Gallium arsenide
General
Systematic name	Gallium arsenide
Molecular formula	GaAs
Molar mass	144.645 g/mol
Appearance	Gray cubic crystals.
CAS number	[1303-00-0]
SMILES	Ga#As
Properties
Density and phase	5.3176 g/cm³, solid.
Solubility in water	< 0.1 g/100 ml (20°C)
Melting point	1238°C (1511 K)
Boiling point	?°C (? K)
Electronic Properties
Band gap at 300 K	1.424 eV
Electron effective mass	0.067 me
Light hole effective mass	0.082 me
Heavy hole effective mass	0.45 me
Electron mobility at 300 K	9200 cm²/(V·s)
Hole mobility at 300 K	400 cm²/(V·s)
Structure
Molecular shape	Linear
Crystal structure	Zinc Blende
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	Carcinogenic
NFPA 704	Image File history File links Gallium_arsenide. ... IUPAC nomenclature is a system of naming chemical compounds and of describing the science of chemistry in general. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... The simplified molecular input line entry specification or SMILES is a specification for unambiguously describing the structure of chemical molecules using short ASCII strings. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... Solubility refers to the ability for a given substance, the solute, to dissolve in a solvent. ... This article describes water from a scientific and technical perspective. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... This article or section does not adequately cite its references or sources. ... e- redirects here. ... In solid state physics, a particles effective mass is the mass it seems to carry in the semiclassical model of transport in a crystal. ... In solid state physics, a particles effective mass is the mass it seems to carry in the semiclassical model of transport in a crystal. ... In solid state physics, a particles effective mass is the mass it seems to carry in the semiclassical model of transport in a crystal. ... This does not adequately cite its references or sources. ... In physics, electron mobility (or simply, mobility), is used to describe the relation between drift velocity of electrons or holes in a solid material or electrons/ions in a gas, and an applied electric field. ... four sp³ orbitals three sp² orbitals In chemistry, hybridisation or hybridization (see also spelling differences) is the concept of mixing atomic orbitals to form new hybrid orbitals suitable for the qualitative description of atomic bonding properties. ... Enargite crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... The cubic crystal system is a crystal system where the unit cell is in the shape of a cube. ... The Earths magnetic field, which is approximately a dipole. ... The debye (symbol: D) is a non-SI and non-CGS unit of electrical dipole moment. ... An example MSDS in a US format provides guidance for handling a hazardous substance and information on its composition and properties. ... The examples and perspective in this article or section may not represent a worldwide view. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... Image File history File links NFPA_704. ... 1 3 2
Flash point	Non-flammable
R/S statement	R: R23 R25 S: S1 S2 S20 S21 S22 S28 S41 S45
RTECS number	?
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	?
Other cations	?
Related compounds	?
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

This article is about the chemical compound. For the record label, see Gallium Arsenide.

Gallium arsenide (GaAs) is a compound of two elements, Gallium and Arsenic. It is an important semiconductor and is used to make devices such as microwave frequency integrated circuits (ie, MMICs), infrared light-emitting diodes, laser diodes and solar cells. The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture with air. ... Risk and Safety Statements, also known as R/S statements, R/S numbers, R/S phrases, and R/S sentences, is a system of hazard codes and phrases for labeling dangerous chemicals and compounds. ... R-phrases are defined in Annex III of European Union Directive 67/548/EEC: Nature of special risks attributed to dangerous substances and preparations. ... S-phrases are defined in Annex IV of European Union Directive 67/548/EEC: Safety advice concerning dangerous substances and preparations. ... RTECS, also known as Registry of Toxic Effects of Chemical Substances, is a database of toxicity information compiled from the open scientific literature that is available for charge. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the IR region of the EM spectrum. ... Nuclear Magnetic Resonance Spectroscopy most commonly known as NMR Spectroscopy is the name given to the technique which exploits the magnetic properties of nuclei. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or in common speech mass-spec) is an analytical technique used to measure the mass-to-charge ratio of ions. ... “Multivalent” redirects here. ... “Multivalent” redirects here. ... In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals) and 25 degrees Celsius (298. ... This does not adequately cite its references or sources. ... This article is about the chemical compound. ... General Name, Symbol, Number gallium, Ga, 31 Chemical series poor metals Group, Period, Block 13, 4, p Appearance silvery white   Atomic mass 69. ... General Name, Symbol, Number arsenic, As, 33 Chemical series metalloids Group, Period, Block 15, 4, p Appearance metallic gray Atomic mass 74. ... A semiconductor is a solid whose electrical conductivity can be controlled over a wide range, either permanently or dynamically. ... Microwaves are electromagnetic waves with wavelengths longer than those of terahertz (THz) frequencies, but relatively short for radio waves. ... Integrated circuit showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window showing the integrated circuit inside. ... MMICs, or Monolithic Microwave Integrated Circuits, are integrated circuit (IC) devices that operate at microwave frequencies. ... Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... Led is also the past tense of the verb to lead Blue, green and red LEDs. ... A packaged laser diode with penny for scale. ... A solar cell, a form of photovoltaic cell, is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). ...

Applications

GaAs advantages

GaAs has some electronic properties which are superior to silicon's. It has a higher saturated electron velocity and higher electron mobility, allowing it to function at frequencies in excess of 250 GHz. Also, GaAs devices generate less noise than silicon devices when operated at high frequencies. They can also be operated at higher power levels than the equivalent silicon device because they have higher breakdown voltages. These properties recommend GaAs circuitry in mobile phones, satellite communications, microwave point-to-point links, and some radar systems. It is used in the manufacture of Gunn diodes for generation of microwaves. It has been suggested that Silicons ranking be merged into this article or section. ... This does not adequately cite its references or sources. ... In science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information (signal) being received at a detector. ... Breakdown Voltage (Insulator) = The minimum voltage that makes an insulator react as a conductor. ... U.S. military MILSTAR communications satellite A communications satellite (sometimes abbreviated to comsat) is an artificial satellite stationed in space for the purposes of telecommunications. ... This long range Radar antenna, known as ALTAIR, is used to detect and track space objects in conjunction with ABM testing at the Ronald Reagan Test Site on the Kwajalein atoll[1]. Radar is a system that uses radio waves to determine and map the location, direction, and/or speed... A rough approximation of the VI curve for a Gunn diode, showing the negative differential resistance region A Gunn diode, also known as a transferred electron device (TED) is a form of diode used in high-frequency electronics. ...

Another advantage of GaAs is that it has a direct band gap, which means that it can be used to emit light. Silicon has an indirect bandgap and so is very poor at emitting light. (Nonetheless, recent advances may make silicon LEDs and lasers possible). In semiconductor physics, a direct bandgap means that the minimum of the conduction band lies directly above the maximum of the valence band in momentum space. ... In semiconductor physics, an indirect bandgap is a bandgap in which the minimum energy in the conduction band is shifted by a k-vector, which is determined by the materials crystal structure. ... External links LEd Category: TeX ... For other uses, see Laser (disambiguation). ...

Because of its high switching speed, GaAs would seem to be ideal for computer applications, and for some time in the 1980s many thought that the microelectronics market would switch from silicon to GaAs. The first attempted changes were implemented by the supercomputer vendors Cray Computer Corporation, Convex, and Alliant in an attempt to stay ahead of 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. A supercomputer is a computer that leads the world in terms of processing capacity, particularly speed of calculation, at the time of its introduction. ... Cray Computer Corporation was a spinoff of Cray Research intended to develop and market the Cray-3 supercomputer. ... Convex Computer was a company that produced a number of vector minisupercomputers, supercomputers for small-to-medium-sized businesses. ... Alliant Computer Systems was a computer company that designed and manufactured parallel computing systems. ... Static CMOS Inverter Complementary-symmetry/metal-oxide semiconductor (CMOS) (see-moss, IPA:), is a major class of integrated circuits. ... The Cray-3 was intended to be Cray Researchs successor to the Cray-2 supercomputer. ...

Silicon's advantages

Silicon has three major advantages over GaAs. First, silicon is abundant and cheap to process. Silicon's greater physical strength enables larger wafers (maximum of ~300 mm compared to ~150 mm diameter for GaAs). Si is highly abundant in the Earth's crust, in the form of silicate minerals. The economy of scale available to the silicon industry has also reduced the adoption of GaAs. In chemistry, a silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. ...

The second major advantage of Si is the existence of silicon dioxide—one of the best insulators. Silicon dioxide can easily be incorporated onto silicon circuits, and such layers are adherent to the underlying Si. GaAs does not form a stable adherent insulating layer. R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... This article or section is in need of attention from an expert on the subject. ...

The third, and perhaps most important, advantage of silicon is that it possesses a much higher hole mobility. This high mobility allows the fabrication of higher-speed P-channel field effect transistors, which are required for CMOS logic. Because they lack a fast CMOS structure, GaAs logic circuits have much higher power consumption, which has made them unable to compete with silicon logic circuits. For the following two reasons the electron hole was introduced into calculations. ... Large power N-channel field effect transistor The field-effect transistor (FET) is a transistor that relies on an electric field to control the shape and hence the conductivity of a channel in a semiconductor material. ... Static CMOS Inverter Complementary-symmetry/metal-oxide semiconductor (CMOS) (see-moss, IPA:), is a major class of integrated circuits. ...

GaAs heterostructures

Complex layered structures of gallium arsenide in combination with aluminium arsenide (AlAs) or the alloy Al_xGa_1-xAs can be grown using molecular beam epitaxy (MBE) or using metalorganic vapour phase epitaxy (MOVPE). Because GaAs and AlAs have almost the same lattice constant, the layers have very little induced strain, which allows them to be grown almost arbitrarily thick. This page meets Wikipedias criteria for speedy deletion. ... Aluminium gallium arsenide (also Aluminum gallium arsenide) (AlxGa1-xAs) is a semiconductor with very nearly the same lattice constant as GaAs, but a larger bandgap. ... Molecular beam epitaxy, abbreviated MBE, is the deposition of one or more pure materials onto a single crystal wafer, one layer of atoms at a time, under ultra-high vacuum, forming a perfect crystal. ... Metalorganic vapour phase epitaxy (MOVPE) is a chemical vapour deposition method of epitaxial growth of materials, especially semiconductors from the pyrolysis of organic compounds containing the required chemical elements. ... Lattice constant, or a, defines the distance between atoms in crystal lattice. ... Look up strain in Wiktionary, the free dictionary. ...

Another important application of GaAs is for high efficiency solar cells. The combination of GaAs with germanium and indium gallium phosphide is the basis of a triple junction solar cell which holds the record efficiency of over 32% and can operate also with light as concentrated as 2,000 suns. This kind of solar cell powers the robots Spirit and Opportunity, which are exploring Mars' surface. Also many solar cars utilize GaAs in solar arrays. A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ... General Name, Symbol, Number germanium, Ge, 32 Chemical series metalloids Group, Period, Block 14, 4, p Appearance grayish white Atomic mass 72. ... Indium gallium phosphide (InGaP) is a semiconductor composed of indium, gallium and phosphorus. ... The mission patch for Spirit, featuring Marvin the Martian. ... The mission patch for Opportunity, featuring Duck Dodgers (Daffy Duck). ... Adjectives: Martian Atmosphere Surface pressure: 0. ... A solar car is an electric vehicle powered by solar energy obtained from solar panels on the surface of the car. ...

Single crystals of gallium arsenide can be manufactured by the Bridgeman technique, or the Trice_Goyette_Technique, as the Czochralski process is difficult for this material due to its mechanical properties. However, an encapsulated Czochralski method is used to produce ultra-high purity GaAs for semi-insulators. A single crystal is a crystalline solid in which the crystal lattice of the entire sample is continuous and unbroken to the edges of the sample. ... The Bridgeman technique is a method of growing single crystal ingots or boules. ... The Trice-Goyette Technique is a method of growing monocrystal ingots or boules pioneered by Edward Trice in 1993 for specific use in the Cray-3 gallium arsenide-based Supercomputer. ... The Czochralski process is a method of crystal growth used to obtain single crystals of semiconductors (e. ...

Safety

The toxicological properties of gallium arsenide have not been thoroughly investigated. On one hand, due to its arsenic content, it is considered highly toxic and carcinogenic. On the other hand, the crystal is stable enough that ingested pieces may be passed with negligible absorption by the body. When ground into very fine particles, such as in wafer-polishing processes, the high surface area enables more reaction with water, releasing some arsine and/or dissolved arsenic. 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 recently in a review.^[1] Toxic redirects here, but this is also the name of a song by Britney Spears; see Toxic (song) Look up toxic and toxicity in Wiktionary, the free dictionary. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... Trimethylgallium (abbr: TMG), Ga(CH3)3, (CAS #: 1445-79-0) is the preferred metalorganic source of Gallium for Metalorganic vapour phase epitaxy (MOVPE) of gallium-containing compound semiconductors, such as GaAs, GaN, GaP, GaSb, GaInAs, InGaN, AlInGaP, GaInP, AlInGaNP etc. ... Arsine, the simplest compound of arsenic, is AsH3. ... It has been suggested that Organometallic compounds be merged into this article or section. ...

See also

• Electronics
• Field effect transistor
• Heterostructure emitter bipolar transistor
• Integrated circuit
• Semiconductor
• Semiconductor devices
• solar cell

// Electronics is the study of electron mechanics. ... Large power N-channel field effect transistor The field-effect transistor (FET) is a transistor that relies on an electric field to control the shape and hence the conductivity of a channel in a semiconductor material. ... // The Heterojunction emitter bipolar transistor (HEBT), is a somewhat unique arrangement, with respect to emitter blocking, of minority carriers. ... Integrated circuit showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window showing the integrated circuit inside. ... A semiconductor is a solid whose electrical conductivity can be controlled over a wide range, either permanently or dynamically. ... Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium and gallium arsenide. ... A solar cell, made from a monocrystalline silicon wafer A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. ...

Related materials

• Aluminium arsenide
• Indium arsenide
• Gallium antimonide
• Gallium phosphide
• Aluminium gallium arsenide
• Indium gallium arsenide
• Gallium arsenide phosphide
• Gallium nitride
• MOVPE
• Trimethylgallium
• Arsine

This page meets Wikipedias criteria for speedy deletion. ... Indium arsenide, InAs, or indium monoarsenide, is a semiconductor material, a semiconductor composed of indium and arsenic. ... Gallium antimonide (GaSb) is a semiconducting compound of gallium and antimony of the III-V family. ... Gallium phosphide (GaP), a phosphide of gallium, is a compound semiconductor material with indirect band gap of 2. ... Aluminium gallium arsenide (also Aluminum gallium arsenide) (AlxGa1-xAs) is a semiconductor with very nearly the same lattice constant as GaAs, but a larger bandgap. ... Indium gallium arsenide (InGaAs) is a semiconductor composed of indium, gallium and arsenic. ... Gallium arsenide phosphide (GaAsP) is a semiconductor material, an alloy of gallium arsenide and gallium phosphide. ... Gallium nitride (GaN) is a wide bandgap semiconductor material used in optoelectronic, high-power and high-frequency devices. ... Metalorganic vapour phase epitaxy (MOVPE) is a chemical vapour deposition method of epitaxial growth of materials, especially semiconductors from the pyrolysis of organic compounds containing the required chemical elements. ... Trimethylgallium (abbr: TMG), Ga(CH3)3, (CAS #: 1445-79-0) is the preferred metalorganic source of Gallium for Metalorganic vapour phase epitaxy (MOVPE) of gallium-containing compound semiconductors, such as GaAs, GaN, GaP, GaSb, GaInAs, InGaN, AlInGaP, GaInP, AlInGaNP etc. ... Arsine, the simplest compound of arsenic, is AsH3. ...

References

1. ^ Environment, health and safety issues for sources used in MOVPE growth of compound semiconductors; D V Shenai-Khatkhate, R Goyette, R L DiCarlo and G Dripps, Journal of Crystal Growth, vol. 1-4, pp. 816-821 (2004); DOI:doi:10.1016/j.jcrysgro.2004.09.007

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ...

External links

• Case Studies in Environmental Medicine: Arsenic Toxicity
• Extensive site on the physical properties of Gallium arsenide
• Facts and figures on processing Gallium Arsenide
• Links to external chemical sources