- For information on how semiconductors are used as electronic devices, see Semiconductor device
A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. Commonly used semiconducting materials are silicon[1], germanium [2], gallium arsenide [3] and indium phosphide.
Some of the properties of semiconductor materials were observed throughout the mid 19th and first decades of the 20th century. The first practical application of semiconductors in electronics was the 1904 development of the cat's-whisker detector, a primitive semiconductor diode used in early radio receivers. Developments in quantum physics in turn led to the development of the transistor in 1947,[1] the integrated circuit in 1958, and the MOS transistor in 1959.
Early history of semiconductors[]
- See also: Semiconductor device and Timeline of electrical and electronic engineering
The history of the understanding of semiconductors begins with experiments on the electrical properties of materials. The properties of negative temperature coefficient of resistance, rectification, and light-sensitivity were observed starting in the early 19th century.
Thomas Johann Seebeck was the first to notice an effect due to semiconductors, in 1821.[2] In 1833, Michael Faraday reported that the resistance of specimens of silver sulfide decreases when they are heated. This is contrary to the behavior of metallic substances such as copper. In 1839, Alexandre Edmond Becquerel reported observation of a voltage between a solid and a liquid electrolyte when struck by light, the photovoltaic effect. In 1873 Willoughby Smith observed that selenium resistors exhibit decreasing resistance when light falls on them. In 1874, Karl Ferdinand Braun observed conduction and rectification in metallic sulfides, although this effect had been discovered much earlier by Peter Munck af Rosenschold (sv) writing for the Annalen der Physik und Chemie in 1835,[3] and Arthur Schuster found that a copper oxide layer on wires has rectification properties that ceases when the wires are cleaned. William Grylls Adams and Richard Evans Day observed the photovoltaic effect in selenium in 1876.[4]
A unified explanation of these phenomena required a theory of solid-state physics which developed greatly in the first half of the 20th Century. In 1878 Edwin Herbert Hall demonstrated the deflection of flowing charge carriers by an applied magnetic field, the Hall effect. The discovery of the electron by J.J. Thomson in 1897 prompted theories of electron-based conduction in solids. Karl Baedeker, by observing a Hall effect with the reverse sign to that in metals, theorized that copper iodide had positive charge carriers. Johan Koenigsberger classified solid materials as metals, insulators and "variable conductors" in 1914 although his student Josef Weiss already introduced the term Halbleiter (semiconductor in modern meaning) in PhD thesis in 1910.[5][6] Felix Bloch published a theory of the movement of electrons through atomic lattices in 1928. In 1930, B. Gudden stated that conductivity in semiconductors was due to minor concentrations of impurities. By 1931, the band theory of conduction had been established by Alan Herries Wilson and the concept of band gaps had been developed. Walter H. Schottky and Nevill Francis Mott developed models of the potential barrier and of the characteristics of a metal–semiconductor junction. By 1938, Boris Davydov had developed a theory of the copper-oxide rectifier, identifying the effect of the p–n junction and the importance of minority carriers and surface states.[7]
Agreement between theoretical predictions (based on developing quantum mechanics) and experimental results was sometimes poor. This was later explained by John Bardeen as due to the extreme "structure sensitive" behavior of semiconductors, whose properties change dramatically based on tiny amounts of impurities.[7] Commercially pure materials of the 1920s containing varying proportions of trace contaminants produced differing experimental results. This spurred the development of improved material refining techniques, culminating in modern semiconductor refineries producing materials with parts-per-trillion purity.
Devices using semiconductors were at first constructed based on empirical knowledge, before semiconductor theory provided a guide to construction of more capable and reliable devices.
Alexander Graham Bell used the light-sensitive property of selenium to transmit sound over a beam of light in 1880. A working solar cell, of low efficiency, was constructed by Charles Fritts in 1883 using a metal plate coated with selenium and a thin layer of gold; the device became commercially useful in photographic light meters in the 1930s.[7] Point-contact microwave detector rectifiers made of lead sulfide were used by Jagadish Chandra Bose in 1904; the cat's-whisker detector using natural galena or other materials became a common device in the development of radio. However, it was somewhat unpredictable in operation and required manual adjustment for best performance. In 1906 H.J. Round observed light emission when electric current passed through silicon carbide crystals, the principle behind the light-emitting diode. Oleg Losev observed similar light emission in 1922 but at the time the effect had no practical use. Power rectifiers, using copper oxide and selenium, were developed in the 1920s and became commercially important as an alternative to vacuum tube rectifiers.[4][7]
The first semiconductor devices used galena, including German physicist Ferdinand Braun's crystal detector in 1874 and Bengali physicist Jagadish Chandra Bose's radio crystal detector in 1901.[8][9]
In the years preceding World War II, infrared detection and communications devices prompted research into lead-sulfide and lead-selenide materials. These devices were used for detecting ships and aircraft, for infrared rangefinders, and for voice communication systems. The point-contact crystal detector became vital for microwave radio systems, since available vacuum tube devices could not serve as detectors above about 4000 MHz; advanced radar systems relied on the fast response of crystal detectors. Considerable research and development of silicon materials occurred during the war to develop detectors of consistent quality.[7]
Early transistors[]
Detector and power rectifiers could not amplify a signal. Many efforts were made to develop a solid-state amplifier and were successful in developing a device called the point contact transistor which could amplify 20db or more.[7] In 1922 Oleg Losev developed two-terminal, negative resistance amplifiers for radio, and he perished in the Siege of Leningrad after successful completion. In 1926 Julius Edgar Lilienfeld patented a device resembling a field-effect transistor, but it was not practical. R. Hilsch and R. W. Pohl in 1938 demonstrated a solid-state amplifier using a structure resembling the control grid of a vacuum tube; although the device displayed power gain, it had a cut-off frequency of one cycle per second, too low for any practical applications, but an effective application of the available theory.[7] At Bell Labs, William Shockley and A. Holden started investigating solid-state amplifiers in 1938. The first p–n junction in silicon was observed by Russell Ohl about 1941, when a specimen was found to be light-sensitive, with a sharp boundary between p-type impurity at one end and n-type at the other. A slice cut from the specimen at the p–n boundary developed a voltage when exposed to light.
The first working transistor was a point-contact transistor invented by John Bardeen, Walter Houser Brattain and William Shockley at Bell Labs in 1947. Shockley had earlier theorized a field-effect amplifier made from germanium and silicon, but he failed to build such a working device, before eventually using germanium to invent the point-contact transistor.[10] In France, during the war, Herbert Mataré had observed amplification between adjacent point contacts on a germanium base. After the war, Mataré's group announced their "Transistron" amplifier only shortly after Bell Labs announced the "transistor".
In 1954, physical chemist Morris Tanenbaum fabricated the first silicon junction transistor at Bell Labs.[11] However, early junction transistors were relatively bulky devices that were difficult to manufacture on a mass-production basis, which limited them to a number of specialised applications.[12]
Silicon semiconductors[]
- See also: Surface passivation and Thermal oxidation
The first silicon semiconductor device was a silicon radio crystal detector, developed by American engineer Greenleaf Whittier Pickard in 1906.[9] In 1940, Russell Ohl discovered the p-n junction and photovoltaic effects in silicon. In 1941, techniques for producing high-purity germanium and silicon crystals were developed for radar microwave detectors during World War II.[8] In 1955, Carl Frosch and Lincoln Derick at Bell Labs accidentally discovered that silicon dioxide (SiO2) could be grown on silicon,[13] and they later proposed this could mask silicon surfaces during diffusion processes in 1958.[14]
In the early years of the semiconductor industry, up until the late 1950s, germanium was the dominant semiconductor material for transistors and other semiconductor devices, rather than silicon. Germanium was initially considered the more effective semiconductor material, as it was able to demonstrate better performance due to higher carrier mobility.[15][16] The relative lack of performance in early silicon semiconductors was due to electrical conductivity being limited by unstable quantum surface states,[17] where electrons are trapped at the surface, due to dangling bonds that occur because unsaturated bonds are present at the surface.[18] This prevented electricity from reliably penetrating the surface to reach the semiconducting silicon layer.[19][20]
A breakthrough in silicon semiconductor technology came with the work of Egyptian engineer Mohamed Atalla, who developed the process of surface passivation by thermal oxidation at Bell Labs in the late 1950s.[18][21][16] He discovered that the formation of a thermally grown silicon dioxide layer greatly reduced the concentration of electronic states at the silicon surface,[21] and that silicon oxide layers could be used to electrically stabilize silicon surfaces.[22] Atalla first published his findings in Bell memos during 1957, and then demonstrated it in 1958.[23][24] This was the first demonstration to show that high-quality silicon dioxide insulator films could be grown thermally on the silicon surface to protect the underlying silicon p-n junction diodes and transistors.[14] Atalla's surface passivation process enabled silicon to surpass the conductivity and performance of germanium, and led to silicon replacing germanium as the dominant semiconductor material.[16][17] Atalla's surface passivation process is considered the most important advance in silicon semiconductor technology, paving the way for the mass-production of silicon semiconductor devices.[25] By the mid-1960s, Atalla's process for oxidized silicon surfaces was used to fabricate virtually all integrated circuits and silicon devices.[26] Surface passivation by thermal oxidation remains a key feature of silicon semiconductor technology.[27]
MOS transistor[]
- See also: List of semiconductor scale examples and Transistor count
In the late 1950s, Mohamed Atalla utilized his surface passivation and thermal oxidation methods to develop the metal–oxide–semiconductor (MOS) process, which he proposed could be used to build the first working silicon field-effect transistor.[19][20] This led to the invention of the MOSFET (MOS field-effect transistor) by Mohamed Atalla and Dawon Kahng in 1959.[28][23] It was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses,[12] With its scalability,[29] and much lower power consumption and higher density than bipolar junction transistors,[30] the MOSFET became the most common type of transistor in computers, electronics,[20] and communications technology such as smartphones.[31] The US Patent and Trademark Office calls the MOSFET a "groundbreaking invention that transformed life and culture around the world".[31]
The CMOS (complementary MOS) process was developed by Chih-Tang Sah and Frank Wanlass at Fairchild Semiconductor in 1963.[32] The first report of a floating-gate MOSFET was made by Dawon Kahng and Simon Sze in 1967.[33] FinFET (fin field-effect transistor), a type of 3D multi-gate MOSFET, was developed by Digh Hisamoto and his team of researchers at Hitachi Central Research Laboratory in 1989.[34][35]
Properties[]
A semiconductor behaves as an insulator at very low temperature, and has an appreciable electrical conductivity at room temperature although much lower conductivity than a conductor.
A semiconductor can be distinguished from a conductor by the fact that, at absolute zero, the uppermost filled electron energy band is fully filled in a semiconductor, but only partially filled in a conductor.
Semiconductor materials do not follow Ohm's law, i.e. the electrical resistance changes with voltage and intensity.
The distinction between a semiconductor and an insulator is slightly more arbitrary. A semiconductor has a band gap which is small enough such that its conduction band is appreciably thermally populated with electrons at room temperature, whilst an insulator has a band gap which is too wide for there to be appreciable thermal electrons in its conduction band at room temperature.
Semiconductor devices are manufactured as single discrete devices or integrated circuits (ICs), which consist of a number—from a few devices to millions—of devices manufactured onto a single semiconductor substrate.
How semiconductors work[]
Operationally, transistors and vacuum tubes have similar functions; they both control the flow of current.
In order to understand how a semiconductor operates, consider a glass container filled with pure water. If a pair of conductive probes are immersed in the water and a DC voltage (below the electrolysis point i.e. breakdown point for water) is applied between them, no current would flow because the water has no charge carriers. Thus, pure water is an insulator. Dissolve a pinch of table salt in the water and conduction begins, because mobile carriers (ions) have been released. Increasing the salt concentration increases the conduction, but not very much. A dry lump of salt is non-conductive, because the charge carriers are immobile.
An absolutely pure silicon crystal is also an insulator, but when an impurity e.g. arsenic is added (called doping) in quantities minute enough not to completely disrupt the regularity of the crystal lattice, it donates free electrons and enables conduction. This is because arsenic atoms have five electrons in their outer shells while silicon atoms have only four. Conduction is possible because a mobile carrier of charge has been introduced, in this case creating n-type silicon ("n" for negative. The electron has a negative charge).
Alternatively, silicon can be doped with boron to make p-type silicon which also conducts. Because boron has only three electrons in its outer shell another kind of charge carrier, called a "hole", is formed in the silicon crystal lattice.
In a vacuum tube, on the other hand, the charge carriers (electrons) are emitted by thermionic emission from a cathode heated by a wire filament. Therefore, vacuum tubes cannot generate holes (positive charge carriers).
Note that charge carriers of the same polarity repel one another so that, in the absence of any force, they are distributed evenly throughout the semiconductor material. However, in an unpowered bipolar transistor (or junction diode) the charge carriers tend to migrate towards a P/N junction, being attracted by their opposite charge carriers on the other side of the junction.
Increasing the doping level increases the semiconductor conductivity, providing that the crystal lattice, overall, remains intact. In a bipolar transistor the emitter has a higher doping level than the base. The ratio of emitter/base doping levels is one of the main factors that dictates the junction transistor's current gain.
The level of doping is extremely low: in the order of parts per one hundred million, and this is the key to semiconductor operation. In metals, the carrier population is extremely high; one charge-carrier per atom. In metals, in order to convert a significant volume of the material into an insulator, the charge carriers must be swept out by applying a voltage. In metals this value of voltage is astronomical; more than enough to destroy the metal before it converts to an insulator. But in lightly-doped semiconductors there is only one mobile charge carrier per millions or more atoms. The level of voltage required to sweep so few charge-carriers out of a significant volume of the material is easily reached. In other words, the electricity in metals is incompressible, like a fluid, while in semiconductors behaves as a compressible gas. Doped semiconductors can be rapidly changed into insulators, while metals cannot.
The above explains conduction in a semiconductor by charge carriers, either electrons or holes, but the essence of bipolar transistor action is the way that electrons/holes seemingly make a prohibited leap across the insulating depletion zone in the reverse-biased base/collector junction under control of the base/emitter voltage. Although a transistor may seem like two interconnected diodes, a bipolar transistor cannot be made simply by connecting two discrete junction diodes together. To produce bipolar transistor action they need to be fabricated on the same crystal, and physically sharing a common and extremely thin base region.
See also[]
- Semiconductor devices
- Transistors
- Diodes
- Microprocessors
- Thermistors
- Solar cells
- Piezoresistors
- Electrical engineering
References[]
- ↑ Shockley, William (1950). Electrons and holes in semiconductors : with applications to transistor electronics. R. E. Krieger Pub. Co. ISBN 978-0-88275-382-9.
- ↑ "Kirj.ee" (PDF).
- ↑ Morris, Peter Robin (July 22, 1990). "A History of the World Semiconductor Industry". IET – via Google Books.
- ↑ 4.0 4.1 Lidia Łukasiak; Andrzej Jakubowski (January 2010). "History of Semiconductors" (PDF). Journal of Telecommunication and Information Technology: 3.
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suggested) (help) - ↑ Busch, G (1989). "Early history of the physics and chemistry of semiconductors-from doubts to fact in a hundred years". European Journal of Physics. 10 (4): 254–264. Bibcode:1989EJPh...10..254B. doi:10.1088/0143-0807/10/4/002.
- ↑ Überlingen.), Josef Weiss (de (July 22, 1910). "Experimentelle Beiträge zur Elektronentheorie aus dem Gebiet der Thermoelektrizität, Inaugural-Dissertation ... von J. Weiss, ..." Druck- und Verlags-Gesellschaft – via Google Books.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 Peter Robin Morris (1990) A History of the World Semiconductor Industry, IET, ISBN 0-86341-227-0, pp. 11–25
- ↑ 8.0 8.1 "Timeline". The Silicon Engine. Computer History Museum. Retrieved 22 August 2019.
- ↑ 9.0 9.1 "1901: Semiconductor Rectifiers Patented as "Cat's Whisker" Detectors". The Silicon Engine. Computer History Museum. Retrieved 23 August 2019.
- ↑ "1947: Invention of the Point-Contact Transistor". The Silicon Engine. Computer History Museum. Retrieved 23 August 2019.
- ↑ "1954: Morris Tanenbaum fabricates the first silicon transistor at Bell Labs". The Silicon Engine. Computer History Museum. Retrieved 23 August 2019.
- ↑ 12.0 12.1 Moskowitz, Sanford L. (2016). Advanced Materials Innovation: Managing Global Technology in the 21st century. John Wiley & Sons. p. 168. ISBN 9780470508923.
- ↑ Bassett, Ross Knox (2007). To the Digital Age: Research Labs, Start-up Companies, and the Rise of MOS Technology. Johns Hopkins University Press. pp. 22–23. ISBN 9780801886393.
- ↑ 14.0 14.1 Saxena, A. (2009). Invention of integrated circuits: untold important facts. International series on advances in solid state electronics and technology. World Scientific. pp. 96–97. ISBN 9789812814456.
- ↑ Dabrowski, Jarek; Müssig, Hans-Joachim (2000). "6.1. Introduction". Silicon Surfaces and Formation of Interfaces: Basic Science in the Industrial World. World Scientific. pp. 344–346. ISBN 9789810232863.
- ↑ 16.0 16.1 16.2 Heywang, W.; Zaininger, K.H. (2013). "2.2. Early history". Silicon: Evolution and Future of a Technology. Springer Science & Business Media. pp. 26–28. ISBN 9783662098974.
- ↑ 17.0 17.1 Feldman, Leonard C. (2001). "Introduction". Fundamental Aspects of Silicon Oxidation. Springer Science & Business Media. pp. 1–11. ISBN 9783540416821.
- ↑ 18.0 18.1 Kooi, E.; Schmitz, A. (2005). "Brief Notes on the History of Gate Dielectrics in MOS Devices". High Dielectric Constant Materials: VLSI MOSFET Applications. Springer Science & Business Media. pp. 33–44. ISBN 9783540210818.
- ↑ 19.0 19.1 "Martin (John) M. Atalla". National Inventors Hall of Fame. 2009. Retrieved 21 June 2013.
- ↑ 20.0 20.1 20.2 "Dawon Kahng". National Inventors Hall of Fame. Retrieved 27 June 2019.
- ↑ 21.0 21.1 Black, Lachlan E. (2016). New Perspectives on Surface Passivation: Understanding the Si-Al2O3 Interface. Springer. p. 17. ISBN 9783319325217.
- ↑ Lécuyer, Christophe; Brock, David C. (2010). Makers of the Microchip: A Documentary History of Fairchild Semiconductor. MIT Press. p. 111. ISBN 9780262294324.
- ↑ 23.0 23.1 Lojek, Bo (2007). History of Semiconductor Engineering. Springer Science & Business Media. pp. 120 & 321-3. ISBN 9783540342588.
- ↑ Bassett, Ross Knox (2007). To the Digital Age: Research Labs, Start-up Companies, and the Rise of MOS Technology. Johns Hopkins University Press. p. 46. ISBN 9780801886393.
- ↑ Sah, Chih-Tang (October 1988). "Evolution of the MOS transistor-from conception to VLSI" (PDF). Proceedings of the IEEE. 76 (10): 1280–1326 (1290). doi:10.1109/5.16328. ISSN 0018-9219.
Those of us active in silicon material and device research during 1956–1960 considered this successful effort by the Bell Labs group led by Atalla to stabilize the silicon surface the most important and significant technology advance, which blazed the trail that led to silicon integrated circuit technology developments in the second phase and volume production in the third phase.
- ↑ Donovan, R. P. (November 1966). "The Oxide-Silicon Interface". Fifth Annual Symposium on the Physics of Failure in Electronics: 199–231. doi:10.1109/IRPS.1966.362364.
- ↑ "Surface Passivation - an overview". ScienceDirect. Retrieved 19 August 2019.
- ↑ "1960 - Metal Oxide Semiconductor (MOS) Transistor Demonstrated". The Silicon Engine. Computer History Museum.
- ↑ Motoyoshi, M. (2009). "Through-Silicon Via (TSV)" (PDF). Proceedings of the IEEE. 97 (1): 43–48. doi:10.1109/JPROC.2008.2007462. ISSN 0018-9219.
- ↑ "Transistors Keep Moore's Law Alive". EETimes. 12 December 2018. Retrieved 18 July 2019.
- ↑ 31.0 31.1 "Remarks by Director Iancu at the 2019 International Intellectual Property Conference". United States Patent and Trademark Office. June 10, 2019. Retrieved 20 July 2019.
- ↑ "1963: Complementary MOS Circuit Configuration is Invented". Computer History Museum. Retrieved 6 July 2019.
- ↑ D. Kahng and S. M. Sze, "A floating gate and its application to memory devices", The Bell System Technical Journal, vol. 46, no. 4, 1967, pp. 1288–1295
- ↑ "IEEE Andrew S. Grove Award Recipients". IEEE Andrew S. Grove Award. Institute of Electrical and Electronics Engineers. Retrieved 4 July 2019.
- ↑ "The Breakthrough Advantage for FPGAs with Tri-Gate Technology" (PDF). Intel. 2014. Retrieved 4 July 2019.
External links[]
- Howstuffworks' semiconductor page
- US Navy Electrical Engineering Training Series
- NSM-Archive Physical Properties of Semiconductors
- Semiconductor Concepts at Hyperphysics
- Principles of Semiconductor Devices by Bart Van Zeghbroeck, University of Colorado
- Semiconductor OneSource Hall of Fame, Glossary
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