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69-469: Indium arsenide is similar in properties to gallium arsenide and is a direct bandgap material, with a bandgap of 0.35 eV at room temperature. Indium arsenide is used for the construction of infrared detectors , for the wavelength range of 1.0–3.8 μm. The detectors are usually photovoltaic photodiodes . Cryogenically cooled detectors have lower noise, but InAs detectors can be used in higher-power applications at room temperature as well. Indium arsenide

138-522: A carcinogen , as do IARC and ECA , and it is considered a known carcinogen in animals. On the other hand, a 2013 review (funded by industry) argued against these classifications, saying that when rats or mice inhale fine GaAs powders (as in previous studies), they get cancer from the resulting lung irritation and inflammation, rather than from a primary carcinogenic effect of the GaAs itself—and that, moreover, fine GaAs powders are unlikely to be created in

207-404: A direct band gap , which means that it can be used to absorb and emit light efficiently. Silicon has an indirect band gap and so is relatively poor at emitting light. As a wide direct band gap material with resulting resistance to radiation damage, GaAs is an excellent material for outer space electronics and optical windows in high power applications. Because of its wide band gap, pure GaAs

276-430: A monopropellant and an oxidizer in rocketry . Hydrogen peroxide is a reactive oxygen species and the simplest peroxide , a compound having an oxygen–oxygen single bond . It decomposes slowly into water and elemental oxygen when exposed to light, and rapidly in the presence of organic or reactive compounds. It is typically stored with a stabilizer in a weakly acidic solution in an opaque bottle. Hydrogen peroxide

345-507: A Δ H of –2884.5  kJ / kg and a Δ S of 70.5 J/(mol·K): The rate of decomposition increases with rise in temperature, concentration, and pH . H 2 O 2 is unstable under alkaline conditions. Decomposition is catalysed by various redox-active ions or compounds, including most transition metals and their compounds (e.g. manganese dioxide ( MnO 2 ), silver , and platinum ). The redox properties of hydrogen peroxide depend on pH. In acidic solutions, H 2 O 2

414-422: A 1952 publication. Commercial production of its monocrystals commenced in 1954, and more studies followed in the 1950s. First infrared LEDs were made in 1962. In the compound, gallium has a +3 oxidation state . Gallium arsenide single crystals can be prepared by three industrial processes: Alternative methods for producing films of GaAs include: Oxidation of GaAs occurs in air, degrading performance of

483-408: A fast CMOS structure, GaAs circuits must use logic styles which have much higher power consumption; this has made GaAs logic circuits unable to compete with silicon logic circuits. For manufacturing solar cells, silicon has relatively low absorptivity for sunlight, meaning about 100 micrometers of Si is needed to absorb most sunlight. Such a layer is relatively robust and easy to handle. In contrast,

552-431: A solar cell with 33.3% efficiency based on inverted metamorphic multi-junction (IMM) technology. In IMM, the lattice-matched (same lattice parameters) materials are grown first, followed by mismatched materials. The top cell, GaInP, is grown first and lattice matched to the GaAs substrate, followed by a layer of either GaAs or GaInAs with a minimal mismatch, and the last layer has the greatest lattice mismatch. After growth,

621-510: A solar cell, and thus a smaller (and therefore less expensive) GaAs solar cell is needed to achieve the same results. Concentrator systems have the highest efficiency of existing photovoltaics. So, technologies such as concentrator photovoltaics and methods in development to lower epitaxial growth and substrate costs could lead to a reduction in the cost of GaAs solar cells and forge a path for use in terrestrial applications. GaAs has been used to produce near-infrared laser diodes since 1962. It

690-482: A suitable material for the rapidly developing field of nanoelectronics . Naturally, a GaAs surface cannot withstand the high temperatures needed for diffusion; however a viable and actively pursued alternative as of the 1980s was ion implantation. The second major advantage of Si is the existence of a native oxide ( silicon dioxide , SiO 2 ), which is used as an insulator . Silicon dioxide can be incorporated onto silicon circuits easily, and such layers are adherent to

759-628: A true insulator like glass). Wet etching of GaAs industrially uses an oxidizing agent such as hydrogen peroxide or bromine water, and the same strategy has been described in a patent relating to processing scrap components containing GaAs where the Ga is complexed with a hydroxamic acid ("HA"), for example: This reaction produces arsenic acid . GaAs can be used for various transistor types: The HBT can be used in integrated injection logic (I L). The earliest GaAs logic gate used Buffered FET Logic (BFL). From c.  1975 to 1995

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828-829: A very high impurity density, which makes it difficult to build integrated circuits with small structures, so the 500 nm process is a common process for GaAs. Silicon has about three times the thermal conductivity of GaAs, with less risk of local overheating in high power devices. Gallium arsenide (GaAs) transistors are used in the RF power amplifiers for cell phones and wireless communicating. GaAs wafers are used in laser diodes , photodetectors , and radio frequency (RF) amplifiers for mobile phones and base stations. GaAs transistors are also integral to monolithic microwave integrated circuits (MMICs) , utilized in satellite communication and radar systems, as well as in low-noise amplifiers (LNAs) that enhance weak signals. Gallium arsenide

897-399: Is a powerful oxidizer . Sulfite ( SO 2− 3 ) is oxidized to sulfate ( SO 2− 4 ). Under alkaline conditions, hydrogen peroxide is a reductant. When H 2 O 2 acts as a reducing agent, oxygen gas is also produced. For example, hydrogen peroxide will reduce sodium hypochlorite and potassium permanganate , which is a convenient method for preparing oxygen in

966-399: Is a result of higher carrier mobilities and lower resistive device parasitics. These superior properties are compelling reasons to use GaAs circuitry in mobile phones , satellite communications, microwave point-to-point links and higher frequency radar systems. It is also used in the manufacture of Gunn diodes for the generation of microwaves . Another advantage of GaAs is that it has

1035-470: Is a useful "carrier" for H 2 O 2 in some reactions. Hydrogen peroxide ( H 2 O 2 ) is a nonplanar molecule with (twisted) C 2 symmetry ; this was first shown by Paul-Antoine Giguère in 1950 using infrared spectroscopy . Although the O−O bond is a single bond , the molecule has a relatively high rotational barrier of 386  cm (4.62  kJ / mol ) for rotation between enantiomers via

1104-510: Is a weak acid, forming hydroperoxide or peroxide salts with many metals. It also converts metal oxides into the corresponding peroxides. For example, upon treatment with hydrogen peroxide, chromic acid ( CrO 3 and H 2 SO 4 ) forms a blue peroxide CrO(O 2 ) 2 . The aerobic oxidation of glucose in the presence of the enzyme glucose oxidase produces hydrogen peroxide. The conversion affords gluconolactone : Superoxide dismutases (SOD)s are enzymes that promote

1173-570: Is abundant and cheap to process in the form of silicate minerals. The economies of scale available to the silicon industry has also hindered the adoption of GaAs. In addition, a Si crystal has a very stable structure and can be grown to very large diameter boules and processed with very good yields. It is also a fairly good thermal conductor, thus enabling very dense packing of transistors that need to get rid of their heat of operation, all very desirable for design and manufacturing of very large ICs . Such good mechanical characteristics also make it

1242-456: Is also fairly high, being comparable to that of hydrazine and water, with only hydroxylamine crystallising significantly more readily, indicative of particularly strong hydrogen bonding. Diphosphane and hydrogen disulfide exhibit only weak hydrogen bonding and have little chemical similarity to hydrogen peroxide. Structurally, the analogues all adopt similar skewed structures, due to repulsion between adjacent lone pairs . Hydrogen peroxide

1311-428: Is also preliminary evidence that spalling could be used to remove the substrate for reuse. An alternative path to reduce substrate cost is to use cheaper materials, although materials for this application are not currently commercially available or developed. Yet another consideration to lower GaAs solar cell costs could be concentrator photovoltaics . Concentrators use lenses or parabolic mirrors to focus light onto

1380-436: Is also used for making diode lasers . InAs is well known for its high electron mobility and narrow energy bandgap. It is widely used as a terahertz radiation source as it is a strong photo-Dember emitter. Quantum dots can be formed in a monolayer of indium arsenide on indium phosphide or gallium arsenide. The mismatches of lattice constants of the materials create tensions in the surface layer, which in turn leads to

1449-505: Is an important semiconductor material for high-cost, high-efficiency solar cells and is used for single-crystalline thin-film solar cells and for multi-junction solar cells . The first known operational use of GaAs solar cells in space was for the Venera 3 mission, launched in 1965. The GaAs solar cells, manufactured by Kvant, were chosen because of their higher performance in high temperature environments. GaAs cells were then used for

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1518-444: Is attributed to the effects of hydrogen bonding , which is absent in the gaseous state. Crystals of H 2 O 2 are tetragonal with the space group D 4 or P 4 1 2 1 2. In aqueous solutions , hydrogen peroxide forms a eutectic mixture, exhibiting freezing-point depression down as low as –56 °C; pure water has a freezing point of 0 °C and pure hydrogen peroxide of –0.43 °C. The boiling point of

1587-402: Is epitaxial lift-off (ELO), but this method is time-consuming, somewhat dangerous (with its use of hydrofluoric acid ), and requires multiple post-processing steps. However, other methods have been proposed that use phosphide-based materials and hydrochloric acid to achieve ELO with surface passivation and minimal post- etching residues and allows for direct reuse of the GaAs substrate. There

1656-688: Is found in biological systems including the human body. Enzymes that use or decompose hydrogen peroxide are classified as peroxidases . The boiling point of H 2 O 2 has been extrapolated as being 150.2 °C (302.4 °F), approximately 50 °C (90 °F) higher than water. In practice, hydrogen peroxide will undergo potentially explosive thermal decomposition if heated to this temperature. It may be safely distilled at lower temperatures under reduced pressure. Hydrogen peroxide forms stable adducts with urea ( hydrogen peroxide–urea ), sodium carbonate ( sodium percarbonate ) and other compounds. An acid-base adduct with triphenylphosphine oxide

1725-406: Is highly resistive. Combined with a high dielectric constant , this property makes GaAs a very good substrate for integrated circuits and unlike Si provides natural isolation between devices and circuits. This has made it an ideal material for monolithic microwave integrated circuits (MMICs), where active and essential passive components can readily be produced on a single slice of GaAs. One of

1794-550: Is largely due to the cost of GaAs solar cells - in space applications, high performance is required and the corresponding high cost of the existing GaAs technologies is accepted. For example, GaAs-based photovoltaics show the best resistance to gamma radiation and high temperature fluctuations, which are of great importance for spacecraft. But in comparison to other solar cells, III-V solar cells are two to three orders of magnitude more expensive than other technologies such as silicon-based solar cells. The primary sources of this cost are

1863-543: Is less than 0.014 μg/m , and in moderate photochemical smog it is 14 to 42 μg/m . The amount of hydrogen peroxide in biological systems can be assayed using a fluorometric assay . Alexander von Humboldt is sometimes said to have been the first to report the first synthetic peroxide, barium peroxide , in 1799 as a by-product of his attempts to decompose air, although this is disputed due to von Humboldt's ambiguous wording. Nineteen years later Louis Jacques Thénard recognized that this compound could be used for

1932-529: Is often used as a substrate material for the epitaxial growth of other III-V semiconductors, including indium gallium arsenide , aluminum gallium arsenide and others. Gallium arsenide was first synthesized and studied by Victor Goldschmidt and his co-partner Donder Vwishuna in 1926 by passing arsenic vapors mixed with hydrogen over gallium(III) oxide at 600 °C. The semiconductor properties of GaAs and other III-V compounds were patented by Heinrich Welker at Siemens-Schuckert in 1951 and described in

2001-432: Is often used in alloys with other semiconductor compounds for these applications. N -type GaAs doped with silicon donor atoms (on Ga sites) and boron acceptor atoms (on As sites) responds to ionizing radiation by emitting scintillation photons. At cryogenic temperatures it is among the brightest scintillators known and is a promising candidate for detecting rare electronic excitations from interacting dark matter, due to

2070-479: Is oxidation of thioethers to form sulfoxides , such as conversion of thioanisole to methyl phenyl sulfoxide : Alkaline hydrogen peroxide is used for epoxidation of electron-deficient alkenes such as acrylic acid derivatives, and for the oxidation of alkylboranes to alcohols , the second step of hydroboration-oxidation . It is also the principal reagent in the Dakin oxidation process. Hydrogen peroxide

2139-527: Is produced by various biological processes mediated by enzymes . Hydrogen peroxide has been detected in surface water, in groundwater, and in the atmosphere . It can also form when water is exposed to UV light. Sea water contains 0.5 to 14 μg/L of hydrogen peroxide, and freshwater contains 1 to 30 μg/L. Concentrations in air are about 0.4 to 4 μg/m , varying over several orders of magnitude depending in conditions such as season, altitude, daylight and water vapor content. In rural nighttime air it

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2208-569: Is still used, was developed during the 1930s by the German chemical manufacturer IG Farben in Ludwigshafen . The increased demand and improvements in the synthesis methods resulted in the rise of the annual production of hydrogen peroxide from 35,000 tonnes in 1950, to over 100,000 tonnes in 1960, to 300,000 tonnes by 1970; by 1998 it reached 2.7 million tonnes. Early attempts failed to produce neat hydrogen peroxide. Anhydrous hydrogen peroxide

2277-414: The trans configuration, and 2460 cm (29.4 kJ/mol) via the cis configuration. These barriers are proposed to be due to repulsion between the lone pairs of the adjacent oxygen atoms and dipolar effects between the two O–H bonds. For comparison, the rotational barrier for ethane is 1040 cm (12.4 kJ/mol). The approximately 100° dihedral angle between the two O–H bonds makes

2346-486: The Fermi level to be pinned to near the center of the band gap, so that this GaAs crystal has very low concentration of electrons and holes. This low carrier concentration is similar to an intrinsic (perfectly undoped) crystal, but much easier to achieve in practice. These crystals are called "semi-insulating", reflecting their high resistivity of 10 –10 Ω·cm (which is quite high for a semiconductor, but still much lower than

2415-493: The Fraunhofer Institute for Solar Energy Systems achieved a 68.9% efficiency when exposing a GaAs thin film photovoltaic cell to monochromatic laser light with a wavelength of 858 nanometers. Today, multi-junction GaAs cells have the highest efficiencies of existing photovoltaic cells and trajectories show that this is likely to continue to be the case for the foreseeable future. In 2022, Rocket Lab unveiled

2484-714: The Lunokhod rovers for the same reason. In 1970, the GaAs heterostructure solar cells were developed by the team led by Zhores Alferov in the USSR , achieving much higher efficiencies. In the early 1980s, the efficiency of the best GaAs solar cells surpassed that of conventional, crystalline silicon -based solar cells. In the 1990s, GaAs solar cells took over from silicon as the cell type most commonly used for photovoltaic arrays for satellite applications. Later, dual- and triple-junction solar cells based on GaAs with germanium and indium gallium phosphide layers were developed as

2553-436: The disproportionation of superoxide into oxygen and hydrogen peroxide. Peroxisomes are organelles found in virtually all eukaryotic cells. They are involved in the catabolism of very long chain fatty acids , branched chain fatty acids , D -amino acids , polyamines , and biosynthesis of plasmalogens and ether phospholipids , which are found in mammalian brains and lungs. They produce hydrogen peroxide in

2622-421: The epitaxial growth costs and the substrate the cell is deposited on. GaAs solar cells are most commonly fabricated utilizing epitaxial growth techniques such as metal-organic chemical vapor deposition (MOCVD) and hydride vapor phase epitaxy (HVPE). A significant reduction in costs for these methods would require improvements in tool costs, throughput, material costs, and manufacturing efficiency. Increasing

2691-517: The 1820s, but early attempts of industrial production of peroxides failed. The first plant producing hydrogen peroxide was built in 1873 in Berlin . The discovery of the synthesis of hydrogen peroxide by electrolysis with sulfuric acid introduced the more efficient electrochemical method. It was first commercialized in 1908 in Weißenstein , Carinthia , Austria. The anthraquinone process , which

2760-470: The Si-SiO 2 . Aluminum oxide (Al 2 O 3 ) has been extensively studied as a possible gate oxide for GaAs (as well as InGaAs ). The third advantage of silicon is that it possesses a higher hole mobility compared to GaAs (500 versus 400 cm V s ). This high mobility allows the fabrication of higher-speed P-channel field-effect transistors , which are required for CMOS logic. Because they lack

2829-495: The absorptivity of GaAs is so high that only a few micrometers of thickness are needed to absorb all of the light. Consequently, GaAs thin films must be supported on a substrate material. Silicon is a pure element, avoiding the problems of stoichiometric imbalance and thermal unmixing of GaAs. Silicon has a nearly perfect lattice; impurity density is very low and allows very small structures to be built (down to 5 nm in commercial production as of 2020 ). In contrast, GaAs has

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2898-427: The anthraquinone. Most commercial processes achieve oxidation by bubbling compressed air through a solution of the anthrahydroquinone, with the hydrogen peroxide then extracted from the solution and the anthraquinone recycled back for successive cycles of hydrogenation and oxidation. The net reaction for the anthraquinone-catalyzed process is: The economics of the process depend heavily on effective recycling of

2967-551: The basis of a triple-junction solar cell, which held a record efficiency of over 32% and can operate also with light as concentrated as 2,000 suns. This kind of solar cell powered the Mars Exploration Rovers Spirit and Opportunity , which explored Mars ' surface. Also many solar cars utilize GaAs in solar arrays, as did the Hubble Telescope. GaAs-based devices hold the world record for

3036-481: The cell is mounted to a secondary handle and the GaAs substrate is removed. A main advantage of the IMM process is that the inverted growth according to lattice mismatch allows a path to higher cell efficiency. Complex designs of Al x Ga 1−x As-GaAs devices using quantum wells can be sensitive to infrared radiation ( QWIP ). GaAs diodes can be used for the detection of X-rays. Despite GaAs-based photovoltaics being

3105-412: The clear champions of efficiency for solar cells, they have relatively limited use in today's market. In both world electricity generation and world electricity generating capacity, solar electricity is growing faster than any other source of fuel (wind, hydro, biomass, and so on) for the last decade. However, GaAs solar cells have not currently been adopted for widespread solar electricity generation. This

3174-443: The concentration increases above 68%) these grades are potentially far more hazardous and require special care in dedicated storage areas. Buyers must typically allow inspection by commercial manufacturers. Hydrogen peroxide has several structural analogues with H m X−XH n bonding arrangements (water also shown for comparison). It has the highest (theoretical) boiling point of this series (X = O, S, N, P). Its melting point

3243-408: The deposition rate could reduce costs, but this cost reduction would be limited by the fixed times in other parts of the process such as cooling and heating. The substrate used to grow these solar cells is usually germanium or gallium arsenide which are notably expensive materials. One of the main pathways to reduce substrate costs is to reuse the substrate. An early method proposed to accomplish this

3312-533: The ever-improving CMOS microprocessor. Cray eventually built one GaAs-based machine in the early 1990s, the Cray-3 , but the effort was not adequately capitalized, and the company filed for bankruptcy in 1995. Complex layered structures of gallium arsenide in combination with aluminium arsenide (AlAs) or the alloy Al x Ga 1−x As can be grown using molecular-beam epitaxy (MBE) or using metalorganic vapor-phase epitaxy (MOVPE). Because GaAs and AlAs have almost

3381-497: The extraction solvents, the hydrogenation catalyst and the expensive quinone . Hydrogen peroxide was once prepared industrially by hydrolysis of ammonium persulfate : [NH 4 ] 2 S 2 O 8 was itself obtained by the electrolysis of a solution of ammonium bisulfate ( [NH 4 ]HSO 4 ) in sulfuric acid . Small amounts are formed by electrolysis, photochemistry , electric arc , and related methods. A commercially viable route for hydrogen peroxide via

3450-694: The first GaAs microprocessors was developed in the early 1980s by the RCA Corporation and was considered for the Star Wars program of the United States Department of Defense . These processors were several times faster and several orders of magnitude more radiation resistant than their silicon counterparts, but were more expensive. Other GaAs processors were implemented by the supercomputer vendors Cray Computer Corporation, Convex , and Alliant in an attempt to stay ahead of

3519-407: The following six essential factors: For this purpose an optical fiber tip of an optical fiber temperature sensor is equipped with a gallium arsenide crystal. Starting at a light wavelength of 850 nm GaAs becomes optically translucent. Since the spectral position of the band gap is temperature dependent, it shifts about 0.4 nm/K. The measurement device contains a light source and a device for

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3588-555: The formation of the quantum dots. Quantum dots can also be formed in indium gallium arsenide, as indium arsenide dots sitting in the gallium arsenide matrix. Gallium arsenide Gallium arsenide ( GaAs ) is a III-V direct band gap semiconductor with a zinc blende crystal structure. Gallium arsenide is used in the manufacture of devices such as microwave frequency integrated circuits , monolithic microwave integrated circuits , infrared light-emitting diodes , laser diodes , solar cells and optical windows. GaAs

3657-458: The highest-efficiency single-junction solar cell at 29.1% (as of 2019). This high efficiency is attributed to the extreme high quality GaAs epitaxial growth, surface passivation by the AlGaAs, and the promotion of photon recycling by the thin film design. GaAs-based photovoltaics are also responsible for the highest efficiency (as of 2022) of conversion of light to electricity, as researchers from

3726-445: The laboratory: The oxygen produced from hydrogen peroxide and sodium hypochlorite is in the singlet state . Hydrogen peroxide also reduces silver oxide to silver : Although usually a reductant, alkaline hydrogen peroxide converts Mn(II) to the dioxide: In a related reaction, potassium permanganate is reduced to Mn by acidic H 2 O 2 : Hydrogen peroxide is frequently used as an oxidizing agent . Illustrative

3795-547: The main logic families used were: Some electronic properties of gallium arsenide are superior to those of silicon . It has a higher saturated electron velocity and higher electron mobility , allowing gallium arsenide transistors to function at frequencies in excess of 250 GHz. GaAs devices are relatively insensitive to overheating, owing to their wider energy band gap, and they also tend to create less noise (disturbance in an electrical signal) in electronic circuits than silicon devices, especially at high frequencies. This

3864-530: The middle of the 20th century at least half a dozen hypothetical isomeric variants of two main options seemed to be consistent with the available evidence. In 1934, the English mathematical physicist William Penney and the Scottish physicist Gordon Sutherland proposed a molecular structure for hydrogen peroxide that was very similar to the presently accepted one. In 1994, world production of H 2 O 2

3933-440: The molecule chiral . It is the smallest and simplest molecule to exhibit enantiomerism . It has been proposed that the enantiospecific interactions of one rather than the other may have led to amplification of one enantiomeric form of ribonucleic acids and therefore an origin of homochirality in an RNA world . The molecular structures of gaseous and crystalline H 2 O 2 are significantly different. This difference

4002-522: The preparation of a previously unknown compound, which he described as eau oxygénée ("oxygenated water") — subsequently known as hydrogen peroxide. An improved version of Thénard's process used hydrochloric acid , followed by addition of sulfuric acid to precipitate the barium sulfate byproduct. This process was used from the end of the 19th century until the middle of the 20th century. The bleaching effect of peroxides and their salts on natural dyes had been known since Thénard's experiments in

4071-551: The production or use of GaAs. Hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula H 2 O 2 . In its pure form, it is a very pale blue liquid that is slightly more viscous than water . It is used as an oxidizer , bleaching agent, and antiseptic , usually as a dilute solution (3%–6% by weight) in water for consumer use and in higher concentrations for industrial use. Concentrated hydrogen peroxide, or " high-test peroxide ", decomposes explosively when heated and has been used as both

4140-447: The reaction of hydrogen with oxygen favours production of water but can be stopped at the peroxide stage. One economic obstacle has been that direct processes give a dilute solution uneconomic for transportation. None of these has yet reached a point where it can be used for industrial-scale synthesis. Hydrogen peroxide is about 1000 times stronger as an acid than water. Hydrogen peroxide disproportionates to form water and oxygen with

4209-401: The reduction of an anthraquinone (such as 2-ethylanthraquinone or the 2-amyl derivative) to the corresponding anthrahydroquinone, typically by hydrogenation on a palladium catalyst . In the presence of oxygen , the anthrahydroquinone then undergoes autoxidation : the labile hydrogen atoms of the hydroxy groups transfer to the oxygen molecule, to give hydrogen peroxide and regenerating

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4278-454: The same lattice constant , the layers have very little induced strain , which allows them to be grown almost arbitrarily thick. This allows extremely high performance and high electron mobility HEMT transistors and other quantum well devices. GaAs is used for monolithic radar power amplifiers (but GaN can be less susceptible to heat damage). Silicon has three major advantages over GaAs for integrated circuit manufacture. First, silicon

4347-467: The same mixtures is also depressed in relation with the mean of both boiling points (125.1 °C). It occurs at 114 °C. This boiling point is 14 °C greater than that of pure water and 36.2 °C less than that of pure hydrogen peroxide. Hydrogen peroxide is most commonly available as a solution in water. For consumers, it is usually available from pharmacies at 3 and 6 wt% concentrations. The concentrations are sometimes described in terms of

4416-452: The semiconductor. The surface can be passivated by depositing a cubic gallium(II) sulfide layer using a tert-butyl gallium sulfide compound such as ( BuGaS) 7 . In the presence of excess arsenic, GaAs boules grow with crystallographic defects ; specifically, arsenic antisite defects (an arsenic atom at a gallium atom site within the crystal lattice). The electronic properties of these defects (interacting with others) cause

4485-527: The spectral detection of the band gap. With the changing of the band gap, (0.4 nm/K) an algorithm calculates the temperature (all 250 ms). GaAs may have applications in spintronics as it can be used instead of platinum in spin-charge converters and may be more tunable. The environment, health and safety aspects of gallium arsenide sources (such as trimethylgallium and arsine ) and industrial hygiene monitoring studies of metalorganic precursors have been reported. California lists gallium arsenide as

4554-416: The underlying silicon. SiO 2 is not only a good insulator (with a band gap of 8.9 eV ), but the Si-SiO 2 interface can be easily engineered to have excellent electrical properties, most importantly low density of interface states. GaAs does not have a native oxide, does not easily support a stable adherent insulating layer, and does not possess the dielectric strength or surface passivating qualities of

4623-420: The volume of oxygen gas generated; one milliliter of a 20-volume solution generates twenty milliliters of oxygen gas when completely decomposed. For laboratory use, 30 wt% solutions are most common. Commercial grades from 70% to 98% are also available, but due to the potential of solutions of more than 68% hydrogen peroxide to be converted entirely to steam and oxygen (with the temperature of the steam increasing as

4692-409: Was around 1.9 million tonnes and grew to 2.2 million in 2006, most of which was at a concentration of 70% or less. In that year, bulk 30% H 2 O 2 sold for around 0.54 USD / kg , equivalent to US$ 1.50/kg (US$ 0.68/ lb ) on a "100% basis". Today, hydrogen peroxide is manufactured almost exclusively by the anthraquinone process , which was originally developed by BASF in 1939. It begins with

4761-473: Was first obtained by vacuum distillation . Determination of the molecular structure of hydrogen peroxide proved to be very difficult. In 1892, the Italian physical chemist Giacomo Carrara (1864–1925) determined its molecular mass by freezing-point depression , which confirmed that its molecular formula is H 2 O 2 . H 2 O=O seemed to be just as possible as the modern structure, and as late as in

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