Editing Silicon (section)

===Electronics===
{{Main|Semiconductor device fabrication}}
{{Further|Semiconductor industry}}
[[File:Silicon wafer with mirror finish.jpg|thumb|upright|Silicon wafer with mirror finish]]

Most elemental silicon produced remains as a ferrosilicon alloy, and only approximately 20% is refined to metallurgical grade purity (a total of 1.3–1.5 million metric tons/year). An estimated 15% of the world production of metallurgical grade silicon is further refined to semiconductor purity.<ref name="USGS" /> This typically is the "nine-9" or 99.9999999% purity,<ref>"Semi" SemiSource 2006: A supplement to Semiconductor International. December 2005. Reference Section: ''How to Make a Chip.'' Adapted from Design News. Reed Electronics Group.</ref> nearly defect-free single [[crystalline]] material.<ref>SemiSource 2006: A supplement to Semiconductor International. December 2005. Reference Section: ''How to Make a Chip.'' Adapted from Design News. Reed Electronics Group.</ref>

[[Monocrystalline silicon]] of such purity is usually produced by the [[Czochralski process]], and is used to produce [[Wafer (electronics)|silicon wafers]] used in the [[semiconductor industry]], in electronics, and in some high-cost and high-efficiency [[photovoltaic]] applications.<ref name="Ullmann590">{{harvnb|Zulehner|Neuer|Rau|p=590}}</ref> Pure silicon is an [[intrinsic semiconductor]], which means that unlike metals, it conducts [[electron hole]]s and electrons released from atoms by heat; silicon's [[electrical conductivity]] increases with higher temperatures. Pure silicon has too low a conductivity (i.e., too high a [[resistivity]]) to be used as a circuit element in electronics. In practice, pure silicon is [[doping (semiconductors)|doped]] with small concentrations of certain other elements, which greatly increase its conductivity and adjust its electrical response by controlling the number and charge ([[electron hole|positive]] or [[electron|negative]]) of activated carriers. Such control is necessary for [[transistor]]s, [[solar cell]]s, [[semiconductor detector]]s, and other [[semiconductor device]]s used in the computer industry and other technical applications.<ref name="Ullmann573">{{harvnb|Zulehner|Neuer|Rau|p=573}}</ref> In [[silicon photonics]], silicon may be used as a continuous wave [[Raman laser]] medium to produce coherent light.<ref name="dekker_2008">{{cite journal |title=Ultrafast nonlinear all-optical processes in silicon-on-insulator waveguides |journal=[[Journal of Physics D]] |year=2008 |volume=40 |issue=14 |page=R249–R271 |doi=10.1088/0022-3727/40/14/r01 |bibcode=2007JPhD...40..249D |last1=Dekker |first1=R |last2=Usechak |first2=N |last3=Först |first3=M |last4=Driessen |first4=A |s2cid=123008652 |url=https://ris.utwente.nl/ws/files/6730038/Dekker_R._Journ._Appl._Phys__Juni_2007.pdf |access-date=2024-04-15 |archive-date=2024-04-16 |archive-url=https://web.archive.org/web/20240416161929/https://ris.utwente.nl/ws/files/6730038/Dekker_R._Journ._Appl._Phys__Juni_2007.pdf |url-status=dead }}</ref>

In common [[integrated circuit]]s, a wafer of monocrystalline silicon serves as a mechanical support for the circuits, which are created by doping and insulated from each other by thin layers of [[silicon dioxide|silicon oxide]], an insulator that is easily produced on Si surfaces by processes of [[thermal oxidation]] or [[LOCOS|local oxidation (LOCOS)]], which involve exposing the element to oxygen under the proper conditions that can be predicted by the [[Deal–Grove model]]. Silicon has become the most popular material for both high power semiconductors and integrated circuits because it can withstand the highest temperatures and greatest electrical activity without suffering [[avalanche breakdown]] (an [[electron avalanche]] is created when heat produces free electrons and holes, which in turn pass more current, which produces more heat). In addition, the insulating oxide of silicon is not soluble in water, which gives it an advantage over [[germanium]] (an element with similar properties which can also be used in semiconductor devices) in certain fabrication techniques.<ref>[http://www.mpoweruk.com/semiconductors.htm Semiconductors Without the Quantum Physics] {{Webarchive|url=https://web.archive.org/web/20210813034833/https://mpoweruk.com/semiconductors.htm |date=2021-08-13 }}. Electropaedia</ref>

Monocrystalline silicon is expensive to produce, and is usually justified only in production of integrated circuits, where tiny crystal imperfections can interfere with tiny circuit paths. For other uses, other types of pure silicon may be employed. These include [[hydrogenated amorphous silicon]] and upgraded metallurgical-grade silicon (UMG-Si) used in the production of low-cost, [[large-area electronics]] in applications such as [[liquid crystal display]]s and of large-area, low-cost, thin-film [[solar cells]]. Such semiconductor grades of silicon are either slightly less pure or polycrystalline rather than monocrystalline, and are produced in comparable quantities as the monocrystalline silicon: 75,000 to 150,000 metric tons per year. The market for the lesser grade is growing more quickly than for monocrystalline silicon. By 2013, polycrystalline silicon production, used mostly in solar cells, was projected to reach 200,000 metric tons per year, while monocrystalline semiconductor grade silicon was expected to remain less than 50,000 tons per year.<ref name="USGS">Corathers, Lisa A. [http://minerals.usgs.gov/minerals/pubs/commodity/silicon/myb1-2009-simet.pdf 2009 Minerals Yearbook]. USGS</ref>