Mike Fright is a 1934 Our Gang short comedy film directed by Gus Meins . It was the 130th Our Gang short to be released.
119-569: When open auditions are announced for a radio variety program, the local station is besieged by aggressively over-coached "professional kids." Also auditioning is the International Silver String Submarine Band —which turns out to be the gang, equipped (or rather, armed) with home-made instruments. They suffer through an endless parade of cute kiddie troupers, and accidentally knock over the microphone several times, which inadvertently blows tubes and bulbs in
238-515: 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
357-488: A vacuum (typically liberated by thermionic emission ) or as free electrons and ions through an ionized gas . Semiconductor devices are manufactured both as single discrete devices and as integrated circuits , which consist of two or more devices—which can number from 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
476-404: A beam of electrons for display purposes (such as the television picture tube, in electron microscopy , and in electron beam lithography ); X-ray tubes ; phototubes and photomultipliers (which rely on electron flow through a vacuum where electron emission from the cathode depends on energy from photons rather than thermionic emission ). A vacuum tube consists of two or more electrodes in
595-550: A blower, or water-jacket. Klystrons and magnetrons often operate their anodes (called collectors in klystrons) at ground potential to facilitate cooling, particularly with water, without high-voltage insulation. These tubes instead operate with high negative voltages on the filament and cathode. Except for diodes, additional electrodes are positioned between the cathode and the plate (anode). These electrodes are referred to as grids as they are not solid electrodes but sparse elements through which electrons can pass on their way to
714-649: A blue glow. Finnish inventor Eric Tigerstedt significantly improved on the original triode design in 1914, while working on his sound-on-film process in Berlin, Germany. Tigerstedt's innovation was to make the electrodes concentric cylinders with the cathode at the centre, thus greatly increasing the collection of emitted electrons at the anode. Irving Langmuir at the General Electric research laboratory ( Schenectady, New York ) had improved Wolfgang Gaede 's high-vacuum diffusion pump and used it to settle
833-401: A certain sound or tone). Not all electronic circuit valves or electron tubes are vacuum tubes. Gas-filled tubes are similar devices, but containing a gas, typically at low pressure, which exploit phenomena related to electric discharge in gases , usually without a heater. One classification of thermionic vacuum tubes is by the number of active electrodes . A device with two active elements
952-422: 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
1071-501: A combination of a triode with a hexode and even an octode have been used for this purpose. The additional grids include control grids (at a low potential) and screen grids (at a high voltage). Many designs use such a screen grid as an additional anode to provide feedback for the oscillator function, whose current adds to that of the incoming radio frequency signal. The pentagrid converter thus became widely used in AM receivers, including
1190-466: A common circuit (which can be AC without inducing hum) while allowing the cathodes in different tubes to operate at different voltages. H. J. Round invented the indirectly heated tube around 1913. The filaments require constant and often considerable power, even when amplifying signals at the microwatt level. Power is also dissipated when the electrons from the cathode slam into the anode (plate) and heat it; this can occur even in an idle amplifier due to
1309-586: A far superior and versatile technology for use in radio transmitters and receivers. At the end of the 19th century, radio or wireless technology was in an early stage of development and the Marconi Company was engaged in development and construction of radio communication systems. Guglielmo Marconi appointed English physicist John Ambrose Fleming as scientific advisor in 1899. Fleming had been engaged as scientific advisor to Edison Telephone (1879), as scientific advisor at Edison Electric Light (1882), and
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#17328013283131428-411: 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
1547-418: A high vacuum between electrodes to which an electric potential difference has been applied. The type known as a thermionic tube or thermionic valve utilizes thermionic emission of electrons from a hot cathode for fundamental electronic functions such as signal amplification and current rectification . Non-thermionic types such as a vacuum phototube , however, achieve electron emission through
1666-415: A higher electric potential than the n-side), this depletion region is diminished, allowing for significant conduction. Contrariwise, only 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
1785-435: 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
1904-400: A low potential space charge region between the anode and screen grid to return anode secondary emission electrons to the anode when the anode potential is less than that of the screen grid. Formation of beams also reduces screen grid current. In some cylindrically symmetrical beam power tubes, the cathode is formed of narrow strips of emitting material that are aligned with the apertures of
2023-420: 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
2142-414: A pair of beam deflection electrodes which deflected the current towards either of two anodes. They were sometimes known as the 'sheet beam' tubes and used in some color TV sets for color demodulation . The similar 7360 was popular as a balanced SSB (de)modulator . A beam tetrode (or "beam power tube") forms the electron stream from the cathode into multiple partially collimated beams to produce
2261-412: A printing instrument was needed. As a result of experiments conducted on Edison effect bulbs, Fleming developed a vacuum tube that he termed the oscillation valve because it passed current in only one direction. The cathode was a carbon lamp filament, heated by passing current through it, that produced thermionic emission of electrons. Electrons that had been emitted from the cathode were attracted to
2380-509: A relatively low-value resistor is connected between the cathode and ground. This makes the cathode positive with respect to the grid, which is at ground potential for DC. However C batteries continued to be included in some equipment even when the "A" and "B" batteries had been replaced by power from the AC mains. That was possible because there was essentially no current draw on these batteries; they could thus last for many years (often longer than all
2499-533: 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 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
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#17328013283132618-407: A simple oscillator only requiring connection of the plate to a resonant LC circuit to oscillate. The dynatron oscillator operated on the same principle of negative resistance as the tunnel diode oscillator many years later. The dynatron region of the screen grid tube was eliminated by adding a grid between the screen grid and the plate to create the pentode . The suppressor grid of the pentode
2737-549: 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
2856-419: A small-signal vacuum tube are 1 to 10 millisiemens. It is one of the three 'constants' of a vacuum tube, the other two being its gain μ and plate resistance R p or R a . The Van der Bijl equation defines their relationship as follows: g m = μ R p {\displaystyle g_{m}={\mu \over R_{p}}} The non-linear operating characteristic of
2975-563: 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
3094-449: 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
3213-464: A vacuum inside an airtight envelope. Most tubes have glass envelopes with a glass-to-metal seal based on kovar sealable borosilicate glasses , although ceramic and metal envelopes (atop insulating bases) have been used. The electrodes are attached to leads which pass through the envelope via an airtight seal. Most vacuum tubes have a limited lifetime, due to the filament or heater burning out or other failure modes, so they are made as replaceable units;
3332-429: A wide range of frequencies. To combat the stability problems of the triode as a radio frequency amplifier due to grid-to-plate capacitance, the physicist Walter H. Schottky invented the tetrode or screen grid tube in 1919. He showed that the addition of an electrostatic shield between the control grid and the plate could solve the problem. This design was refined by Hull and Williams. The added grid became known as
3451-445: Is a current . Compare this to the behavior of the bipolar junction transistor , in which the controlling signal is a current and the output is also a current. For vacuum tubes, transconductance or mutual conductance ( g m ) is defined as the change in the plate(anode)/cathode current divided by the corresponding change in the grid to cathode voltage, with a constant plate(anode) to cathode voltage. Typical values of g m for
3570-489: Is a diode , usually used for rectification . Devices with three elements are triodes used for amplification and switching . Additional electrodes create tetrodes , pentodes , and so forth, which have multiple additional functions made possible by the additional controllable electrodes. Other classifications are: Vacuum tubes may have other components and functions than those described above, and are described elsewhere. These include as cathode-ray tubes , which create
3689-429: 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
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3808-578: 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
3927-438: Is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon , germanium , and gallium arsenide , as well as organic semiconductors ) for its function. Its conductivity lies between conductors and insulators. Semiconductor devices have replaced vacuum tubes in most applications. They conduct electric current in the solid state , rather than as free electrons across
4046-491: 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
4165-453: 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,
4284-555: 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)
4403-478: Is cut short because the gang is distractingly eating lemons! Mike Fright was the first Our Gang short since Pups Is Pups to not contain the opening "Good Old Days" Our Gang theme song. Instead, it was replaced with the Leroy Shield incidental tune "Little Dancing Girl", which appeared as background music in many of the films and would be the music used for the first 4 minutes of this episode. Because
4522-410: Is not important since they are simply re-captured by the plate. But in a tetrode they can be captured by the screen grid since it is also at a positive voltage, robbing them from the plate current and reducing the amplification of the tube. Since secondary electrons can outnumber the primary electrons over a certain range of plate voltages, the plate current can decrease with increasing plate voltage. This
4641-446: 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
4760-564: Is the Loewe 3NF . This 1920s device has three triodes in a single glass envelope together with all the fixed capacitors and resistors required to make a complete radio receiver. As the Loewe set had only one tube socket, it was able to substantially undercut the competition, since, in Germany, state tax was levied by the number of sockets. However, reliability was compromised, and production costs for
4879-416: Is the dynatron region or tetrode kink and is an example of negative resistance which can itself cause instability. Another undesirable consequence of secondary emission is that screen current is increased, which may cause the screen to exceed its power rating. The otherwise undesirable negative resistance region of the plate characteristic was exploited with the dynatron oscillator circuit to produce
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4998-439: 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)
5117-564: The Edison effect , that became well known. Although Edison was aware of the unidirectional property of current flow between the filament and the anode, his interest (and patent ) concentrated on the sensitivity of the anode current to the current through the filament (and thus filament temperature). It was years later that John Ambrose Fleming applied the rectifying property of the Edison effect to detection of radio signals, as an improvement over
5236-684: The plate ( anode ) when the plate was at a positive voltage with respect to the cathode. Electrons could not pass in the reverse direction because the plate was not heated and not capable of thermionic emission of electrons. Fleming filed a patent for these tubes, assigned to the Marconi company, in the UK in November 1904 and this patent was issued in September 1905. Later known as the Fleming valve ,
5355-429: The screen grid or shield grid . The screen grid is operated at a positive voltage significantly less than the plate voltage and it is bypassed to ground with a capacitor of low impedance at the frequencies to be amplified. This arrangement substantially decouples the plate and the control grid , eliminating the need for neutralizing circuitry at medium wave broadcast frequencies. The screen grid also largely reduces
5474-480: The 6GH8 /ECF82 triode-pentode, quite popular in television receivers. The desire to include even more functions in one envelope resulted in the General Electric Compactron which has 12 pins. A typical example, the 6AG11, contains two triodes and two diodes. Some otherwise conventional tubes do not fall into standard categories; the 6AR8, 6JH8 and 6ME8 have several common grids, followed by
5593-482: The 6SN7 , is a "dual triode" which performs the functions of two triode tubes while taking up half as much space and costing less. The 12AX7 is a dual "high mu" (high voltage gain ) triode in a miniature enclosure, and became widely used in audio signal amplifiers, instruments, and guitar amplifiers . The introduction of the miniature tube base (see below) which can have 9 pins, more than previously available, allowed other multi-section tubes to be introduced, such as
5712-467: The magnetic detector . Amplification by vacuum tube became practical only with Lee de Forest 's 1907 invention of the three-terminal " audion " tube, a crude form of what was to become the triode . Being essentially the first electronic amplifier , such tubes were instrumental in long-distance telephony (such as the first coast-to-coast telephone line in the US) and public address systems , and introduced
5831-438: The photoelectric effect , and are used for such purposes as the detection of light intensities. In both types, the electrons are accelerated from the cathode to the anode by the electric field in the tube. The simplest vacuum tube, the diode (i.e. Fleming valve ), was invented in 1904 by John Ambrose Fleming . It contains only a heated electron-emitting cathode and an anode. Electrons can flow in only one direction through
5950-468: The quiescent current necessary to ensure linearity and low distortion. In a power amplifier, this heating can be considerable and can destroy the tube if driven beyond its safe limits. Since the tube contains a vacuum, the anodes in most small and medium power tubes are cooled by radiation through the glass envelope. In some special high power applications, the anode forms part of the vacuum envelope to conduct heat to an external heat sink, usually cooled by
6069-462: The spark gap transmitter for radio or mechanical computers for computing, it was the invention of the thermionic vacuum tube that made these technologies widespread and practical, and created the discipline of electronics . In the 1940s, the invention of semiconductor devices made it possible to produce solid-state devices, which are smaller, safer, cooler, and more efficient, reliable, durable, and economical than thermionic tubes. Beginning in
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#17328013283136188-928: 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
6307-413: The 19th century, telegraph and telephone engineers had recognized the need to extend the distance that signals could be transmitted. In 1906, Robert von Lieben filed for a patent for a cathode-ray tube which used an external magnetic deflection coil and was intended for use as an amplifier in telephony equipment. This von Lieben magnetic deflection tube was not a successful amplifier, however, because of
6426-485: The Audion for demonstration to AT&T's engineering department. Dr. Harold D. Arnold of AT&T recognized that the blue glow was caused by ionized gas. Arnold recommended that AT&T purchase the patent, and AT&T followed his recommendation. Arnold developed high-vacuum tubes which were tested in the summer of 1913 on AT&T's long-distance network. The high-vacuum tubes could operate at high plate voltages without
6545-544: 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
6664-453: 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
6783-400: The allied military by 1916. Historically, vacuum levels in production vacuum tubes typically ranged from 10 μPa down to 10 nPa (8 × 10 Torr down to 8 × 10 Torr). The triode and its derivatives (tetrodes and pentodes) are transconductance devices, in which the controlling signal applied to the grid is a voltage , and the resulting amplified signal appearing at the anode
6902-412: 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
7021-409: The base. There was even an occasional design that had two top cap connections. The earliest vacuum tubes evolved from incandescent light bulbs , containing a filament sealed in an evacuated glass envelope. When hot, the filament in a vacuum tube (a cathode ) releases electrons into the vacuum, a process called thermionic emission . This can produce a controllable unidirectional current though
7140-536: The cathode, no direct current could pass from the cathode to the grid. Thus a change of voltage applied to the grid, requiring very little power input to the grid, could make a change in the plate current and could lead to a much larger voltage change at the plate; the result was voltage and power amplification . In 1908, de Forest was granted a patent ( U.S. patent 879,532 ) for such a three-electrode version of his original Audion for use as an electronic amplifier in radio communications. This eventually became known as
7259-429: The control grid, reducing control grid current. This design helps to overcome some of the practical barriers to designing high-power, high-efficiency power tubes. Manufacturer's data sheets often use the terms beam pentode or beam power pentode instead of beam power tube , and use a pentode graphic symbol instead of a graphic symbol showing beam forming plates. Semiconductor device A semiconductor device
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#17328013283137378-557: The control room, causing the hat worn by the sound man , played by vaudevillian Sid Walker, to be literally blown off his head, and making his hair stand on end. The gang then steal the show with a rendition of " The Daring Young Man on the Flying Trapeze ." Musical numbers include Jimmy had a Nickel (by Maurice Sigler ), My Little Grass Shack in Kealakekua, Hawaii , and My Wild Irish Rose (by Chauncey Olcott ), which
7497-446: 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
7616-424: 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
7735-466: 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 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
7854-565: The device – from the cathode to the anode. Adding one or more control grids within the tube allows the current between the cathode and anode to be controlled by the voltage on the grids. These devices became a key component of electronic circuits for the first half of the twentieth century. They were crucial to the development of radio , television , radar , sound recording and reproduction , long-distance telephone networks, and analog and early digital computers . Although some applications had used earlier technologies such as
7973-418: The electrode leads connect to pins on the tube's base which plug into a tube socket . Tubes were a frequent cause of failure in electronic equipment, and consumers were expected to be able to replace tubes themselves. In addition to the base terminals, some tubes had an electrode terminating at a top cap . The principal reason for doing this was to avoid leakage resistance through the tube base, particularly for
8092-399: 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
8211-410: 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
8330-425: The exception of early light bulbs , such tubes were only used in scientific research or as novelties. The groundwork laid by these scientists and inventors, however, was critical to the development of subsequent vacuum tube technology. Although thermionic emission was originally reported in 1873 by Frederick Guthrie , it was Thomas Edison's apparently independent discovery of the phenomenon in 1883, referred to as
8449-403: The filament as the cathode; this is called a "directly heated" tube. Most modern tubes are "indirectly heated" by a "heater" element inside a metal tube that is the cathode. The heater is electrically isolated from the surrounding cathode and simply serves to heat the cathode sufficiently for thermionic emission of electrons. The electrical isolation allows all the tubes' heaters to be supplied from
8568-450: 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
8687-417: The first time to exceed 1 trillion, meaning that well over 7 trillion have been made to date. A semiconductor diode 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
8806-400: The high impedance grid input. The bases were commonly made with phenolic insulation which performs poorly as an insulator in humid conditions. Other reasons for using a top cap include improving stability by reducing grid-to-anode capacitance, improved high-frequency performance, keeping a very high plate voltage away from lower voltages, and accommodating one more electrode than allowed by
8925-411: The influence of the plate voltage on the space charge near the cathode, permitting the tetrode to produce greater voltage gain than the triode in amplifier circuits. While the amplification factors of typical triodes commonly range from below ten to around 100, tetrode amplification factors of 500 are common. Consequently, higher voltage gains from a single tube amplification stage became possible, reducing
9044-439: 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
9163-496: 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
9282-420: 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
9401-549: 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
9520-530: 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 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
9639-573: The mid-1960s, thermionic tubes were being replaced by the transistor . However, the cathode-ray tube (CRT) remained the basis for television monitors and oscilloscopes until the early 21st century. Thermionic tubes are still employed in some applications, such as the magnetron used in microwave ovens, certain high-frequency amplifiers , and high end audio amplifiers, which many audio enthusiasts prefer for their "warmer" tube sound , and amplifiers for electric musical instruments such as guitars (for desired effects, such as "overdriving" them to achieve
9758-445: The miniature tube version of the " All American Five ". Octodes, such as the 7A8, were rarely used in the United States, but much more common in Europe, particularly in battery operated radios where the lower power consumption was an advantage. To further reduce the cost and complexity of radio equipment, two separate structures (triode and pentode for instance) can be combined in the bulb of a single multisection tube . An early example
9877-564: 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
9996-416: The nature of this film was a talent show with a variety of musical selections, additional background music was not used, nor was it needed. This article related to a short comedy film is a stub . You can help Misplaced Pages by expanding it . Vacuum tube A vacuum tube , electron tube , valve (British usage), or tube (North America) is a device that controls electric current flow in
10115-431: The number of external pins (leads) often forced the functions to share some of those external connections such as their cathode connections (in addition to the heater connection). The RCA Type 55 is a double diode triode used as a detector, automatic gain control rectifier and audio preamplifier in early AC powered radios. These sets often include the 53 Dual Triode Audio Output. Another early type of multi-section tube,
10234-402: 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 , the region between
10353-435: The number of tubes required. Screen grid tubes were marketed by late 1927. However, the useful region of operation of the screen grid tube as an amplifier was limited to plate voltages greater than the screen grid voltage, due to secondary emission from the plate. In any tube, electrons strike the plate with sufficient energy to cause the emission of electrons from its surface. In a triode this secondary emission of electrons
10472-399: 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
10591-528: The oscillation valve was developed for the purpose of rectifying radio frequency current as the detector component of radio receiver circuits. While offering no advantage over the electrical sensitivity of crystal detectors , the Fleming valve offered advantage, particularly in shipboard use, over the difficulty of adjustment of the crystal detector and the susceptibility of the crystal detector to being dislodged from adjustment by vibration or bumping. In
10710-652: The plate current, possibly changing the output by hundreds of volts (depending on the circuit). The solid-state device which operates most like the pentode tube is the junction field-effect transistor (JFET), although vacuum tubes typically operate at over a hundred volts, unlike most semiconductors in most applications. The 19th century saw increasing research with evacuated tubes, such as the Geissler and Crookes tubes . The many scientists and inventors who experimented with such tubes include Thomas Edison , Eugen Goldstein , Nikola Tesla , and Johann Wilhelm Hittorf . With
10829-471: The plate, it creates an electric field due to the potential difference between them. Such a tube with only two electrodes is termed a diode , and is used for rectification . Since current can only pass in one direction, such a diode (or rectifier ) will convert alternating current (AC) to pulsating DC. Diodes can therefore be used in a DC power supply , as a demodulator of amplitude modulated (AM) radio signals and for similar functions. Early tubes used
10948-405: The plate. The vacuum tube is then known as a triode , tetrode , pentode , etc., depending on the number of grids. A triode has three electrodes: the anode, cathode, and one grid, and so on. The first grid, known as the control grid, (and sometimes other grids) transforms the diode into a voltage-controlled device : the voltage applied to the control grid affects the current between the cathode and
11067-414: The plate. When held negative with respect to the cathode, the control grid creates an electric field that repels electrons emitted by the cathode, thus reducing or even stopping the current between cathode and anode. As long as the control grid is negative relative to the cathode, essentially no current flows into it, yet a change of several volts on the control grid is sufficient to make a large difference in
11186-399: The power used by the deflection coil. Von Lieben would later make refinements to triode vacuum tubes. Lee de Forest is credited with inventing the triode tube in 1907 while experimenting to improve his original (diode) Audion . By placing an additional electrode between the filament ( cathode ) and plate (anode), he discovered the ability of the resulting device to amplify signals. As
11305-448: The present-day C cell , for which the letter denotes its size and shape). The C battery's positive terminal was connected to the cathode of the tubes (or "ground" in most circuits) and whose negative terminal supplied this bias voltage to the grids of the tubes. Later circuits, after tubes were made with heaters isolated from their cathodes, used cathode biasing , avoiding the need for a separate negative power supply. For cathode biasing,
11424-532: The question of thermionic emission and conduction in a vacuum. Consequently, General Electric started producing hard vacuum triodes (which were branded Pliotrons) in 1915. Langmuir patented the hard vacuum triode, but de Forest and AT&T successfully asserted priority and invalidated the patent. Pliotrons were closely followed by the French type ' TM ' and later the English type 'R' which were in widespread use by
11543-440: The suppressor grid wired internally to the cathode (e.g. EL84/6BQ5) and those with the suppressor grid wired to a separate pin for user access (e.g. 803, 837). An alternative solution for power applications is the beam tetrode or beam power tube , discussed below. Superheterodyne receivers require a local oscillator and mixer , combined in the function of a single pentagrid converter tube. Various alternatives such as using
11662-426: 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,
11781-474: 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
11900-438: 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
12019-559: 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
12138-458: The triode caused early tube audio amplifiers to exhibit harmonic distortion at low volumes. Plotting plate current as a function of applied grid voltage, it was seen that there was a range of grid voltages for which the transfer characteristics were approximately linear. To use this range, a negative bias voltage had to be applied to the grid to position the DC operating point in the linear region. This
12257-407: The triode. De Forest's original device was made with conventional vacuum technology. The vacuum was not a "hard vacuum" but rather left a very small amount of residual gas. The physics behind the device's operation was also not settled. The residual gas would cause a blue glow (visible ionization) when the plate voltage was high (above about 60 volts). In 1912, de Forest and John Stone Stone brought
12376-646: The tube were much greater. In a sense, these were akin to integrated circuits. In the United States, Cleartron briefly produced the "Multivalve" triple triode for use in the Emerson Baby Grand receiver. This Emerson set also has a single tube socket, but because it uses a four-pin base, the additional element connections are made on a "mezzanine" platform at the top of the tube base. By 1940 multisection tubes had become commonplace. There were constraints, however, due to patents and other licensing considerations (see British Valve Association ). Constraints due to
12495-482: The tubes) without requiring replacement. When triodes were first used in radio transmitters and receivers, it was found that tuned amplification stages had a tendency to oscillate unless their gain was very limited. This was due to the parasitic capacitance between the plate (the amplifier's output) and the control grid (the amplifier's input), known as the Miller capacitance . Eventually the technique of neutralization
12614-407: 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
12733-420: The vacuum known as the Edison effect . A second electrode, the anode or plate , will attract those electrons if it is at a more positive voltage. The result is a net flow of electrons from the filament to plate. However, electrons cannot flow in the reverse direction because the plate is not heated and does not emit electrons. The filament has a dual function: it emits electrons when heated; and, together with
12852-506: 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
12971-421: The voltage applied to the control grid (or simply "grid") was lowered from the cathode's voltage to somewhat more negative voltages, the amount of current from the filament to the plate would be reduced. The negative electrostatic field created by the grid in the vicinity of the cathode would inhibit the passage of emitted electrons and reduce the current to the plate. With the voltage of the grid less than that of
13090-588: 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)
13209-442: 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
13328-406: 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
13447-408: 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
13566-401: 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
13685-449: Was also technical consultant to Edison-Swan . One of Marconi's needs was for improvement of the detector , a device that extracts information from a modulated radio frequency. Marconi had developed a magnetic detector , which was less responsive to natural sources of radio frequency interference than the coherer , but the magnetic detector only provided an audio frequency signal to a telephone receiver. A reliable detector that could drive
13804-405: Was called the idle condition, and the plate current at this point the "idle current". The controlling voltage was superimposed onto the bias voltage, resulting in a linear variation of plate current in response to positive and negative variation of the input voltage around that point. This concept is called grid bias . Many early radio sets had a third battery called the "C battery" (unrelated to
13923-617: Was developed whereby the RF transformer connected to the plate (anode) would include an additional winding in the opposite phase. This winding would be connected back to the grid through a small capacitor, and when properly adjusted would cancel the Miller capacitance. This technique was employed and led to the success of the Neutrodyne radio during the 1920s. However, neutralization required careful adjustment and proved unsatisfactory when used over
14042-478: 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
14161-401: Was usually connected to the cathode and its negative voltage relative to the anode repelled secondary electrons so that they would be collected by the anode instead of the screen grid. The term pentode means the tube has five electrodes. The pentode was invented in 1926 by Bernard D. H. Tellegen and became generally favored over the simple tetrode. Pentodes are made in two classes: those with
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