Indium gallium arsenide
Encyclopedia
Indium gallium arsenide is a semiconductor
composed of indium
, gallium
and arsenic
. It is used in high-power and high-frequency electronics because of its superior electron velocity with respect to the more common semiconductors silicon
and gallium arsenide. InGaAs bandgap also makes it the detector material of choice in optical fiber
communication at 1300 and 1550 nm. Gallium indium arsenide (GaInAs) is an alternative name for InGaAs.
Indium gallium arsenide was synthesized by T.P. Pearsall in 1976, who was the first to realize that single crystal indium gallium arsenide could be grown epitaxially on InP. Pearsall is credited with the determination of the band gap, the effective masses of electrons and holes, electron and hole mobilities and other fundamental properties of indium gallium arsenide. In 1978, Pearsall demonstrated the first high-performance p-i-n detector, and two years later the uni-traveling-carrier (utc) photodiode. Both devices are currently widely used in optical fibre telecommunications.
The indium content determines the two-dimensional charge carrier
density.
of InP and avoid mechanical strain, In0.53Ga0.47As, this composition has a cut-off wavelength of 1.68 μm.
By increasing the ratio of In further compared to Ga it is possible to extend the cut-off wavelength up to about 2.6 µm. In that case special measures have to be taken to avoid mechanical strain from differences in lattice constant
s.
GaAs is lattice mismatched to Ge by 0.08%. With the addition of 1.5% In to the alloy, InGaAs, becomes perfectly latticed matched to Ge. The complete elimination of film stress reduces the defect densities of the epi InGaAs layer compared to straight GaAs.
.
InGaAs is also a popular material in infrared detector
s. It is widely replacing germanium
as a detector material mainly due to lower dark current
(internally generated current). It is used as the detector material in some short-wave infrared cameras. InGaAs also has lower multiplication noise than germanium when used as the active multiplication layer of an avalanche photodiode
.
InGaAs can be used as a laser medium. Devices have been constructed operating at wavelengths of 905 nm, 980 nm, 1060 nm, and 1300 nm. InGaAs quantum dots on GaAs have also been studied as lasers.
In0.015Ga0.985As can be used as an intermediate band-gap junction in multi-junction photovoltaic cells with a perfect lattice match to Ge. The perfect lattice match to Ge reduces defect density, improving cell efficiency.
, trimethylindium
and arsine
) and industrial hygiene monitoring studies of standard MOVPE sources have been reported recently in a review.
Semiconductor
A semiconductor is a material with electrical conductivity due to electron flow intermediate in magnitude between that of a conductor and an insulator. This means a conductivity roughly in the range of 103 to 10−8 siemens per centimeter...
composed of indium
Indium
Indium is a chemical element with the symbol In and atomic number 49. This rare, very soft, malleable and easily fusible post-transition metal is chemically similar to gallium and thallium, and shows the intermediate properties between these two...
, gallium
Gallium
Gallium is a chemical element that has the symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium salt in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. As it liquefies...
and arsenic
Arsenic
Arsenic is a chemical element with the symbol As, atomic number 33 and relative atomic mass 74.92. Arsenic occurs in many minerals, usually in conjunction with sulfur and metals, and also as a pure elemental crystal. It was first documented by Albertus Magnus in 1250.Arsenic is a metalloid...
. It is used in high-power and high-frequency electronics because of its superior electron velocity with respect to the more common semiconductors silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
and gallium arsenide. InGaAs bandgap also makes it the detector material of choice in optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
communication at 1300 and 1550 nm. Gallium indium arsenide (GaInAs) is an alternative name for InGaAs.
Indium gallium arsenide was synthesized by T.P. Pearsall in 1976, who was the first to realize that single crystal indium gallium arsenide could be grown epitaxially on InP. Pearsall is credited with the determination of the band gap, the effective masses of electrons and holes, electron and hole mobilities and other fundamental properties of indium gallium arsenide. In 1978, Pearsall demonstrated the first high-performance p-i-n detector, and two years later the uni-traveling-carrier (utc) photodiode. Both devices are currently widely used in optical fibre telecommunications.
The indium content determines the two-dimensional charge carrier
Charge carrier
In physics, a charge carrier is a free particle carrying an electric charge, especially the particles that carry electric currents in electrical conductors. Examples are electrons and ions...
density.
Properties
The optical and mechanical properties of InGaAs can be varied by changing the ratio of In and Ga, InxGa1-xAs. The InGaAs device is normally grown on an indium phosphide (InP) substrate. In order to match the lattice constantLattice constant
The lattice constant [or lattice parameter] refers to the constant distance between unit cells in a crystal lattice. Lattices in three dimensions generally have three lattice constants, referred to as a, b, and c. However, in the special case of cubic crystal structures, all of the constants are...
of InP and avoid mechanical strain, In0.53Ga0.47As, this composition has a cut-off wavelength of 1.68 μm.
By increasing the ratio of In further compared to Ga it is possible to extend the cut-off wavelength up to about 2.6 µm. In that case special measures have to be taken to avoid mechanical strain from differences in lattice constant
Lattice constant
The lattice constant [or lattice parameter] refers to the constant distance between unit cells in a crystal lattice. Lattices in three dimensions generally have three lattice constants, referred to as a, b, and c. However, in the special case of cubic crystal structures, all of the constants are...
s.
GaAs is lattice mismatched to Ge by 0.08%. With the addition of 1.5% In to the alloy, InGaAs, becomes perfectly latticed matched to Ge. The complete elimination of film stress reduces the defect densities of the epi InGaAs layer compared to straight GaAs.
Applications
HEMT devices using InGaAs channels are one of the fastest types of transistorTransistor
A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...
.
InGaAs is also a popular material in infrared detector
Infrared detector
An infrared detector is a photodetector that reacts to infrared radiation. The two main types of detectors are thermal and photonic.The thermal effects of the incident IR radiation can be followed through many temperature dependent phenomena....
s. It is widely replacing germanium
Germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The isolated element is a semiconductor, with an appearance most similar to elemental silicon....
as a detector material mainly due to lower dark current
Dark current
Dark current is the constant response exhibited by a receptor of radiation during periods when it is not actively being exposed to light. It may refer to:...
(internally generated current). It is used as the detector material in some short-wave infrared cameras. InGaAs also has lower multiplication noise than germanium when used as the active multiplication layer of an avalanche photodiode
Avalanche photodiode
An avalanche photodiode is a highly sensitive semiconductor electronic device that exploits the photoelectric effect to convert light to electricity. APDs can be thought of as photodetectors that provide a built-in first stage of gain through avalanche multiplication. From a functional standpoint,...
.
InGaAs can be used as a laser medium. Devices have been constructed operating at wavelengths of 905 nm, 980 nm, 1060 nm, and 1300 nm. InGaAs quantum dots on GaAs have also been studied as lasers.
In0.015Ga0.985As can be used as an intermediate band-gap junction in multi-junction photovoltaic cells with a perfect lattice match to Ge. The perfect lattice match to Ge reduces defect density, improving cell efficiency.
Safety and toxicity aspects
The toxicology of InGaAs has not been fully investigated. The dust is an irritant to skin, eyes and lungs. The environment, health and safety aspects of indium gallium arsenide sources (such as trimethylgalliumTrimethylgallium
Trimethylgallium, Ga3, often abbreviated to TMG or TMGa, is the preferred metalorganic source of gallium for metalorganic vapour phase epitaxy of gallium-containing compound semiconductors, such as GaAs, GaN, GaP, GaSb, InGaAs, InGaN, AlGaInP, InGaP and AlInGaNP.-Properties:TMG is a clear,...
, trimethylindium
Trimethylindium
Trimethylindium , In3, is the preferred metalorganic source of Indium for metalorganic vapour phase epitaxy of indium-containing compound semiconductors, such as InP, InAs, InN, InSb, GaInAs, InGaN, AlGaInP, AlInP, AlInGaNP etc. TMI is a white, crystalline and sublimable solid, with melting point...
and arsine
Arsine
Arsine is the chemical compound with the formula AsH3. This flammable, pyrophoric, and highly toxic gas is one of the simplest compounds of arsenic...
) and industrial hygiene monitoring studies of standard MOVPE sources have been reported recently in a review.
See also
- indium gallium phosphideIndium gallium phosphideIndium gallium phosphide , also called gallium indium phosphide , is a semiconductor composed of indium, gallium and phosphorus...
- Indium gallium zinc oxide
- gallium arsenide
- indium arsenide
External links
- NSM data archive at the Ioffe Institute, St. Petersburg, Russia