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For information on semiconductor physics, see semiconductor. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that

Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium, and gallium arsenide. An electronic component is a basic electronic element usually packaged in a discrete form with two or more connecting leads or metallic pads Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Germanium (dʒɚˈmeɪniəm is a Chemical element with the symbol Ge and Atomic number 32 Gallium arsenide ( GaAs) is a compound of two elements Gallium and Arsenic. Semiconductor devices have replaced thermionic devices (vacuum tubes) in most applications. This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. They use electronic conduction in the solid state as opposed to the gaseous state or thermionic emission in a high vacuum. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Electrical conduction is the movement of electrically charged particles through a Transmission medium ( Electrical conductor) Solid-state Electronic components devices and systems are based entirely on the Semiconductor, such as Transistors Microprocessor chips and This page is about the physical properties of gas as a state of matter

Semiconductor devices are manufactured both as single discrete devices and as integrated circuits (ICs), which consist of a number—from a few to millions—of devices manufactured and interconnected on a single semiconductor substrate. Microchipsjpg|right|thumb|200px|Microchips ( EPROM memory with a transparent window showing the integrated circuit inside

Contents

Semiconductor device fundamentals

The main reason why semiconductor materials are so useful is that the behaviour of a semiconductor can be easily manipulated by the addition of impurities, known as doping. In Semiconductor production doping is the process of intentionally introducing impurities into an extremely pure (also referred to as intrinsic) semiconductor to Semiconductor conductivity can be controlled by introduction of an electric field, by exposure to light, and even pressure and heat; thus, semiconductors can make excellent sensors. Electrical conductivity or specific conductivity is a measure of a material's ability to conduct an Electric current. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 Current conduction in a semiconductor occurs via mobile or "free" electrons and holes, collectively known as charge carriers. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J An electron hole is the conceptual and mathematical Opposite of an Electron, useful in the study of Physics and Chemistry. In Physics, a charge carrier denotes a free (mobile unbound particle carrying an Electric charge. Doping a semiconductor such as silicon with a small amount of impurity atoms, such as phosphorus or boron, greatly increases the number of free electrons or holes within the semiconductor. Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Boron (ˈbɔərɒn is a Chemical element with Atomic number 5 and the chemical symbol B. When a doped semiconductor contains excess holes it is called "p-type", and when it contains excess free electrons it is known as "n-type", where p (positive for holes) or n (negative for electrons) is the sign of the charge of the majority mobile charge carriers. A P-type semiconductor (P for Positive) is obtained by carrying out a process of doping, that is adding a certain type of atoms to the semiconductor in order An N-type semiconductor (N for Negative) is obtained by carrying out a process of doping, that is by adding an impurity of valence -five elements to An electron hole is the conceptual and mathematical Opposite of an Electron, useful in the study of Physics and Chemistry. The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The semiconductor material used in devices is doped under highly controlled conditions in a fabrication facility, or fab, to precisely control the location and concentration of p- and n-type dopants. In the Microelectronics industry a semiconductor fabrication plant (commonly called a fab) is a factory where devices such as Integrated circuits are manufactured The junctions which form where n-type and p-type semiconductors join together are called p-n junctions. A p-n junction is a junction formed by combining P-type and N-type Semiconductors together in very close contact

Diode

The p-n junction diode is a device made from a p-n junction. Dioden2jpg|thumb|right|150px|Figure 2 Various semiconductor diodes At the junction of a p-type and an n-type semiconductor there forms a region called the depletion zone which blocks current conduction from the n-type region to the p-type region, but allows current to conduct from the p-type region to the n-type region. In Semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region or the space charge region Thus when the device is forward biased, with the p-side at higher electric potential, the diode conducts current easily; but the current is very small when the diode is reverse biased. At a point in space the electric potential is the Potential energy per unit of charge that is associated with a static (time-invariant Electric field

Exposing a semiconductor to light can generate electron–hole pairs, which increases the number of free carriers and its conductivity. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 In the Solid state physics of Semiconductors carrier generation and recombination are processes by which mobile Electrons and Electron holes Diodes optimized to take advantage of this phenomenon are known as photodiodes. A photodiode is a type of Photodetector capable of converting Light into either current or Voltage, depending upon the mode of operation Compound semiconductor diodes can also be used to generate light, as in light-emitting diodes and laser diodes. A Compound Semiconductor is a Semiconductor Compound composed of elements from two or more different groups of the Periodic table. A laser diode is a Laser where the active medium is a Semiconductor similar to that found in a Light-emitting diode.

Transistor

Two MOS transistors with common gate (metallic layers and dielectric removed for clarity).
Two MOS transistors with common gate (metallic layers and dielectric removed for clarity). In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals

Bipolar junction transistors are formed from two p-n junctions, in either n-p-n or p-n-p configuration. A bipolar (junction transistor ( BJT) is a type of Transistor. The middle, or base, 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 the base-emitter current.

Another type of transistor, the field effect transistor operates on the principle that semiconductor conductivity can be increased or decreased by the presence of an electric field. The field-effect transistor (FET is a type of Transistor that relies on an Electric field to control the shape and hence the conductivity of a 'channel' An electric field can increase the number of free electrons and holes in a semiconductor, thereby changing its conductivity. In Physics, the space surrounding an Electric charge or in the presence of a time-varying Magnetic field has a property called an electric field (that can The field may be applied by a reverse-biased p-n junction, forming a junction field effect transistor, or JFET; or by an electrode isolated from the bulk material by an oxide layer, forming a metal-oxide-semiconductor field effect transistor, or MOSFET. The junction gate field-effect transistor ( JFET or JUGFET) is the simplest type of Field effect transistor. The metal–oxide–semiconductor field-effect transistor ( MOSFET, MOS-FET, or MOS FET) is a device used to amplify or switch electronic signals

Cross-section through a MOS transistor (metallic layers and dielectric removed for clarity), foreground.
Cross-section through a MOS transistor (metallic layers and dielectric removed for clarity), foreground.

The MOSFET is the most used semiconductor device today. The gate electrode is charged to produce an electric field that controls the conductivity of a "channel" between two terminals, called the source and drain. In Physics, the space surrounding an Electric charge or in the presence of a time-varying Magnetic field has a property called an electric field (that can Electrical conductivity or specific conductivity is a measure of a material's ability to conduct an Electric current. 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.

Semiconductor device materials

Main article: Semiconductor materials

By far, silicon (Si) is the most widely used material in semiconductor devices. A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that Silicon (ˈsɪlɪkən or /ˈsɪlɪkɒn/ silicium is the Chemical element that has the symbol Si and Atomic number 14 Its combination of low raw material cost, relatively simple processing, and a useful temperature range make 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. A boule is a single-crystal Ingot produced by synthetic means The Millimetre ( American spelling: millimeter, symbol mm) is a unit of Length in the Metric system, equal to Inches redirects here To see the Les Savy Fav album see Inches. A wafer is a thin slice of Semiconductor material such as a Silicon crystal used in the fabrication of Integrated circuit and other microdevices

Germanium (Ge) was a widely used early semiconductor material but its thermal sensitivity makes it less useful than silicon. Germanium (dʒɚˈmeɪniəm is a Chemical element with the symbol Ge and Atomic number 32 Today, germanium is often alloyed with silicon for use in very-high-speed SiGe devices; IBM is a major producer of such devices. International Business Machines Corporation abbreviated IBM and nicknamed "Big Blue", is a multinational Computer Technology

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 the wafer diameter to sizes significantly smaller than silicon wafers thus making mass production of GaAs devices significantly more expensive than silicon. Gallium arsenide ( GaAs) is a compound of two elements Gallium and Arsenic.

Other less common materials are also in use or under investigation.

Silicon carbide (SiC) has found some application as the raw material for blue light-emitting diodes (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. Silicon carbide ( is a compound of Silicon and Carbon bonded together to form Ceramics but it also occurs in nature as the extremely rare mineral Image talkNew_radiation_symbol_ISO_21482svg for details --> Ionizing radiation IMPATT diodes have also been fabricated from SiC. An IMPATT diode ( IMP act ionization A valanche T ransit- T ime is a form of high power Diode used in high-frequency electronics and

Various indium compounds (indium arsenide, indium antimonide, and indium phosphide) are also being used in LEDs and solid state laser diodes. Indium (ˈɪndiəm is a Chemical element with chemical symbol In and Atomic number 49 Antimony (IPA (Received Pronunciation, /ˈæntɪmoʊni/ (US is a Chemical element with the symbol Sb (stibium meaning "mark" and Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 A laser diode is a Laser where the active medium is a Semiconductor similar to that found in a Light-emitting diode. Selenium sulfide is being studied in the manufacture of photovoltaic solar cells. Selenium (səˈliniəm is a Chemical element with the Atomic number 34 represented by the chemical symbol Se, an atomic mass of 78 The term sulfide ( sulphide in British English) refers to several types of Chemical compounds containing Sulfur in its lowest Oxidation Photovoltaics ( PV) is the field of technology and research related to the application of Solar cells for Energy by converting Sunlight directly A solar cell or photovoltaic cell is a device that converts Solar energy into Electricity by the photovoltaic effect.

List of common semiconductor devices

Two-terminal devices:

Three-terminal devices:

Four-terminal devices:

Multi-terminal devices:

Semiconductor device applications

All transistor types can be used as the building blocks of logic gates, which are fundamental in the design of digital circuits. An avalanche diode is a Diode (usually made from Silicon, but can be made from another Semiconductor) that is designed to go through Avalanche breakdown The DIAC, or diode for alternating current, is a bidirectional trigger Diode that conducts current only after its Breakdown voltage has been Dioden2jpg|thumb|right|150px|Figure 2 Various semiconductor diodes A Gunn diode, also known as a transferred electron device ( TED) is a form of Diode used in high-frequency Electronics. An IMPATT diode ( IMP act ionization A valanche T ransit- T ime is a form of high power Diode used in high-frequency electronics and A laser diode is a Laser where the active medium is a Semiconductor similar to that found in a Light-emitting diode. Photosensors or photodetectors are Sensors of Light or other Electromagnetic energy A PiN diode is a Diode with a wide lightly doped 'near' Intrinsic semiconductor region between a P-type semiconductor and an N-type semiconductor The Schottky diode (named after German physicist Walter H Schottky; also known as hot carrier diode) is a Semiconductor Diode with A solar cell or photovoltaic cell is a device that converts Solar energy into Electricity by the photovoltaic effect. A tunnel Diode or Esaki diode is a type of Semiconductor diode which is capable of very fast operation well into the Microwave frequency The vertical-cavity surface-emitting laser ( VCSEL;) is a type of semiconductor Laser diode with Laser beam emission perpendicular from the top surface A vertical-external-cavity surface-emitting-laser ( VECSEL) is a small Semiconductor laser similar to a Vertical-cavity surface-emitting laser (VCSEL A Zener diode is a type of Diode that permits current in the forward direction like a normal diode but also in the reverse direction if the voltage is larger A bipolar (junction transistor ( BJT) is a type of Transistor. In Electronics, the Darlington transistor (often called a Darlington pair) is a Semiconductor device which combines two Bipolar transistors in The field-effect transistor (FET is a type of Transistor that relies on an Electric field to control the shape and hence the conductivity of a 'channel' The insulated-gate bipolar transistor or IGBT is a three-terminal Power semiconductor device, noted for high efficiency and fast switching A silicon-controlled rectifier (or semiconductor-controlled rectifier) is a four-layer solid state device that controls current. The thyristor is a solid-state Semiconductor device with four layers of alternating N and P-type material A TRIAC, or TRIode for Alternating Current is an electronic component approximately equivalent to two Silicon-controlled rectifiers ( SCRs A unijunction transistor ( UJT) is an electronic Semiconductor device that has only one junction A Hall effect sensor is a Transducer that varies its output Voltage in response to changes in Magnetic field. A charge-coupled device ( CCD) is an analog Shift register, that enables the transportation of analog signals (electric charges through successive stages (capacitors A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated A logic gate performs a logical operation on one or more logic inputs and produces a single logic output Digital electronics are Electronics systems that use Digital signals Digital electronics are representations of Boolean algebra also see In digital circuits like microprocessors, transistors act as on-off switches; in the MOSFET, for instance, the voltage applied to the gate determines whether the switch is on or off. A microprocessor incorporates most or all of the functions of a Central processing unit (CPU on a single Integrated Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical A switch is a mechanical device used to connect and disconnect an electric Circuit at will

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. Analogue electronics (or analog in American English) are those electronic systems with a continuously Variable signal Common analog circuits include amplifiers and oscillators. Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal. Oscillation is the repetitive variation typically in Time, of some measure about a central value (often a point of Equilibrium) or between two or more different states

Circuits that interface or translate between digital circuits and analog circuits are known as mixed-signal circuits. A mixed-signal Integrated circuit combines Analog circuits, used for analog signal processing with Digital signal processing (DSP circuits on a single

Power semiconductor devices are discrete devices or integrated circuits intended for high current or high voltage applications. Power semiconductor devices are semiconductor devices used as switches or rectifiers in power electronic circuits ( switch mode power supplies 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.

Component identifiers

The type designators of semiconductor devices are often manufacturer specific. Nevertheless, there have been attempts at creating standards for type codes, and a subset of devices follow those. For discrete devices, for example, there are three standards: JEDEC JESD370B in USA, Pro Electron in Europe and JIS in Japan. A discrete device (or discrete component) is an Electronic component with just one Circuit element, either passive ( Resistor, JEDEC Solid State Technology Association, formerly known as J oint E lectron D evice E ngineering C ouncil ( JEDEC) or Joint The United States of America —commonly referred to as the Pro Electron is the European type designation and registration system for Active components (such as Semiconductors Liquid crystal displays sensor devices This article is about Japanese Industrial Standards in general see JIS encoding for the character encoding used in representing the Japanese language for computer software For a topic outline on this subject see List of basic Japan topics.

History of semiconductor device development

1900s

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". Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light. Cat’s whisker refers to a thin Wire that lightly touches a semiconducting crystal to make an imperfect contact-junction detector in a Crystal radio These detectors were somewhat troublesome, however, requiring 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. Galena is the natural mineral form of Lead sulfide. It is the most important Lead Ore mineral Silicon carbide ( is a compound of Silicon and Carbon bonded together to form Ceramics but it also occurs in nature as the extremely rare mineral 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 the more reliable and amplified vacuum tube based radios, the cat's whisker systems quickly disappeared. This article is about the electronic device not an evacuated pipe used for experiments in Free-fall. The "cat's whisker" is a primitive example of a special type of diode still popular today, called a Schottky diode. The Schottky diode (named after German physicist Walter H Schottky; also known as hot carrier diode) is a Semiconductor Diode with

World War II

During World War II, radar research quickly pushed radar receivers to operate at ever higher frequencies and the traditional tube based radio receivers no longer worked well. Radar is a system that uses electromagnetic waves to identify the range altitude direction or speed of both moving and fixed objects such as Aircraft, ships Frequency is a measure of the number of occurrences of a repeating event per unit Time. 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. A cavity magnetron is a high-powered Vacuum tube that generates coherent Microwaves They are commonly found in Microwave ovens as well as various The Tizard Mission officially the British Technical and Scientific Mission was a British delegation that visited the United

On a whim, Russell Ohl of Bell Laboratories decided to try a cat's whisker. Russell Ohl (1898 - 1987 was an American engineer who is generally recognized for Patenting the modern Solar cell (US Patent 2402662 "Light sensitive device" Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) is the Research organization By this point they had not been in use for a number of years, and no one at 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. Manhattan Island, in New York Harbor, is much the largest part of the Borough of Manhattan, one of the Five Boroughs which form the City of New York

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 behaviour 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 interestingly, it had 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 behaviour 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 the crack. Walter Houser Brattain ( February 10, 1902 – October 13, 1987) was an American physicist at Bell Labs who along with

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 electrical 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 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 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 is off has to do with the separation of charge carriers around the junction. In Physics, a charge carrier denotes a free (mobile unbound particle carrying an Electric charge. This is called a "depletion region". In Semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region or the space charge region

Development of the diode

Armed with the knowledge of how these new diodes worked, a vigorous effort began in order 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. Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) is the Research organization The University of Chicago is a Private university located principally in the Hyde Park neighborhood of Chicago. Within a year germanium production had been perfected to the point where military-grade diodes were being used in most radar sets.

Development of the transistor

After the war, William Shockley decided to attempt the building of a triode-like semiconductor device. William Bradford Shockley ( February 13, 1910 &ndash August 12, 1989) was a British -born American Physicist A triode is an electronic amplification device having three active electrodes He secured funding and lab space, and went to work on the problem with Brattain and John Bardeen. John Bardeen ( May 23 1908 – January 30 1991) was an American Physicist and Electrical engineer, who won

The key to the development of the transistor was the further understanding of the process of the electron mobility in a semiconductor. In Physics, electron mobility (or simply mobility) is a quantity relating the Drift velocity of Electrons to the applied Electric field It was realized that if there was some way to control the flow of the electrons from the emitter to the collector of this newly discovered diode, one could build an amplifier. For instance, if you placed contacts on either side of a single type of crystal the current would not flow through it. 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 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. Generally an amplifier or simply amp, is any device that changes usually increases the amplitude of a signal. 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 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 a new branch of quantum mechanics known as surface physics to account for the behaviour. Quantum mechanics is the study of mechanical systems whose dimensions are close to the Atomic scale such as Molecules Atoms Electrons Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including Solid - Liquid 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 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, a single larger surface would serve. The emitter and collector leads would both be placed very close together on the top, with the control lead placed on the base of the crystal. When current was applied to the "base" lead, the electrons or holes would be pushed out, across the block of 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 first transistor

A stylized replica of the first transistor
A stylized replica of the first transistor

The Bell team made many attempts to build such 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 the plastic was pushed down onto the surface of a crystal and voltage 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 the first demonstration to higher-ups at Bell Labs on the afternoon of 23 December 1947, often given as the birthdate of the transistor. Events 962 - Byzantine-Arab Wars: Under the future Emperor Nicephorus Phocas, Byzantine troops stormed the city Year 1947 ( MCMXLVII) was a Common year starting on Wednesday (link will display full 1947 calendar of the Gregorian calendar. The "PNP point-contact germanium transistor" operated as a speech amplifier with a power gain of 18 in that trial. Known generally as a point-contact transistor today, John Bardeen, Walter Houser Brattain, and William Bradford Shockley were awarded the Nobel Prize in physics for their work in 1956. A point-contact transistor was the first type of solid-state electronic Transistor ever constructed John Bardeen ( May 23 1908 – January 30 1991) was an American Physicist and Electrical engineer, who won Walter Houser Brattain ( February 10, 1902 – October 13, 1987) was an American physicist at Bell Labs who along with William Bradford Shockley ( February 13, 1910 &ndash August 12, 1989) was a British -born American Physicist The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature

Origin of the term "transistor"

Bell Telephone Laboratories needed 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. John Robinson Pierce ( March 27, 1910 &ndash April 2, 2002) was an American Engineer and Author. 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. Events 585 BC - A Solar eclipse occurs as predicted by Greek philosopher and scientist Thales, while Alyattes is battling Year 1948 ( MCMXLVIII) was a Leap year starting on Thursday (link will display the 1948 calendar of the Gregorian calendar. This 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.

Improvements in transistor design

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 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. Julius Edgar Lilienfeld ( April 18, 1881 &ndash August 28, 1963) was an Austrian-Hungarian physicist

Shockley was incensed, and decided to demonstrate who was the real brains of the operation. Only a few months later he invented an entirely new type of transistor with a layer or 'sandwich' structure. This new form was considerably more robust than the fragile point-contact system, and would go on to be used for the vast majority of all transistors into the 1960s. It would evolve into the bipolar junction transistor. A bipolar (junction transistor ( BJT) is a type of Transistor.

With the fragility problems solved, a remaining problem was purity. Making germanium of the required purity was proving to be a serious problem, and limited the number of transistors that actually worked from a given batch of material. Germanium (dʒɚˈmeɪniəm is a Chemical element with the symbol Ge and Atomic number 32 Germanium's sensitivity to temperature also limited its usefulness. Scientists theorized that silicon would be easier to fabricate, but few bothered to investigate this possibility. Gordon K. Teal was the first to develop a working silicon transistor, and his company, the nascent Texas Instruments, profited from its technological edge. Gordon Kidd Teal ( January 10, 1907 &ndash January 7, 2003) invented a method of applying the Czochralski method to produce extremely Texas Instruments ( better known in the electronics industry (and popularly as TI, is an American company based in Dallas, Texas, USA Germanium disappeared from most transistors by the late 1960s.

Within a few years, transistor-based products, most notably radios, were appearing on the market. A major improvement in manufacturing yield came when a chemist advised the companies fabricating semiconductors to use distilled water rather than tap water: calcium ions were the cause of the poor yields. Purified water is water from any source that is physically processed to remove impurities Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge "Zone melting", a technique using a moving band of molten material through the crystal, further increased the purity of the available crystals. Zone melting is a method of separation by melting in which a molten zone traverses a long Ingot of impure metal or chemical

See also

References

Links

Semiconductor Timeline Exhibit - Computer History Museum

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