 A laboratory-grown synthetic SiCmonocrystal | |
| Names | |
|---|---|
| IUPAC name Methanidylidynesilanylium | |
| Preferred IUPAC name Silicon carbide | |
| Other names Carborundum Moissanite | |
| Identifiers | |
| |
3D model (JSmol) | |
| ChEBI | |
| ChemSpider |
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| ECHA InfoCard | 100.006.357 |
| EC Number |
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| 13642 | |
| MeSH | Silicon+carbide |
| RTECS number |
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| UNII | |
| |
| |
| Properties | |
| SiC | |
| Molar mass | 40.096 g/mol |
| Appearance | Yellow to green to bluish-black, iridescent crystals[1] |
| Density | 3.16 g⋅cm−3 (hex.)[2] |
| Melting point | 2,830 °C (5,130 °F; 3,100 K)[2] (decomposes) |
| Solubility | Insoluble in water, soluble in molten alkalis and molten iron[3] |
| Electron mobility | ~900 cm2/(V⋅s) (all polytypes) |
| −12.8 × 10−6 cm3/mol[4] | |
Refractive index (nD) | 2.55 (infrared; all polytypes)[5] |
| Hazards | |
| GHS labelling:fibres[6] | |
 | |
| Danger | |
| H350i | |
| P201,P202,P260,P261,P264,P270,P271,P280,P281,P302+P352,P304+P340,P305+P351+P338,P308+P313,P312,P314,P321,P332+P313,P337+P313,P362,P403+P233,P405,P501 | |
| NFPA 704 (fire diamond) | |
| NIOSH (US health exposure limits): | |
PEL (Permissible) | TWA 15 mg/m3 (total) TWA 5 mg/m3 (resp)[1] |
REL (Recommended) | TWA 10 mg/m3 (total) TWA 5 mg/m3 (resp)[1] |
IDLH (Immediate danger) | N.D.[1] |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Silicon carbide (SiC), also known ascarborundum (/ˌkɑːrbəˈrʌndəm/), is a hard chemical compound containingsilicon andcarbon. A wide bandgapsemiconductor, it occurs in nature as the extremely rare mineralmoissanite, but has been mass-produced as a powder and crystal since 1893 for use as anabrasive. Grains of silicon carbide can be bonded together bysintering to form very hardceramics that are widely used in applications requiring high endurance, such as car brakes, car clutches andceramic plates inbulletproof vests. Large single crystals of silicon carbide can be grown by theLely method and they can be cut into gems known as synthetic moissanite.
Electronic applications of silicon carbide such aslight-emitting diodes (LEDs) anddetectors in early radios were first demonstrated around 1907. SiC is used in semiconductor electronics devices that operate at high temperatures or high voltages, or both.
Naturally occurringmoissanite is found in only minute quantities in certain types ofmeteorite,corundum deposits, andkimberlite. Virtually all the silicon carbide sold in the world, including moissanite jewels, issynthetic.
Natural moissanite was first found in 1893 as a small component of theCanyon Diablo meteorite inArizona byFerdinand Henri Moissan, after whom the material was named in 1905.[7] Moissan's discovery of naturally occurring SiC was initially disputed because his sample may have been contaminated by silicon carbidesaw blades that were already on the market at that time.[8]
While rare on Earth, silicon carbide is remarkably common in space. It is a common form ofstardust found aroundcarbon-rich stars, and examples of this stardust have been found in pristine condition in primitive (unaltered) meteorites. The silicon carbide found in space and meteorites is almost exclusively thebeta-polymorph. Analysis of SiC grains found in theMurchison meteorite, acarbonaceous chondrite meteorite, has revealed anomalous isotopic ratios of carbon and silicon, indicating that these grains originated outside theSolar System.[9]
Non-systematic, less-recognized, and often unverified syntheses of silicon carbide include:
Wide-scale production is credited toEdward Goodrich Acheson in 1891.[11] Acheson was attempting to prepare artificial diamonds when he heated a mixture of clay (aluminium silicate) and powderedcoke (carbon) in an iron bowl. He called the blue crystals that formedcarborundum, believing it to be a new compound of carbon and aluminium, similar tocorundum.Henri Moissan also synthesized SiC by several routes, including dissolution of carbon in molten silicon, melting a mixture of calcium carbide and silica, and reducing silica with carbon in an electric furnace.
Acheson patented the method for making silicon carbide powder on February 28, 1893.[12] Acheson also developed the electric batchfurnace by which SiC is still made today and formed the Carborundum Company to manufacture bulk SiC, initially for use as an abrasive.[13] In 1900 the company settled with theElectric Smelting and Aluminum Company when a judge's decision gave "priority broadly" to its founders "for reducing ores and other substances by the incandescent method".[14]
The first use of SiC was as an abrasive. This was followed by electronic applications. In the beginning of the 20th century, silicon carbide was used as a detector in the first radios.[15] In 1907Henry Joseph Round produced the first LED by applying a voltage to a SiC crystal and observing yellow, green and orange emission at the cathode. The effect was later rediscovered byO.V. Losev in theSoviet Union, in 1923.[16]
Because natural moissanite is extremely scarce, most silicon carbide is synthetic. Silicon carbide is used as an abrasive, as well as asemiconductor anddiamond simulant of gem quality. The simplest process to manufacture silicon carbide is to combinesilicasand andcarbon in anAcheson graphite electric resistance furnace at a high temperature, between 1,600 °C (2,910 °F) and 2,500 °C (4,530 °F). Fine SiO2 particles in plant material (e.g. rice husks) can be converted to SiC by heating in the excess carbon from the organic material.[17] Thesilica fume, which is a byproduct of producing silicon metal and ferrosilicon alloys, can also be converted to SiC by heating with graphite at 1,500 °C (2,730 °F).[18]
The material formed in the Acheson furnace varies in purity, according to its distance from thegraphiteresistorheat source. Colorless, pale yellow, and green crystals have the highest purity and are found closest to the resistor. The color changes to blue and black at greater distance from the resistor, and these darker crystals are less pure. Nitrogen and aluminium are common impurities, and they affect the electrical conductivity of SiC.[19]
Pure silicon carbide can be made by theLely process,[20] in which SiC powder is sublimed into high-temperature species of silicon, carbon, silicon dicarbide (SiC2), and disilicon carbide (Si2C) in anargon gas ambient at 2,500 °C and redeposited into flake-like single crystals,[21] sized up to 2 × 2 cm, at a slightly colder substrate. This process yields high-quality single crystals, mostly of 6H-SiC phase (because of high growth temperature).
A modified Lely process involvinginduction heating in graphitecrucibles yields even larger single crystals of 4 inches (10 cm) in diameter, having a section 81 times larger compared to the conventional Lely process.[22] Silicon carbide wafers are often grown using this method, known in the industry asphysical vapor transport with a seed wafer made of SiC. SiC powder is heated until it sublimes, and then the SiC vapor cools and deposits below the seed crystal.[23][24]
Cubic SiC is usually grown by the more expensive process ofchemical vapor deposition (CVD) of silane, hydrogen, and nitrogen.[19][25] Homoepitaxial and heteroepitaxial SiC layers can be grown employing both gas and liquid phase approaches.[26]
To form complexly shaped SiC,preceramic polymers can be used as precursors which form the ceramic product throughpyrolysis at temperatures in the range 1,000–1,100 °C.[27] Precursor materials to obtain silicon carbide in such a manner include polycarbosilanes,poly(methylsilyne) and polysilazanes.[28] Silicon carbide materials obtained through the pyrolysis ofpreceramic polymers are known aspolymer derived ceramics or PDCs. Pyrolysis ofpreceramic polymers is most often conducted under aninert atmosphere at relatively low temperatures. Relative to the CVD process, the pyrolysis method is advantageous because the polymer can be formed into various shapes prior to thermalization into the ceramic.[29][30][31][32]
SiC can also be made into wafers by cutting a single crystal either using a diamond wire saw or by using a laser. SiC is a useful semiconductor used in power electronics.[33]
 |  |  |
| (β)3C-SiC | 4H-SiC | (α)6H-SiC |
Silicon carbide exists in about 250 crystalline forms.[34] Through inert atmospheric pyrolysis ofpreceramic polymers, silicon carbide in a glassy amorphous form is also produced.[27] The polymorphism of SiC is characterized by a large family of similar crystalline structures called polytypes. They are variations of the same chemical compound that are identical in two dimensions and differ in the third. Thus, they can be viewed as layers stacked in a certain sequence.[35]
Alpha silicon carbide (α-SiC) is the most commonly encounteredpolymorph, and is formed at temperatures greater than 1,700 °C and has ahexagonalcrystal structure (similar toWurtzite). The beta modification (β-SiC), with azinc blende crystal structure (similar todiamond), is formed at temperatures below 1,700 °C.[36] Until recently, the beta form has had relatively few commercial uses, although there is now increasing interest in its use as a support forheterogeneous catalysts, owing to its higher surface area compared to the alpha form.
| Polytype | 3C (β) | 4H | 6H (α) |
|---|---|---|---|
| Crystal structure | Zinc blende (cubic) | Hexagonal | Hexagonal |
| Space group | T2d-F43m | C46v-P63mc | C46v-P63mc |
| Pearson symbol | cF8 | hP8 | hP12 |
| Lattice constants (Å) | 4.3596 | 3.0730; 10.053 | 3.0810; 15.12 |
| Density (g/cm3) | 3.21 | 3.21 | 3.21 |
| Bandgap (eV) | 2.36 | 3.23 | 3.05 |
| Bulk modulus (GPa) | 250 | 220 | 220 |
| Thermal conductivity (W⋅m−1⋅K−1) @300 K (see[37][38] for temp. dependence) | 320 | 348 | 325 |
| Thermal Expansion Coefficient (10−6 K−1) @300 K (see[39] for temp. dependence) | -- | 2.28 (⊥c); 2.49 (∥c) | 2.25 |
Pure SiC is colorless. The brown to black color of the industrial product results fromiron impurities.[40] The rainbow-like luster of the crystals is due to thethin-film interference of apassivation layer ofsilicon dioxide that forms on the surface.
The high sublimation temperature of SiC (approximately 2,700 °C) makes it useful forbearings and furnace parts. Silicon carbide does not melt but begins to sublimate near 2,700 °C like graphite, having an appreciable vapor pressure near that temperature. It is also highly inert chemically, partly due to the formation of a thin passivated layer of SiO2. There is currently much interest in its use as asemiconductor material in electronics, where its high thermal conductivity, highelectric field breakdown strength and high maximumcurrent density make it more promising than silicon for high-powered devices.[41] SiC has a very lowcoefficient of thermal expansion of about 2.3 × 10−6 K−1 near 300 K (for 4H and 6H SiC) and experiences nophase transitions in the temperature range 5 K to 340 K that would cause discontinuities in the thermal expansion coefficient.[19][39]
Silicon carbide is asemiconductor, which can be doped n-type bynitrogen orphosphorus and p-type byberyllium,boron,aluminium, orgallium.[5] Metallic conductivity has been achieved by heavy doping with boron, aluminium, or nitrogen.
Superconductivity has been detected in 3C-SiC:Al, 3C-SiC:B and 6H-SiC:B at similar temperatures ~1.5 K.[36][42] A crucial difference is however observed for the magnetic field behavior between aluminium and boron doping: 3C-SiC:Al istype-II. In contrast, 3C-SiC:B istype-I, as is 6H-SiC:B. Thus, the superconducting properties seem to depend more on dopant (B vs. Al) than on polytype (3C- vs 6H-). In an attempt to explain this dependence, it was noted that B substitutes at C sites in SiC, but Al substitutes at Si sites. Therefore, Al and B "see" different environments, in both polytypes.[43]
_disk.jpg)
In manufacturing, it is used for its hardness inabrasive machining processes such asgrinding,honing,water-jet cutting andsandblasting. SiC provides a much sharper and harder alternative for sand blasting as compared toaluminium oxide. Particles of silicon carbide are laminated to paper to createsandpapers and the grip tape onskateboards.[44]
In the arts, silicon carbide is a popular abrasive in modernlapidary due to the durability and low cost of the material.
In 1982, an exceptionally strong composite ofaluminium oxide and silicon carbidewhiskers was discovered. Development of this laboratory-produced composite to a commercial product took only three years. In 1985, the first commercial cutting tools made from this alumina and silicon carbide whisker-reinforced composite were introduced into the market.[45]
.jpg)
In the 1980s and 1990s, silicon carbide was studied in several research programs for high-temperature gas turbines inEurope,Japan, and theUnited States. The components were intended to replacenickelsuperalloyturbine blades or nozzle vanes.[46] However, none of these projects resulted in a production quantity, mainly because of its low impact resistance and its low fracturetoughness.[47]
Like other hard ceramics (namely alumina andboron carbide), silicon carbide is used incomposite armor (e.g.Chobham armor), and in ceramic plates in bulletproof vests.Dragon Skin, which was produced byPinnacle Armor, used disks of silicon carbide.[48] Improved fracture toughness in SiC armor can be facilitated through the phenomenon ofabnormal grain growth or AGG. The growth of abnormally long silicon carbide grains may serve to impart a toughening effect through crack-wake bridging, similar to whisker reinforcement. SimilarAGG-toughening effects have been reported inSilicon nitride (Si3N4).[49]
Silicon carbide is used as a support and shelving material in high-temperature kilns such as for firing ceramics, glass fusing, or glass casting. SiC kiln shelves are considerably lighter and more durable than traditional alumina shelves.[50]
In December 2015, infusion of silicon carbide nano-particles in moltenmagnesium was mentioned as a way to produce a new strong and plastic alloy suitable for use in aeronautics, aerospace, automobile, and micro-electronics.[51]
Silicon-infiltratedcarbon-carbon composite is used for high-performance "ceramic"brake discs, as they can withstand extreme temperatures. The silicon reacts with the graphite in the carbon-carbon composite to become carbon-fiber-reinforced silicon carbide (C/SiC). These brake discs are used on some road-going sports cars, supercars, as well as other performance cars including thePorsche Carrera GT, theBugatti Veyron, theChevrolet Corvette ZR1, theMcLaren P1,[52]Bentley,Ferrari,Lamborghini and some specific high-performanceAudi cars. Silicon carbide is also used in asintered form fordiesel particulate filters.[53] It is also used as an oil additive[dubious –discuss][clarification needed] to reduce friction, emissions, and harmonics.[54][55]
SiC is used in crucibles for holding melting metal in small and large foundry applications.[56][57]
The earliest electrical application of SiC was as asurge protection inlightning arresters in electric power systems. These devices must exhibit highresistance until thevoltage across them reaches a certain threshold VT at which point their resistance must drop to a lower level and maintain this level until the applied voltage drops below VT flushing current into the ground.[58]
It was recognized early on[when?] that SiC had such avoltage-dependent resistance, and so columns of SiC pellets were connected between high-voltagepower lines and the earth. When alightning strike to the line raises the line voltage sufficiently, the SiC column will conduct, allowing strike current to pass harmlessly to the earth instead of along the power line. The SiC columns proved to conduct significantly at normal power-line operating voltages and thus had to be placedin series with aspark gap. This spark gap isionized and rendered conductive when lightning raises the voltage of the power line conductor, thus effectively connecting the SiC column between the power conductor and the earth. Spark gaps used in lightning arresters are unreliable, either failing to strike an arc when needed or failing to turn off afterwards, in the latter case due to material failure or contamination by dust or salt. Usage of SiC columns was originally intended to eliminate the need for the spark gap in lightning arresters. Gapped SiC arresters were used for lightning-protection and sold under theGE andWestinghouse brand names, among others. The gapped SiC arrester has been largely displaced by no-gapvaristors that use columns ofzinc oxide pellets.[59]
Silicon carbide was the first commercially important semiconductor material. Acrystal radio "carborundum" (synthetic silicon carbide) detector diode was patented byHenry Harrison Chase Dunwoody in 1906. It found much early use in shipboard receivers.
In 1993, the silicon carbide was considered asemiconductor in both research and earlymass production providing advantages for fast, high-temperature and/or high-voltage devices. The first devices available wereSchottky diodes, followed byjunction-gate FETs andMOSFETs for high-power switching.Bipolar transistors andthyristors were described.[41]
A major problem for SiC commercialization has been the elimination of defects: edge dislocations, screw dislocations (both hollow and closed core), triangular defects and basal plane dislocations.[60] As a result, devices made of SiC crystals initially displayed poor reverse blocking performance, though researchers have been tentatively finding solutions to improve the breakdown performance.[61]Apart from crystal quality, problems with the interface of SiC with silicon dioxide have hampered the development of SiC-based power MOSFETs andinsulated-gate bipolar transistors. Although the mechanism is still unclear,nitriding has dramatically reduced the defects causing the interface problems.[62]
In 2008, the first commercialJFETs rated at 1,200 V were introduced to the market,[63] followed in 2011 by the first commercial MOSFETs rated at 1200 V. JFETs are now available rated 650 V to 1,700 V with resistance as low as 25 mΩ. Beside SiC switches and SiC Schottky diodes (also Schottky barrier diode,SBD) in the popular TO-247 andTO-220 packages, companies started even earlier to implement the bare chips into theirpower electronic modules.
SiC SBD diodes found wide market spread being used inPFC circuits andIGBTpower modules.[64]Conferences such as theInternational Conference on Integrated Power Electronics Systems (CIPS) report regularly about the technological progress of SiC power devices.Major challenges for fully unleashing the capabilities of SiC power devices are:
Beginning withTesla Model 3 theinverters in the drive unit use 24 pairs of silicon carbide (SiC)MOSFET chips rated for 650 volts each. Silicon carbide in this instance gave Tesla a significant advantage over chips made of silicon in terms of size and weight. A number of automobile manufacturers are planning to incorporate silicon carbide into power electronic devices in their products. A significant increase in production of silicon carbide is projected, beginning with a large plant opened 2022 byWolfspeed, in upstate New York.[67][68]
The phenomenon ofelectroluminescence was discovered in 1907 using silicon carbide and some of the first commercialLEDs were based on this material. When General Electric of America introduced its SSL-1 Solid State Lamp in March 1967, using a tiny chip of semi-conducting SiC to emit a point of yellow light, it was then the world's brightest LED.[69] By 1970 it had been usurped by brighter red LEDs, but yellow LEDs made from 3C-SiC continued to be manufactured in the Soviet Union in the 1970s[70] andblue LEDs (6H-SiC) worldwide in the 1980s.[71]
Carbide LED production soon stopped when a different material,gallium nitride, showed 10–100 times brighter emission. This difference in efficiency is due to the unfavorableindirect bandgap of SiC, whereas GaN has adirect bandgap which favors light emission. However, SiC is still one of the important LED components: It is a popular substrate for growing GaN devices, and it also serves as a heat spreader in high-power LEDs.[71]
The low thermal expansion coefficient,[39] high hardness, rigidity and thermal conductivity make silicon carbide a desirablemirror material forastronomical telescopes. The growth technology (chemical vapor deposition) has been scaled up to produce disks of polycrystalline silicon carbide up to 3.5 m (11 ft) in diameter, and several telescopes like theHerschel Space Telescope are already equipped with SiC optics,[72][73] as well theGaiaspace observatory spacecraft subsystems are mounted on a rigid silicon carbide frame, which provides a stable structure that will not expand or contract due to heat.
Silicon carbide fibers are used to measure gas temperatures in an optical technique called thin-filament pyrometry. It involves the placement of a thin filament in a hot gas stream. Radiative emissions from the filament can be correlated with filament temperature. Filaments are SiC fibers with a diameter of 15 micrometers, about one fifth that of a human hair. Because the fibers are so thin, they do little to disturb the flame and their temperature remains close to that of the local gas. Temperatures of about 800–2,500 K can be measured.[74][75]
References to silicon carbide heating elements exist from the early 20th century when they were produced by Acheson's Carborundum Co. in the U.S. and EKL in Berlin. Silicon carbide offered increasedoperating temperatures compared with metallic heaters. Silicon carbide elements are used today in the melting of glass and non-ferrous metal,heat treatment of metals,float glass production, production of ceramics and electronics components, igniters inpilot lights for gas heaters, etc.[76]
The outer thermal protection layer of NASA's LOFTID inflatable heat shield incorporates a woven ceramic made from silicon carbide, with fiber of such small diameter that it can be bundled and spun into a yarn.[77]
Due to SiC's exceptionalneutron absorption capability, it is used as fuel cladding innuclear reactors and asnuclear waste containment material.[78] It is also used in producing radiation detectors for monitoring radiation levels in nuclear facilities, environmental monitoring, andmedical imaging.[79] Again, SiC sensors and electronics for nuclear reactor applications are being developed potentially for futureMartian nuclear power and the emerging terrestrial micro nuclear power plants.[80]
Silicon carbide is an important material inTRISO-coated fuel particles, the type ofnuclear fuel found inhigh temperature gas cooled reactors such as thePebble Bed Reactor. A layer of silicon carbide gives coated fuel particles structural support and is the main diffusion barrier to the release of fission products.[81]
Silicon carbidecomposite material has been investigated for use as a replacement forZircaloy cladding inlight water reactors. One of the reasons for this investigation is that, Zircaloy experiences hydrogen embrittlement as a consequence of the corrosion reaction with water. This produces a reduction in fracture toughness with increasing volumetric fraction of radial hydrides. This phenomenon increases drastically with increasing temperature to the detriment of the material.[82] Silicon carbide cladding does not experience this same mechanical degradation, but instead retains strength properties with increasing temperature. The composite consists of SiC fibers wrapped around a SiC inner layer and surrounded by an SiC outer layer.[83] Problems have been reported with the ability to join the pieces of the SiC composite.[84]
As agemstone used injewelry, silicon carbide is called "synthetic moissanite" or just "moissanite" after the mineral name. Moissanite is similar todiamond in several important respects: it is transparent and hard (9–9.5 on theMohs scale, compared to 10 for diamond), with arefractive index between 2.65 and 2.69 (compared to 2.42 for diamond). Moissanite is somewhat harder than commoncubic zirconia. Unlike diamond, moissanite can be stronglybirefringent. For this reason, moissanite jewels are cut along theoptic axis of the crystal to minimize birefringent effects. It is lighter (density 3.21 g/cm3 vs. 3.53 g/cm3), and much more resistant to heat than diamond. This results in a stone of higherluster, sharper facets, and good resilience. Loose moissanite stones may be placed directly into wax ring moulds for lost-wax casting, as can diamond,[85] as moissanite remains undamaged by temperatures up to 1,800 °C (3,270 °F). Moissanite has become popular as a diamond substitute, and may be misidentified as diamond, since itsthermal conductivity is closer to diamond than any other substitute. Many thermal diamond-testing devices cannot distinguish moissanite from diamond, but the gem is distinct in itsbirefringence and a very slight green or yellow fluorescence under ultraviolet light. Some moissanite stones also have curved, string-like inclusions, which diamonds never have.[86]
Silicon carbide, dissolved in abasic oxygen furnace used for makingsteel, acts as afuel. The additional energy liberated allows the furnace to process more scrap with the same charge of hot metal. It can also be used to raisetap temperatures and adjust the carbon and silicon content. Silicon carbide is cheaper than a combination offerrosilicon and carbon, produces cleaner steel and lower emissions due to low levels oftrace elements, has a low gas content, and does not lower the temperature of steel.[87]
The natural resistance to oxidation exhibited by silicon carbide, as well as the discovery of new ways to synthesize the cubic β-SiC form, with its larger surface area, has led to significant interest in its use as a heterogeneouscatalyst support. This form has already been employed as a catalyst support for the oxidation ofhydrocarbons, such as n-butane, tomaleic anhydride.[88][89]
Silicon carbide is used incarborundum printmaking – acollagraphprintmaking technique. Carborundum grit is applied in a paste to the surface of an aluminium plate. When the paste is dry, ink is applied and trapped in its granular surface, then wiped from the bare areas of the plate. The ink plate is then printed onto paper in a rolling-bed press used forintaglio printmaking. The result is a print of painted marks embossed into the paper.
Carborundum grit is also used in stone Lithography. Its uniform particle size allows it to be used to "Grain" a stone which removes the previous image. In a similar process to sanding, coarser grit Carborundum is applied to the stone and worked with aLevigator, typically a round plate eccentric on a perpendicular shaft, then gradually finer and finer grit is applied until the stone is clean. This creates a grease sensitive surface.[90]
Silicon carbide can be used in the production ofgraphene because of its chemical properties that promote the production of graphene on the surface of SiC nanostructures.
When it comes to its production, silicon is used primarily as a substrate to grow the graphene. But there are actually several methods that can be used to grow the graphene on the silicon carbide. The confinement controlled sublimation (CCS) growth method consists of a SiC chip that is heated under vacuum with graphite. Then the vacuum is released very gradually to control the growth of graphene. This method yields the highest quality graphene layers. But other methods have been reported to yield the same product as well.
Another way of growing graphene would be thermally decomposing SiC at a high temperature within a vacuum.[91] But, this method turns out to yield graphene layers that contain smaller grains within the layers.[92] So, there have been efforts to improve the quality and yield of graphene. One such method is to performex situgraphitization of silicon terminated SiC in an atmosphere consisting of argon. This method has proved to yield layers of graphene with larger domain sizes than the layer that would be attainable via other methods. This new method can be very viable to make higher quality graphene for a multitude of technological applications.
When it comes to understanding how or when to use these methods of graphene production, most of them mainly produce or grow this graphene on the SiC within a growth enabling environment. It is utilized most often at rather higher temperatures (such as 1,300 °C) because of SiC thermal properties.[93] However, there have been certain procedures that have been performed and studied that could potentially yield methods that use lower temperatures to help manufacture graphene. More specifically this different approach to graphene growth has been observed to produce graphene within a temperature environment of around 750 °C. This method entails the combination of certain methods like chemical vapor deposition (CVD) and surface segregation. And when it comes to the substrate, the procedure would consist of coating a SiC substrate with thin films of a transition metal. And after the rapid heat treating of this substance, the carbon atoms would then become more abundant at the surface interface of the transition metal film which would then yield graphene. And this process was found to yield graphene layers that were more continuous throughout the substrate surface.[94]
Silicon carbide can host point defects in the crystal lattice, which are known ascolor centers. These defects can produce single photons on demand and thus serve as a platform forsingle-photon source.[95] Such a device is a fundamental resource for many emerging applications of quantum information science. If one pumps a color center via an external optical source or electric current, the color center will be brought to the excited state and then relax with the emission of one photon.[96][97]
One well known point defect in silicon carbide is the divacancy which has a similar electronic structure as thenitrogen-vacancy center in diamond. In 4H-SiC, the divacancy has four different configurations which correspond to four zero-phonon lines (ZPL). These ZPL values are written using the notation VSi-VC and the unit eV: hh(1.095), kk(1.096), kh(1.119), and hk(1.150).[98]
Silicon carbide is used in the manufacturing of fishing guides because of its durability and wear resistance.[99] Silicon Carbide rings are fit into a guide frame, typically made from stainless steel or titanium which keep the line from touching the rod blank. The rings provide a low friction surface which improves casting distance while providing adequate hardness that prevents abrasion from braided fishing line.[100]
Silicon carbide is used as a raw ingredient in someglazes applied to ceramics. At high temperatures it can reduce metal oxides formingsilica and carbon dioxide. This can be used to make the glaze foam and crater due to the evolved carbon dioxide gas, or to reduce the colorant oxides and achieve colors such ascopper reds otherwise only possible in a fuel poweredreduction firing in an electric kiln.[101]
full SiC power module, in its Model 3. ... STMicroelectronics ... Tesla inverter ... 24 1-in-1 power modules ... module contains twoSiC MOSFETs
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