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Encyclopedia > Gallium arsenide

This article is about the chemical compound. For the record label, see Gallium Arsenide. A record label is a brand created by companies that specialize in producing, manufacturing, distributing and promoting audio and sometimes video recordings (especially music videos), on various formats including compact discs, LPs, DVD-Audio, SACDs, and cassettes. ... This article is about the chemical compound. ...


Gallium arsenide (GaAs) is a chemical compound composed of 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 and laser diodes. 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 chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... 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 material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... This page is about the radiation; for the appliance, see microwave oven. ... Optical Microscope image of an integrated circuit showing defects in the aluminium layer deposition. ... MMICs, or Monolithic Microwave Integrated Circuits, are integrated circuit (IC) devices that operate at microwave frequencies. ... Image of a small dog taken 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 microwave radiation. ... Red, pure green, and blue LEDs. ... A packaged laser diode with penny for scale. ...

Properties
General
Name gallium arsenide
Chemical Formula GaAs
Appearance Dark gray cubic crystals
CAS number 1303-00-0
Structure
Formula weight 144.64 u
Lattice constant 0.56533 nm
Crystal structure zincblende
Physical
State of matter at STP solid
Melting point at SP 1513 K
Boiling point at SP ?
Specific gravity 5.318
Electronic
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)
Precautions
NFPA 704
Image:nfpa h3.png Image:nfpa f1.png Image:nfpa r2.png
Toxic YES
Carcinogenic
Decomposition products Highly toxic arsenic fumes
SI units were used where possible.

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 have made GaAs circuitry common in mobile phones, satellite communications, microwave point-to-point links, and some radar systems. 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. ... Color is an important part of the visual arts. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences and alloys. ... ... The atomic mass unit (amu), unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. ... Lattice constant, or a, defines the distance between atoms in crystal lattice. ... Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... Sphalerite sample Another sphalerite sample Sphalerite (ZnS) is a mineral that is the chief ore of zinc. ... 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. ... Temperature and air pressure can vary from one place to another on the Earth, and can also vary in the same place with time. ... In jewelry, a solid gold piece is the alternative to gold-filled or gold-plated jewelry. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... Temperature and air pressure can vary from one place to another on the Earth, and can also vary in the same place with time. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... It has been suggested that Saturation temperature be merged into this article or section. ... Relative density (also known as specific gravity) is a measure of the density of a material. ... In solid state physics and related applied fields, the band gap is the energy difference between the top of the valence band and the bottom of the conduction band in insulators and semiconductors. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... Properties The electron is a fundamental subatomic particle which carries a negative electric charge. ... 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. ... 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. ... 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. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ... General Name, Symbol, Number arsenic, As, 33 Chemical series metalloids Group, Period, Block 15, 4, p Appearance metallic gray Atomic mass 74. ... The International System of Units (abbreviated SI from the French language name Système International dUnités) is the modern form of the metric system. ... General Name, Symbol, Number silicon, Si, 14 Chemical series metalloids Group, Period, Block 14, 3, p Appearance dark gray, bluish tinge Atomic mass 28. ... 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. ... 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 (approximately 40m (130ft) in diameter) rotates on a track to observe activities near the horizon. ...


Another advantage of GaAs is that it has a direct bandgap. This 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 conduction band lies directly above the valence band, in momentum space (see E-k plots). ... 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 ... The range of sizes in which lasers exist is immense, extending from microscopic diode lasers (top) to football field sized neodymium glass lasers (bottom) used for inertial confinement fusion. ...


Its high switching speed makes GaAs seemingly ideal for computer uses, and for some time in the 1980s many thought that it was only a matter of time before the entire market switched off of silicon. The first to attempt this were the supercomputer vendors, with Cray, Convex and Alliant all running GaAs projects in order to stay ahead of the ever-improving CMOS microprocessor. The closest to production was the Cray-3, built to one example in the early 1990s, but the effort was so costly the venture failed 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-2 supercomputer Cray Inc. ... 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 CMOS (pronounced see-moss), which stands for complementary metal-oxide-semiconductor, is a major class of integrated circuits. ... The Cray-3 was intended to be Cray Researchs successor to the Cray-2 supercomputer. ... 1995 (MCMXCV) was a common year starting on Sunday of the Gregorian calendar. ...


Silicon has three major advantages over GaAs. First, silicon is cheap. This is for several reasons: silicon's large wafer size (maximum of ~300 mm compared to ~150 mm diameter), higher strength allowing for easier processing, and of course the scale of the economy.


The second major advantage is the existence of silicon dioxide—one of the best known insulators of any kind. Silicon dioxide can easily be incorporated into silicon circuits wherever a good insulator is required. GaAs circuits must either use the intrinsic semiconductor itself or silicon nitride; neither comes close to the extremely good properties of silicon dioxide. 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. ... // Definition An Insulator is a material or object which resists the flow of electric charge. ... Silicon nitride (Si3N4) is hard, solid substance, that can be obtained by direct reaction between silicon and nitrogen in high temperatures. ...


The third, and perhaps most important, advantage is that silicon posesses a much higher hole mobility. This allows the fabrication of higher-speed P-channel field effect transistors, which are required for CMOS logic. A lack of a fast CMOS structure means that GaAs logic circuits have much higher power consumption, which has made them unable to compete with silicon logic circuits. In solid state physics, an electron hole (usually referred to simply as a hole) is the absence of an electron from the otherwise full valence band. ... Large power N-channed 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 CMOS (pronounced see-moss), which stands for complementary metal-oxide-semiconductor, is a major class of integrated circuits. ...


Complex layered structures of gallium arsenide in combination with aluminium arsenide (AlAs) or the alloy AlxGa1-xAs can be grown using molecular beam epitaxy (MBE). 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. ... Lattice constant, or a, defines the distance between atoms in crystal lattice. ... Look up strain in Wiktionary, the free dictionary. ...


Another important application of Gallium Arsenide is for the realisation of high efficiency solar cell. By combining gallium arsenide with germanium and indium gallium phosphide, it is possible to realise a triple junction solar cell which holds the record efficiency of over 32% and can operate also with concentrated light up to 2.000 suns. This kind of solar cell was used to power the robots Spirit and Opportunity, which are exploring Mars surface. Also many solar cars utilize GaAs in solar arrays. A solar cell, or photovoltaic cell, is a semiconductor device consisting of a large-area p-n junction diode, which in the presence of sunlight is capable of generating usable 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. ... This article needs to be updated. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... For the Roman god, see Mars (god). ... Nuna team at a racecourse Nuna solar powered car, which has travelled up to 140km/h (84mph) A solar car is an electric vehicle powered by solar energy obtained from solar panels on the car. ...


Single crystals of gallium arsenide are manufactured by the Bridgeman technique, as the Czochralski process is difficult for this material. 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 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. However, it is considered highly toxic and carcinogenic. For a list of biologically injurious substances, including toxins and other materials, as well as their effects, see poison. ... In pathology, a carcinogen is any substance or agent that promotes cancer. ...


See also

Two digital voltmeters The field of electronics is the study and use of systems that operate by controlling the flow of electrons or other electrically charged particles in devices such as thermionic valves and semiconductors. ... Large power N-channed 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. ... Optical Microscope image of an integrated circuit showing defects in the aluminium layer deposition. ... A semiconductor is a material with an electrical conductivity that is intermediate between that of an insulator and a conductor. ... Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium and gallium arsenide. ...

External links


  Results from FactBites:
 
DHHS (NIOSH) Publication No. 88-100 (2265 words)
In the second phase of this study, a single dose of gallium arsenide partially dissociated when administered either intratracheally or orally to rats, releasing arsenic that was subsequently distributed, depending on the route of administration, to the lungs, blood, urine, and/or feces.
Gallium was found only in the lungs and feces, suggesting that some of the dissociated gallium was retained in the lung and that a portion was cleared by the mucociliary clearance mechanism and may have been subsequently swallowed.
Metabolism and excretion of orally and intraperitoneally administered gallium arsenide in the hamster.
Method for the manufacture of gallium arsenide thin film solar cells - Patent 4657603 (1898 words)
The present invention relates to a method for the manufacture of gallium arsenide thin film solar cells and in particular to a method wherein a germanium layer is applied to the substrate before the gallium arsenide layers are applied.
Deposition of a gallium arsenide layer 4 on the amorphous regions of the germanium-phosphorous layer 2 cannot occur due to the lack of lattice matching between the two layers.
The gallium aluminum arsenide layer 6, having a layer thickness of 0.5-l um, is p-type conductive and serves as a window layer.
  More results at FactBites »

 
 

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