wafers . Germanium (Ge)

5852-540: The American Telephone and Telegraph Company , was an American telecommunications company that provided voice, video, data, and Internet telecommunications and professional services to businesses, consumers, and government agencies. During the Bell System 's long history, AT&T was at times the world's largest telephone company, the world's largest cable television operator, and a regulated monopoly. At its peak in

5985-493: The National Broadcasting Company to lease long-distance lines for their broadcasts resulted in the sale of the station and its developing network of affiliates to NBC. On April 30, 1907, Theodore Newton Vail became President of AT&T. Vail believed in the superiority of one phone system and AT&T adopted the slogan "One Policy, One System, Universal Service." This would be the company's philosophy for

6118-440: The self-aligned gate (silicon-gate) MOS transistor, which Fairchild Semiconductor researchers Federico Faggin and Tom Klein used to develop the first silicon-gate MOS integrated circuit . A double-gate MOSFET was first demonstrated in 1984 by Electrotechnical Laboratory researchers Toshihiro Sekigawa and Yutaka Hayashi. The FinFET (fin field-effect transistor), a type of 3D non-planar multi-gate MOSFET, originated from

6251-469: The surface state barrier that prevented the external electric field from penetrating the material. In 1955, Carl Frosch and Lincoln Derick accidentally grew a layer of silicon dioxide over the silicon wafer, for which they observed surface passivation effects. By 1957 Frosch and Derick, using masking and predeposition, were able to manufacture silicon dioxide field effect transistors; the first planar transistors, in which drain and source were adjacent at

6384-928: The voltage applied to the gate determines whether the switch is on or off. Transistors used for analog circuits do not act as on-off switches; rather, they respond to a continuous range of inputs with a continuous range of outputs. Common analog circuits include amplifiers and oscillators . Circuits that interface or translate between digital circuits and analog circuits are known as mixed-signal circuits . Power semiconductor devices are discrete devices or integrated circuits intended for high current or high voltage applications. Power integrated circuits combine IC technology with power semiconductor technology, these are sometimes referred to as "smart" power devices. Several companies specialize in manufacturing power semiconductors. The part numbers of semiconductor devices are often manufacturer specific. Nevertheless, there have been attempts at creating standards for type codes, and

6517-484: The 1950s and 1960s, it employed one million people and its revenue ranged between US$ 3 billion in 1950 ($ 41.3 billion in present-day terms ) and $ 12 billion in 1966 ($ 117 billion in present-day terms ). In 2005, AT&T was acquired by " Baby Bell " and former subsidiary SBC Communications for more than $ 16 billion ($ 25 billion in present-day terms ). SBC then changed its name to AT&T Inc. , with AT&T Corporation continuing to exist as

6650-492: The 19th century, AT&T became the parent of both American Bell and the Bell System . AT&T was involved mainly in the telephone business and, although it was a partner with RCA , was reluctant to see radio grow because such growth might diminish the demand for wired services. It established station WEAF in New York as what was termed a toll station . AT&T could provide no programming, but anyone who wished to broadcast

6783-536: The EFEM which helps reduce the amount of humidity that enters the FOUP and improves yield. Semiconductors had been used in the electronics field for some time before the invention of the transistor. Around the turn of the 20th century they were quite common as detectors in radios , used in a device called a "cat's whisker" developed by Jagadish Chandra Bose and others. These detectors were somewhat troublesome, however, requiring

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6916-449: The FOUPs into the machine. Additionally many machines also handle wafers in clean nitrogen or vacuum environments to reduce contamination and improve process control. Fabrication plants need large amounts of liquid nitrogen to maintain the atmosphere inside production machinery and FOUPs, which are constantly purged with nitrogen. There can also be an air curtain or a mesh between the FOUP and

7049-659: 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 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. Semiconductor device Semiconductor devices are manufactured both as single discrete devices and as integrated circuits , which consist of two or more devices—which can number from

7182-404: The MOSFET in 1959. The MOSFET is by far the most widely used transistor, in applications ranging from computers and electronics to communications technology such as smartphones . It has been considered the most important transistor, possibly the most important invention in electronics, and the device that enabled modern electronics. It has been the basis of modern digital electronics since

7315-421: The MOSFET was invented at Bell Labs between 1955 and 1960. Transistors revolutionized the field of electronics and paved the way for smaller and cheaper radios , calculators , computers , 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

7448-520: The Rockefeller mansion north of Tarrytown, New York , it was a modern steel structure clad top to bottom in a Greek-styled exterior, the three-story-high Ionic columns of Vermont granite forming eight registers over a Doric base. The lobby of the AT&;T Building was one of the most unusual ones of the era. Instead of a large double-high space, similar to the nearby Woolworth Building , Bosworth designed what

7581-568: 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. The first production all-transistor car radio

7714-689: The United States and Canada through a network of companies called the Bell System . At this time, the company was nicknamed Ma Bell . AT&T had a domestic and global presence in laying the infrastructure of undersea routes for telecommunications. In 1950, the U.S. Navy commissioned a network of undersea surveillance cables for foreign submarine detection. AT&T was probably, according to internal employees, involved in this Sound Surveillance System ( SOSUS ). After completion, AT&T began commercial operations in cable laying for communications in 1955. The implementation of cables assured local and long-distance telephone or data services would provide revenue for

7847-412: The base-emitter current. Another type of transistor, the field-effect transistor (FET), operates on the principle that semiconductor conductivity can be increased or decreased by the presence of an electric field . An electric field can increase the number of free electrons and holes in a semiconductor, thereby changing its conductivity. The field may be applied by a reverse-biased p–n junction, forming

7980-404: 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

8113-588: The building until it was sold in 2013. In 1969, AT&T began plans to construct an administration corporate complex in the suburbs. In early 1970, AT&T began purchases of land in the suburbs of New Jersey for this office complex and began construction in 1974. The award-winning architect, Vincent Kling , designed a Fordism style, luxurious "Pagoda" campus layout and the construction firms: New York–based Walter Kidde and Newark, New Jersey –based Frank Briscoe, managed this joint venture construction project with Vollers Construction of Branchburg, New Jersey , as

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8246-436: 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 . The use of bipolar transistors for switching applications requires biasing

8379-528: The company. AT&T Long Lines was one of the divisions responsible for the cable-laying and maintaining of Long Lines' undersea cables. Western Electric was the manufacturing company responsible for production and supply of undersea coaxial equipment and later, fiber cables. Equipment such as repeaters was manufactured in Clark, New Jersey and coaxial cable was manufactured in Baltimore, Maryland . Also, Bell Labs

8512-514: The concept of a field-effect transistor (FET) in 1926, but it was not possible to construct a working device at that time. The first working device was a point-contact transistor invented in 1947 by physicists John Bardeen , Walter Brattain , and William Shockley at Bell Labs who shared the 1956 Nobel Prize in Physics for their achievement. The most widely used type of transistor is the metal–oxide–semiconductor field-effect transistor (MOSFET),

8645-444: The concept of an inversion layer, forms the basis of CMOS and DRAM technology today. In the early years of the semiconductor industry , companies focused on the junction transistor , a relatively bulky device that was difficult to mass-produce , limiting it to several specialized applications. Field-effect transistors (FETs) were theorized as potential alternatives, but researchers could not get them to work properly, largely due to

8778-448: 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 circuits . Because transistors are the key active components in practically all modern electronics , many people consider them one of the 20th century's greatest inventions. Physicist Julius Edgar Lilienfeld proposed

8911-560: The corporate logo designed by Saul Bass in 1983 and originally used by AT&T Information Systems , was created because part of the United States v. AT&T settlement required AT&T to relinquish all claims to the use of Bell System trademarks. It has been nicknamed the " Death Star " in reference to the Death Star space station in Star Wars which the logo resembles. In 1999 it

9044-446: The crack. Further research cleared up the remaining mystery. The crystal had cracked because either side contained very slightly different amounts of the impurities Ohl could not remove – about 0.2%. One side of the crystal had impurities that added extra electrons (the carriers of electric current) and made it a "conductor". The other had impurities that wanted to bind to these electrons, making it (what he called) an "insulator". Because

9177-424: The crystal were of any reasonable size, the number of electrons (or holes) required to be injected would have to be very large, making it less than useful as an amplifier because it would require a large injection current to start with. That said, the whole idea of the crystal diode was that the crystal itself could provide the electrons over a very small distance, the depletion region. The key appeared to be to place

9310-558: 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 BE . (Base Emitter Voltage) Transistors are commonly used in digital circuits as electronic switches which can be either in an "on" or "off" state, both for high-power applications such as switched-mode power supplies and for low-power applications such as logic gates . Important parameters for this application include

9443-455: The current switched, the voltage handled, and the switching speed, characterized by the rise and fall times . 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,

9576-458: The drain and source is controlled by the voltage applied between the gate and source. As the gate–source voltage ( V GS ) is increased, the drain–source current ( I DS ) increases exponentially for V GS below threshold, and then at a roughly quadratic rate: ( I DS ∝ ( V GS − V T ) , where V T is the threshold voltage at which drain current begins) in the " space-charge-limited " region above threshold. A quadratic behavior

9709-399: The electrons being pushed into the collector would quickly fill up the "holes" (the electron-needy impurities), and conduction would stop almost instantly. This junction of the two crystals (or parts of one crystal) created a solid-state diode, and the concept soon became known as semiconduction. The mechanism of action when the diode off has to do with the separation of charge carriers around

9842-410: The electrons from the emitter to the collector of this newly discovered diode, an amplifier could be built. For instance, if contacts are placed on both sides of a single type of crystal, current will not flow between them through the crystal. However, if a third contact could then "inject" electrons or holes into the material, the current would flow. Actually doing this appeared to be very difficult. If

9975-627: The existence of the nearly 140-year-old entity. The internal merger took effect on May 1, 2024. AT&T, prior to its merger with SBC Communications , had three core companies: AT&T Alascom sold service in Alaska. AT&T Communications was renamed AT&T Communications – East, Inc. and sold long-distance telephone service and operated as a CLEC outside of the borders of the Bell Operating Companies that AT&T owned. It has now been absorbed into AT&T Corp. and all but 4 of

10108-450: The first demonstration to higher-ups at Bell Labs on the afternoon of 23 December 1947, often given as the birthdate of the transistor. What is now known as the " p–n–p point-contact germanium transistor " operated as a speech amplifier with a power gain of 18 in that trial. John Bardeen , Walter Houser Brattain , and William Bradford Shockley were awarded the 1956 Nobel Prize in physics for their work. Bell Telephone Laboratories needed

10241-495: The following Monday, November 21 as " the new AT&T " and began trading under the "T" symbol on December 1. Present-day AT&T Inc. claims AT&T Corp.'s history as its own, but retains SBC's pre-2005 stock price history and corporate structure. As well, all SEC filings before 2005 are under SBC, not AT&T. From 1885 to 1910, AT&T was headquartered at 125 Milk Street in Boston. With its expansion it moved to New York City, to

10374-451: The following limitations: Transistors are categorized by Hence, a particular transistor may be described as silicon, surface-mount, BJT, NPN, low-power, high-frequency switch . Convenient mnemonic to remember the type of transistor (represented by an electrical symbol ) involves the direction of the arrow. For the BJT , on an n-p-n transistor symbol, the arrow will " N ot P oint i N" . On

10507-505: The former complex, excluding the hotel/conference room building, from Pfizer for Verizon Wireless Headquarters and consolidation of employees from Manhattan as well as other nearby New Jersey building locations. In 2007, Pfizer placed the North Maple Inn for sale. At the time, it was a four-diamond, certified hotel and conference center under IACC ("International Association of Conference Centers") designation. In 2015, Verizon performed

10640-480: The former parent company's main business was now AT&T Communications Inc. , which focused on long-distance services, and with other non-RBOC activities. AT&T acquired NCR Corporation in 1991. AT&T announced in 1995 that it would split into three companies: a manufacturing/R&D company, a computer company, and a services company. NCR , Bell Labs and AT&T Technologies were to be spun off by 1997. In preparation for its spin-off, AT&T Technologies

10773-458: The government reached an agreement that allowed AT&T to continue operating as a telephone monopoly, subject to certain conditions, including divesting its interest in Western Union. While AT&T periodically faced scrutiny from regulators, this state of affairs continued until the company's breakup in 1984. Throughout most of the 20th century, AT&T held a semi-monopoly on phone service in

10906-407: The hundreds to the billions—manufactured and interconnected on a single semiconductor wafer (also called a substrate). Semiconductor materials are useful because their behavior can be easily manipulated by the deliberate addition of impurities, known as doping . Semiconductor conductivity can be controlled by the introduction of an electric or magnetic field, by exposure to light or heat, or by

11039-447: 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 . 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". Shockley's team initially attempted to build

11172-439: The input and output contacts very close together on the surface of the crystal on either side of this region. Brattain started working on building such a device, and tantalizing hints of amplification continued to appear as the team worked on the problem. Sometimes the system would work but then stop working unexpectedly. In one instance a non-working system started working when placed in water. Ohl and Brattain eventually developed

11305-465: The integration of more than 10,000 transistors in a single IC. Bardeen and Brattain's 1948 inversion layer concept forms the basis of CMOS technology today. The CMOS (complementary MOS ) was invented by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963. The first report of a floating-gate MOSFET was made by Dawon Kahng and Simon Sze in 1967. In 1967, Bell Labs researchers Robert Kerwin, Donald Klein and John Sarace developed

11438-490: The junction. This is called a " depletion region ". Armed with the knowledge of how these new diodes worked, a vigorous effort began to learn how to build them on demand. Teams at Purdue University , Bell Labs , MIT , and the University of Chicago all joined forces to build better crystals. Within a year germanium production had been perfected to the point where military-grade diodes were being used in most radar sets. After

11571-544: The labs had one. After hunting one down at a used radio store in Manhattan , he found that it worked much better than tube-based systems. Ohl investigated why the cat's whisker functioned so well. He spent most of 1939 trying to grow more pure versions of the crystals. He soon found that with higher-quality crystals their finicky behavior went away, but so did their ability to operate as a radio detector. One day he found one of his purest crystals nevertheless worked well, and it had

11704-540: The late 20th century, paving the way for the digital age . The US Patent and Trademark Office calls it a "groundbreaking invention that transformed life and culture around the world". Its ability to be 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. Although several companies each produce over

11837-512: The laying or repair of cabling under the subsidiary, Transoceanic Cable Ship Company. After the break-up, AT&T operated their ships under a subsidiary called AT&T Submarine Systems Inc, based in Morristown, New Jersey, until they sold six ships to Tyco International Ltd in 1997 for $ 850 million. AT&T continued to maintain their communication building facilities. Here is a list of the cable laying-ship fleet: Between 1951 and 2000, AT&T

11970-594: The location peaked to 6,000 employees in its heyday before AT&T experienced competition and downsizing. In October 2001, the Basking Ridge property was 140 acre with 2.6 million square feet and was placed for sale. Basking Ridge employee occupancy, prior to the sale were approximately 3,200 employees. In April 2002, Pharmacia Corporation purchased the complex for $ 210 million for their corporate headquarters from existing Peapack-Gladstone, New Jersey headquarters. A short time afterwards, in 2005, Verizon purchased

12103-428: The mechanical deformation of a doped monocrystalline silicon grid; thus, semiconductors can make excellent sensors. Current conduction in a semiconductor occurs due to mobile or "free" electrons and electron holes , collectively known as charge carriers . Doping a semiconductor with a small proportion of an atomic impurity, such as phosphorus or boron , greatly increases the number of free electrons or holes within

12236-764: 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 Düsseldorf from August 29 to September 6, 1953. The first production-model pocket transistor radio was the Regency TR-1 , 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 of Dallas, Texas,

12369-564: The more reliable and amplified vacuum tube based radios, the cat's whisker systems quickly disappeared. The "cat's whisker" is a primitive example of a special type of diode still popular today, called a Schottky diode . Another early type of semiconductor device is the metal rectifier in which the semiconductor is copper oxide or selenium . Westinghouse Electric (1886) was a major manufacturer of these rectifiers. During World War II, radar research quickly pushed radar receivers to operate at ever higher frequencies about 4000 MHz and

12502-470: The next 70 years. Under Vail, AT&T began buying up many of the smaller telephone companies including Western Union telegraph . These actions brought unwanted attention from antitrust regulators. Anxious to avoid action from government antitrust suits, AT&T and the federal government entered into an agreement known as the Kingsbury Commitment . In the Kingsbury Commitment, AT&T and

12635-399: The operator to move a small tungsten filament (the whisker) around the surface of a galena (lead sulfide) or carborundum (silicon carbide) crystal until it suddenly started working. Then, over a period of a few hours or days, the cat's whisker would slowly stop working and the process would have to be repeated. At the time their operation was completely mysterious. After the introduction of

12768-410: The original 22 subsidiaries that formed AT&T Communications continue to exist. AT&T Laboratories has been integrated into AT&T Labs , formerly named SBC Laboratories . AT&T was also known as "Ma Bell" and affectionately called "Mother" by phone phreaks . During some strikes by its employees, picketers would wear T-shirts reading, "Ma Bell is a real mother." Before the break-up, there

12901-545: 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 transresistance . 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

13034-439: The region between the junctions is typically very narrow. The other regions, and their associated terminals, are known as the emitter and the collector . A small current injected through the junction between the base and the emitter changes the properties of the base-collector junction so that it can conduct current even though it is reverse biased. This creates a much larger current between the collector and emitter, controlled by

13167-431: The research of Digh Hisamoto and his team at Hitachi Central Research Laboratory in 1989. Because transistors are the key active components in practically all modern electronics , many people consider them one of the 20th century's greatest inventions. The invention of the first transistor at Bell Labs was named an IEEE Milestone in 2009. Other Milestones include the inventions of the junction transistor in 1948 and

13300-404: 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. 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

13433-447: The same surface. They showed that silicon dioxide insulated, protected silicon wafers and prevented dopants from diffusing into the wafer. After this, J.R. Ligenza and W.G. Spitzer studied the mechanism of thermally grown oxides, fabricated a high quality Si/ SiO 2 stack and published their results in 1960. Following this research, Mohamed Atalla and Dawon Kahng proposed a silicon MOS transistor in 1959 and successfully demonstrated

13566-546: The semiconductor. When a doped semiconductor contains excess holes, it is called a p-type semiconductor ( p for positive electric charge ); when it contains excess free electrons, it is called an n-type semiconductor ( n for a negative electric charge). A majority of mobile charge carriers have negative charges. The manufacture of semiconductors controls precisely the location and concentration of p- and n-type dopants. The connection of n-type and p-type semiconductors form p–n junctions . The most common semiconductor device in

13699-649: The specification and inspection of non Bell System cable for networks such as the TAT-2 . By the continuous undersea network installations, AT&T was a globally technology leader with the 1970 installed TAT-5 and the 1975 installed TAT-6 , achieving 720 channels and then 4000 channels for transmitting voice or data. Prior to 1963, AT&T had to charter oceanic ships, such as the CS Monarch (1945) for installations. AT&T purchased CS Long Lines in 1961 and operated it with several cable laying ships that would provide, either

13832-522: The subcontractor. The 295 North Maple Avenue and Interstate 287 location of Basking Ridge in Bernards Township , New Jersey was completed in 1975 for the AT&T General Department offices. Employees began moving, in November 1975, to the seven inter-connected building complex using 28 acre of the property. The property had a 15-acre underground parking garage with spaces for 3,900 vehicles, and included

13965-426: The surface with the application of a small amount of charge from any other location on the crystal. Instead of needing a large supply of injected electrons, a very small number in the right place on the crystal would accomplish the same thing. Their understanding solved the problem of needing a very small control area to some degree. Instead of needing two separate semiconductors connected by a common, but tiny, region,

14098-467: The traditional tube-based radio receivers no longer worked well. The introduction of the cavity magnetron from Britain to the United States in 1940 during the Tizard Mission resulted in a pressing need for a practical high-frequency amplifier. On a whim, Russell Ohl of Bell Laboratories decided to try a cat's whisker . By this point, they had not been in use for a number of years, and no one at

14231-409: 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

14364-438: The transistor were close enough to those of an earlier 1925 patent by Julius Edgar Lilienfeld that they thought it best that his name be left off the patent application. Shockley was incensed, and decided to demonstrate who was the real brains of the operation. A few months later he invented an entirely new, considerably more robust, bipolar junction transistor type of transistor with a layer or 'sandwich' structure, used for

14497-476: 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. The first bipolar junction transistors 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

14630-559: The transport of wafers from machine to machine. A wafer often has several integrated circuits which are called dies as they are pieces diced from a single wafer. Individual dies are separated from a finished wafer in a process called die singulation , also called wafer dicing. The dies can then undergo further assembly and packaging. Within fabrication plants, the wafers are transported inside special sealed plastic boxes called FOUPs . FOUPs in many fabs contain an internal nitrogen atmosphere which helps prevent copper from oxidizing on

14763-418: The triode. He filed identical patents in the United States in 1926 and 1928. 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

14896-407: The two parts of the crystal were in contact with each other, the electrons could be pushed out of the conductive side which had extra electrons (soon to be known as the emitter ), and replaced by new ones being provided (from a battery, for instance) where they would flow into the insulating portion and be collected by the whisker filament (named the collector ). However, when the voltage was reversed

15029-506: The vast majority of all transistors into the 1960s. With the fragility problems solved, the remaining problem was purity. Making germanium of the required purity was proving to be a serious problem and limited the yield of transistors that actually worked from a given batch of material. Germanium's sensitivity to temperature also limited its usefulness. Scientists theorized that silicon would be easier to fabricate, but few investigated this possibility. Former Bell Labs scientist Gordon K. Teal

15162-588: The wafer diameter to sizes significantly smaller than silicon wafers thus making mass production of GaAs devices significantly more expensive than silicon. Gallium Nitride (GaN) is gaining popularity in high-power applications including power ICs , light-emitting diodes (LEDs), and RF components due to its high strength and thermal conductivity. Compared to silicon, GaN's band gap is more than 3 times wider at 3.4 eV and it conducts electrons 1,000 times more efficiently. Other less common materials are also in use or under investigation. Silicon carbide (SiC)

15295-614: The wafer. At Bell Labs, the importance of Frosch and Derick technique and transistors was immediately realized. Results of their work circulated around Bell Labs in the form of BTL memos before being published in 1957. At Shockley Semiconductor , Shockley had circulated the preprint of their article in December 1956 to all his senior staff, including Jean Hoerni , who would later invent the planar process in 1959 while at Fairchild Semiconductor . AT%26T Corporation AT&T Corporation , an abbreviation for its former name,

15428-442: The wafers. Copper is used in modern semiconductors for wiring. The insides of the processing equipment and FOUPs is kept cleaner than the surrounding air in the cleanroom. This internal atmosphere is known as a mini-environment and helps improve yield which is the amount of working devices on a wafer. This mini environment is within an EFEM (equipment front end module) which allows a machine to receive FOUPs, and introduces wafers from

15561-406: The war, William Shockley decided to attempt the building of a triode -like semiconductor device. He secured funding and lab space, and went to work on the problem with Brattain and John Bardeen . The key to the development of the transistor was the further understanding of the process of the electron mobility in a semiconductor. It was realized that if there were some way to control the flow of

15694-408: The wedge was pushed down onto the surface of a crystal and voltage was applied to the other side (on the base of the crystal), current started to flow from one contact to the other as the base voltage pushed the electrons away from the base towards the other side near the contacts. The point-contact transistor had been invented. While the device was constructed a week earlier, Brattain's notes describe

15827-405: The widespread adoption of transistor radios. Seven million TR-63s were sold worldwide by the mid-1960s. Sony's success with transistor radios led to transistors replacing vacuum tubes as the dominant electronic technology in the late 1950s. The first working silicon transistor was developed at Bell Labs on January 26, 1954, by Morris Tanenbaum . The first production commercial silicon transistor

15960-476: The world is the MOSFET (metal–oxide–semiconductor field-effect transistor ), also called the MOS transistor . As of 2013, billions of MOS transistors are manufactured every day. Semiconductor devices made per year have been growing by 9.1% on average since 1978, and shipments in 2018 are predicted for the first time to exceed 1 trillion, meaning that well over 7 trillion have been made to date. A semiconductor diode

16093-510: Was a few ten-thousandths of an inch thick. Indium electroplated into the depressions formed the collector and emitter. AT&T first used transistors in telecommunications equipment in the No. 4A Toll Crossbar Switching System in 1953, for selecting trunk circuits from routing information encoded on translator cards. Its predecessor, the Western Electric No. 3A phototransistor , read

16226-401: Was a widely used early semiconductor material but its thermal sensitivity makes it less useful than silicon. Today, germanium is often alloyed with silicon for use in very-high-speed SiGe devices; IBM is a major producer of such devices. Gallium arsenide (GaAs) is also widely used in high-speed devices but so far, it has been difficult to form large-diameter boules of this material, limiting

16359-478: 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. 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. The FET concept

16492-511: 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. The Sony TR-63, released in 1957, was the first mass-produced transistor radio, leading to

16625-503: Was greater consumer recognition of the "Bell System" name, in comparison to the name AT&T. This prompted the company to launch an advertising campaign after the break-up to increase its name recognition. Spinoffs like the Regional Bell Operating Companies or RBOC s were often called "Baby Bells". Ironically, "Ma Bell" was acquired by one of its "Baby Bells", SBC Communications , in 2005. The AT&T Globe Symbol,

16758-849: Was independently invented by physicists Herbert Mataré and Heinrich Welker while working at the Compagnie des Freins et Signaux Westinghouse , a Westinghouse subsidiary in Paris . Mataré had previous experience in developing 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

16891-453: 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 . Following Shockley's theoretical treatment on JFET in 1952, a working practical JFET was made in 1953 by George C. Dacey and Ian M. Ross . In 1948, Bardeen and Brattain patented the progenitor of MOSFET at Bell Labs, an insulated-gate FET (IGFET) with an inversion layer. Bardeen's patent, and

17024-453: Was listed 73 times in cable laying operations for specific routes deployed. The Cable Ship Long Lines had 23 cable runs from 1963 to 1992, with the first deep-sea trial of optical fiber cable in 1982 leading to the consortium of countries and locations for the TAT-8 fiber cable implementation of 1988. The United States Justice Department opened the case United States v. AT&T in 1974. This

17157-400: Was prompted by suspicion that AT&T was using monopoly profits from its Western Electric subsidiary to subsidize the cost of its network, a violation of antitrust law. A settlement to this case was finalized in 1982, leading to the division of the company on January 1, 1984, into seven Regional Bell Operating Companies , commonly known as Baby Bells. These companies were: Post-breakup,

17290-491: Was renamed Lucent Technologies . Lucent was completely spun off from AT&T in 1996. On January 31, 2005, the " Baby Bell " company SBC Communications announced its plans to acquire " Ma Bell " AT&T Corp. for $ 16 billion. SBC announced in October 2005 that it would shed the "SBC" brand and take the more recognizable AT&T brand, along with the old AT&T's "T" NYSE ticker symbol. Merger approval concluded on November 18, 2005; SBC Communications began rebranding

17423-536: Was responsible for the innovations of products or technologies in cabling in transmission by undersea systems. In 1955, the first trans-Atlantic telephone undersea cable, TAT-1 , from North America to Europe was installed by AT&T. This installation allowed 48 telephone circuits to be used for long-distance calling. When partnering with other global Telecommunications companies, such as the French Cables de Lyon and German Felten & Guilleaume , Bell Labs provided

17556-466: Was the first of its kind to create a nationwide long-distance network with a commercially viable cost-structure. The project was formally incorporated in New York as a separate company named American Telephone and Telegraph Company on March 3, 1885. Originating in New York City, its long-distance telephone network reached Chicago, Illinois , in 1892, with its multitudes of local exchanges continuing to stretch further and further yearly, eventually creating

17689-478: Was the first to develop a working silicon transistor at the nascent Texas Instruments , giving it a technological edge. From the late 1950s, most transistors were silicon-based. Within a few years transistor-based products, most notably easily portable radios, were appearing on the market. " Zone melting ", a technique using a band of molten material moving through the crystal, further increased crystal purity. In 1955, Carl Frosch and Lincoln Derick accidentally grew

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