Hubbry Logo
Gallium arsenideGallium arsenideMain
Open search
Gallium arsenide
Community hub
Gallium arsenide
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Gallium arsenide
Gallium arsenide
Gallium arsenide
View on Wikipedia
from Wikipedia
Gallium arsenide
Samples of gallium arsenide
Samples of gallium arsenide
GaAs wafer of (100) orientation
Names
Preferred IUPAC name
Gallium arsenide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.741 Edit this at Wikidata
EC Number
  • 215-114-8
MeSH gallium+arsenide
RTECS number
  • LW8800000
UNII
UN number 1557
  • InChI=1S/AsH3.Ga.3H/h1H3;;;; ☒N
    Key: SHVQQKYXGUBHBI-UHFFFAOYSA-N ☒N
  • [Ga]#[As]
  • [Ga+3].[As-3]
Properties
GaAs
Molar mass 144.645 g/mol[1]
Appearance Gray crystals[1]
Odor garlic-like when moistened
Density 5.3176 g/cm3[1]
Melting point 1,238 °C (2,260 °F; 1,511 K)[1]
insoluble
Solubility soluble in HCl
insoluble in ethanol, methanol, acetone
Band gap 1.424 eV (at 300 K)[2]
Electron mobility 9000 cm2/(V·s) (at 300 K)[3]
−16.2×10−6 cgs[4]
Thermal conductivity 0.56 W/(cm·K) (at 300 K)[5]
3.3[4]
Structure[5]
Zinc blende
T2d-F-43m
a = 565.315 pm
Tetrahedral
Linear
Hazards
GHS labelling:
GHS08: Health hazard
Danger
H350, H360F, H372
P261, P273, P301+P310, P311, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
3
0
0
Safety data sheet (SDS) External MSDS
Related compounds
Other anions
 Gallium nitride
Gallium phosphide
Gallium antimonide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

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.[6]

GaAs 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.

History

[edit]

Gallium arsenide was first synthesized and studied by Victor Goldschmidt in 1926 by passing arsenic vapors mixed with hydrogen over gallium(III) oxide at 600 °C.[7][8] The semiconductor properties of GaAs and other III-V compounds were patented by Heinrich Welker at Siemens-Schuckert in 1951[9] and described in a 1952 publication.[10] Commercial production of its monocrystals commenced in 1954,[11] and more studies followed in the 1950s.[12] First infrared LEDs were made in 1962.[11]

Preparation and chemistry

[edit]

In the compound, gallium has a +3 oxidation state. Gallium arsenide single crystals can be prepared by three industrial processes:[6]

  • The vertical gradient freeze (VGF) process.[13]
  • Crystal growth using a horizontal zone furnace in the Bridgman-Stockbarger technique, in which gallium and arsenic vapors react, and free molecules deposit on a seed crystal at the cooler end of the furnace.
  • Liquid encapsulated Czochralski (LEC) growth is used for producing high-purity single crystals that can exhibit semi-insulating characteristics (see below). Most GaAs wafers are produced using this process.

Alternative methods for producing films of GaAs include:[6][14]

Oxidation of GaAs occurs in air, degrading performance of the semiconductor. The surface can be passivated by depositing a cubic gallium(II) sulfide layer using a tert-butyl gallium sulfide compound such as (t
BuGaS)
7.[15]

Semi-insulating crystals

[edit]

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 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 107–109 Ω·cm (which is quite high for a semiconductor, but still much lower than a true insulator like glass).[16]

Etching

[edit]

Wet etching of GaAs industrially uses an oxidizing agent such as hydrogen peroxide or bromine water,[17] and the same strategy has been described in a patent relating to processing scrap components containing GaAs where the Ga3+
 is complexed with a hydroxamic acid ("HA"), for example:[18]

GaAs + H
2O
2 + "HA" → "GaA" complex + H
3AsO
4 + 4 H
2O

This reaction produces arsenic acid.[19]

Electronics

[edit]

GaAs digital logic

[edit]

GaAs can be used for various transistor types:[20]

The HBT can be used in integrated injection logic (I2L).

The earliest GaAs logic gate used Buffered FET Logic (BFL).[20]

From c. 1975 to 1995 the main logic families used were:[20]

  • Source-coupled FET logic (SCFL) fastest and most complex, (used by TriQuint & Vitesse)
  • Capacitor–diode FET logic (CDFL) (used by Cray for Cray-3)
  • Direct-coupled FET logic (DCFL) simplest and lowest power (used by Vitesse for VLSI gate arrays)

Comparison with silicon for electronics

[edit]

GaAs advantages

[edit]

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.[22] 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 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.[citation needed]

Another advantage of GaAs is that it has 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.[citation needed]

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.[22]

Because of its wide band gap, pure GaAs 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 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.[23] Other GaAs processors 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.

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) or using metalorganic vapor-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 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).[24]

Silicon advantages

[edit]

Silicon has three major advantages over GaAs for integrated circuit manufacture. First, silicon 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.[citation needed]

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 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.[25]

The second major advantage of Si is the existence of a native oxide (silicon dioxide, SiO2), which is used as an insulator. Silicon dioxide can be incorporated onto silicon circuits easily, and such layers are adherent to the underlying silicon. SiO2 is not only a good insulator (with a band gap of 8.9 eV), but the Si-SiO2 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 the Si-SiO2.[25]

Aluminum oxide (Al2O3) 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 cm2V−1s−1).[26] 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 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, 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.[27]

Silicon is a pure element, avoiding the problems of stoichiometric imbalance and thermal unmixing of GaAs.[28]

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[29]). In contrast, GaAs has a very high impurity density,[30] which makes it difficult to build integrated circuits with small structures, so the 500 nm process is a common process for GaAs.[citation needed]

Silicon has about three times the thermal conductivity of GaAs, with less risk of local overheating in high power devices.[24]

Other applications

[edit]
Triple-junction GaAs cells covering MidSTAR-1

Transistor uses

[edit]

Gallium arsenide (GaAs) transistors are used in the RF power amplifiers for cell phones and wireless communicating.[31] GaAs wafers are used in laser diodes, photodetectors, and radio frequency (RF) amplifiers for mobile phones and base stations.[32] 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.[33][34]

Solar cells and detectors

[edit]

Gallium arsenide 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.[35]

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.[36] GaAs cells were then used for the Lunokhod rovers for the same reason.[citation needed]

In 1970, the GaAs heterostructure solar cells were developed by the team led by Zhores Alferov in the USSR,[37][38][39] 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 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.[40]

GaAs-based devices hold the world record for 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,[41] and the promotion of photon recycling by the thin film design.[42] GaAs-based photovoltaics are also responsible for the highest efficiency (as of 2022) of conversion of light to electricity, as researchers from 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.[43]

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.[44] In 2022, Rocket Lab unveiled a solar cell with 33.3% efficiency[45] 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.[46] After growth, 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 AlxGa1−xAs-GaAs devices using quantum wells can be sensitive to infrared radiation (QWIP).

GaAs diodes can be used for the detection of X-rays.[47]

Future outlook of GaAs solar cells

[edit]

Despite GaAs-based photovoltaics being 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.[48] However, GaAs solar cells have not currently been adopted for widespread solar electricity generation. This 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.[49] 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.[50] The primary sources of this cost are 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.[50] Increasing 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.[50]

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 is epitaxial lift-off (ELO),[51] 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.[52] There is also preliminary evidence that spalling could be used to remove the substrate for reuse.[53] An alternative path to reduce substrate cost is to use cheaper materials, although materials for this application are not currently commercially available or developed.[50]

Yet another consideration to lower GaAs solar cell costs could be concentrator photovoltaics. Concentrators use lenses or parabolic mirrors to focus light onto a solar cell, and thus a smaller (and therefore less expensive) GaAs solar cell is needed to achieve the same results.[54] Concentrator systems have the highest efficiency of existing photovoltaics.[55]

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.

Light-emission devices

[edit]
Band structure of GaAs. The direct gap of GaAs results in efficient emission of infrared light at 1.424 eV (~870 nm).

GaAs has been used to produce near-infrared laser diodes since 1962.[56] It 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[57][58][59] and is a promising candidate for detecting rare electronic excitations from interacting dark matter,[60] due to the following six essential factors:

  1. Silicon donor electrons in GaAs have a binding energy that is among the lowest of all known n-type semiconductors. Free electrons above 8×1015 per cm3 are not "frozen out" and remain delocalized at cryogenic temperatures.[61]
  2. Boron and gallium are group III elements, so boron as an impurity primarily occupies the gallium site. However, a sufficient number occupy the arsenic site and act as acceptors that efficiently trap ionization event holes from the valence band.[62]
  3. After trapping an ionization event hole from the valence band, the boron acceptors can combine radiatively with delocalized donor electrons to produce photons 0.2 eV below the cryogenic band-gap energy (1.52 eV). This is an efficient radiative process that produces scintillation photons that are not absorbed by the GaAs crystal.[58][59]
  4. There is no afterglow, because metastable radiative centers are quickly annihilated by the delocalized electrons. This is evidenced by the lack of thermally induced luminescence.[57]
  5. N-type GaAs has a high refractive index (~3.5) and the narrow-beam absorption coefficient is proportional to the free electron density and typically several per cm.[63][64][65] One would expect that almost all of the scintillation photons should be trapped and absorbed in the crystal, but this is not the case. Recent Monte Carlo and Feynman path integral calculations have shown that the high luminosity could be explained if most of the narrow beam absorption is not absolute absorption but a novel type of optical scattering from the conduction electrons with a cross section of about 5 x 10−18 cm2 that allows scintillation photons to escape total internal reflection.[66][67] This cross section is about 107 times larger than Thomson scattering but comparable to the optical cross section of the conduction electrons in a metal mirror.[68]
  6. N-type GaAs(Si,B) is commercially grown as 10 kg crystal ingots and sliced into thin wafers as substrates for electronic circuits. Boron oxide is used as an encapsulant to prevent the loss of arsenic during crystal growth, but also has the benefit of providing boron acceptors for scintillation.

Fiber optic temperature measurement

[edit]

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 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).[69]

Spin-charge converters

[edit]

GaAs may have applications in spintronics as it can be used instead of platinum in spin-charge converters and may be more tunable.[70]

Traveling-Wave Amplfiers

[edit]

GaAs has been effectively utilized to fabricate traveling-wave amplifiers.[71][72]

Safety

[edit]

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.[73] California lists gallium arsenide as a carcinogen,[74] as do IARC and ECA,[75] and it is considered a known carcinogen in animals.[76][77] 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 the production or use of GaAs.[75]

See also

[edit]

References

[edit]

Cited sources

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Gallium arsenide

View on Grokipedia
from Grokipedia
Gallium arsenide (GaAs) is a binary III-V compound composed of the elements and , forming a direct-bandgap with a blende crystal structure. It exhibits a bandgap energy of 1.42 eV at , high of approximately 8500 cm²/V·s, and a of 5.32 g/cm³, making it suitable for high-performance electronic and optoelectronic devices. Unlike , GaAs's direct bandgap enables efficient light emission and absorption, positioning it as a key in modern technology. GaAs is produced synthetically through bulk crystal growth methods such as the horizontal Bridgman technique or liquid-encapsulated Czochralski (LEC) process to achieve high purity levels, often exceeding 99.9999% (6N) for electronic applications. Its thermal properties include a of 1238°C and thermal conductivity of 0.55 W/cm·°C, which support its use in demanding environments. The material's is 5.65 Å, and it demonstrates superior drift velocity peaking at 2.1 × 10⁷ cm/s compared to , enabling faster switching speeds in transistors. In applications, GaAs is pivotal in , powering light-emitting diodes (LEDs), diodes, and photodetectors due to its efficient radiative recombination. It excels in high-frequency devices such as microwave integrated circuits, radar systems, and cellular base stations, where its low noise and high gain are critical. Additionally, GaAs-based multijunction solar cells have achieved efficiencies up to 47.1% under concentration (as of July 2025), making them essential for space applications and concentrated .

Physical Properties

Crystal Structure and Lattice Parameters

Gallium arsenide (GaAs) adopts the zincblende crystal structure, a cubic variant of the structure characterized by gallium and arsenic atoms arranged in a face-centered cubic lattice, with each atom tetrahedrally coordinated to four of the opposite type. This arrangement corresponds to the F-43m (No. 216). The of GaAs is 5.653 at , reflecting the average Ga-As of approximately 2.45 . The material exhibits a linear coefficient of 5.73×10−65.73 \times 10^{-6} K−1^{-1}, which influences its dimensional stability in thermal processing. GaAs has a density of 5.32 g/cm³ and a of 1238 °C under standard conditions. The zincblende structure underpins the direct bandgap nature of GaAs, with a value of 1.42 eV at 300 K. In single-crystal form, GaAs wafers typically exhibit densities ranging from 10410^4 to 10610^6 cm−2^{-2}, primarily threading dislocations introduced during growth processes like the liquid-encapsulated . Polycrystalline GaAs, by contrast, features significantly higher defect densities due to grain boundaries that serve as nucleation sites for additional and other extended defects, often exceeding those in single crystals by orders of magnitude.

Electronic and Optical Properties

Gallium arsenide (GaAs) is a direct bandgap with a bandgap of 1.42 eV at 300 , which facilitates efficient radiative recombination of electrons and holes, making it suitable for optoelectronic applications. This direct bandgap arises from the zincblende crystal structure, where the conduction band minimum and valence band maximum align at the Γ point in the . The temperature dependence of the bandgap is described by the empirical relation Eg(T)=1.519−5.405×10−4T2T+204 eV,E_g(T) = 1.519 - \frac{5.405 \times 10^{-4} T^2}{T + 204} \ \text{eV}, valid for temperatures between 0 K and 103 K, reflecting the thermal expansion and electron-phonon interactions that narrow the gap with increasing temperature. The electronic transport properties of GaAs are characterized by high electron mobility of 8500 cm²/V·s and hole mobility of 400 cm²/V·s in undoped material at 300 K, enabling low-resistance conduction compared to silicon. These mobilities are influenced by the effective masses of charge carriers, with the electron effective mass me∗=0.067m0m_e^* = 0.067 m_0 (where m0m_0 is the free electron mass) being significantly lighter than the hole effective mass mh∗=0.51m0m_h^* = 0.51 m_0, which reduces scattering and enhances electron transport. The intrinsic carrier concentration at 300 K is approximately ni≈2×106n_i \approx 2 \times 10^6 cm⁻³, indicating low thermal generation of carriers due to the relatively wide bandgap. Additionally, GaAs exhibits a high breakdown electric field of approximately 4×1054 \times 10^5 V/cm, allowing it to sustain larger voltages before avalanche breakdown occurs. Optically, GaAs has a static dielectric constant of 12.9 and a of 3.37 at 1 eV photon energy, contributing to strong light-matter interactions in the near-infrared region. Near the bandgap of 870 nm, the absorption rises sharply to on the order of 10410^4 cm⁻¹, marking the onset of interband transitions and enabling efficient absorption for wavelengths shorter than this cutoff.

Chemical Properties

Reactivity and Stability

Gallium arsenide (GaAs) demonstrates high chemical stability in air at ambient temperatures and up to approximately 200 °C, remaining largely unreactive under these conditions due to the formation of a thin native oxide layer that passivates the surface. However, when heated above 300 °C in the presence of oxygen, GaAs undergoes thermal oxidation, producing gallium(III) oxide (Ga₂O₃) and arsenic(III) oxide (As₂O₃) as primary products. The overall reaction can be represented as 2GaAs + 3O₂ → Ga₂O₃ + As₂O₃, with the process accelerating at higher temperatures and leading to the formation of an amorphous oxide layer below 400 °C. This oxidation behavior is influenced by the preferential reaction at arsenic sites initially, followed by gallium incorporation into the oxide structure. In acidic environments, GaAs exhibits solubility in certain mineral acids but shows resistance to others. It readily dissolves in concentrated (HCl), undergoing the reaction GaAs + 3HCl → GaCl₃ + AsH₃, where gallium trichloride and gas are formed, even at with cold concentrated solutions. In contrast, GaAs is highly resistant to (HF), with negligible etching rates in HF alone, making it suitable for selective processing where oxide removal is desired without substrate attack. For alkaline conditions, GaAs can be etched using solutions of (NaOH) or (KOH), which facilitate anisotropic dissolution, particularly useful in revealing crystallographic features. Under vacuum or inert atmospheres, GaAs remains stable at moderate temperatures but undergoes above 600 °C, dissociating congruently via the reaction 2GaAs → 2Ga + As₂, where sublimes primarily as As₂ vapor due to its higher volatility compared to . This leaves a -enriched surface, with rates increasing significantly at temperatures exceeding 900 °C under low pressure. GaAs also shows excellent stability in aqueous solutions, being insoluble in and neutral media, which supports its use in device fabrication without degradation during wet processing steps. Furthermore, it exhibits strong compatibility with common metallization layers such as Au-Ge-Ni, which form stable ohmic contacts upon annealing, maintaining low resistance and minimal interdiffusion even after prolonged exposure to elevated temperatures up to 400 °C.

Doping and Impurities

Doping in gallium arsenide (GaAs) involves the intentional introduction of impurities to modify its electrical properties, enabling the fabrication of devices such as transistors and diodes by controlling carrier type and concentration. N-type doping introduces donor impurities that provide extra s, typically using (Si), (Te), or (Se), which occupy gallium sites and create shallow donor levels approximately 5-30 meV below the conduction band edge. These dopants achieve electron concentrations in the range of 10^{16} to 10^{18} cm^{-3}, suitable for most electronic applications, with Si being particularly common due to its compatibility with epitaxial growth processes. P-type doping, conversely, incorporates acceptor impurities to generate holes, commonly zinc (Zn), (Be), or (C), which substitute on arsenic sites and form shallow acceptor levels about 20-40 meV above the valence band edge. For instance, the Zn acceptor level is at approximately 31 meV above the valence band, while Be and C levels are around 25-30 meV. Notably, Si exhibits amphoteric behavior in GaAs, acting primarily as a donor but potentially as an acceptor under certain growth conditions, which can complicate precise control during fabrication. Deep-level impurities play a critical role in semi-insulating GaAs, where the EL2 defect—an antisite (As_{Ga})—acts as a mid-gap trap with its (0/+) level at approximately E_c - 0.75 eV, concentrations reaching up to 10^{18} cm^{-3}. This defect compensates shallow donors and acceptors, rendering the material highly resistive for applications like substrates in integrated circuits. In high-purity GaAs, compensation doping balances unintentional shallow impurities, resulting in pinning near 0.7 eV above the valence band due to native deep levels like EL2. Purification techniques minimize these unintentional impurities to enhance compensation control.

History

Discovery and Early Development

Gallium arsenide (GaAs) was first synthesized in 1926 by Victor Moritz Goldschmidt, who prepared the compound by passing a mixture of hydrogen and arsenic vapor over gallium(III) oxide at 600°C, yielding impure polycrystalline material primarily for chemical characterization rather than electronic applications. This early synthesis highlighted GaAs as a III-V intermetallic compound but did not recognize its semiconducting potential, as the material's impurities limited detailed property studies at the time. The semiconducting nature of GaAs was not confirmed until the early 1950s, when Heinrich Welker at Research Laboratories investigated III-V compounds for their electrical properties. In 1952, Welker reported strong in GaAs upon exposure to light, demonstrating its direct bandgap of approximately 1.4 eV and superior compared to , which established GaAs as a promising material. By the mid-1950s, advancements in enabled the production of higher-purity single crystals; in 1956, researchers at RCA Laboratories achieved purer GaAs crystals using zone-refining techniques, reducing impurity levels and allowing more accurate measurements of its electronic characteristics. The 1960s marked foundational device developments with GaAs, building on these material improvements. In 1962, Marshall I. Nathan and colleagues at IBM Watson Research Center fabricated the first GaAs p-n junction , observing from forward-biased junctions at low temperatures, which confirmed the material's suitability for optoelectronic applications. Concurrently, p-n junction diodes were demonstrated in GaAs, enabling early rectifiers and light-emitting devices that exploited its direct bandgap for efficient radiative recombination. These breakthroughs, driven by improved synthesis and doping methods, laid the groundwork for GaAs's role in high-speed electronics.

Commercialization and Key Milestones

The commercialization of gallium arsenide (GaAs) gained momentum in the 1970s, driven by its potential in high-frequency applications. Laboratories introduced the world's first commercial microwave-band large-output GaAs metal-semiconductor (MESFET) in the mid-1970s, enabling advancements in amplification and systems. This development marked the transition from research prototypes to industrial production, with low-noise and power GaAs MESFETs becoming commercially available by the mid-1970s for RF and microwave devices. During the and , GaAs adoption expanded significantly in and integrated circuits, fueled by demand for faster electronics in and . The GaAs IC market reached $106 million by 1985, reflecting early commercial viability for monolithic microwave integrated circuits (MMICs) used in and defense applications. Growth in optoelectronic devices, such as laser diodes and photodetectors, further propelled the sector, though supply chain vulnerabilities emerged due to reliance on high-purity , with periodic price fluctuations affecting production costs in the late 1990s. The and saw a boom in GaAs usage tied to mobile communications, particularly in power amplifiers for and networks, where its high supported efficient RF performance in handsets and base stations. This period solidified GaAs as a key material in the wireless industry, with production scaling to meet surging demand. Geopolitical tensions intensified supply risks when imposed export controls on and in July 2023, directly impacting global GaAs wafer availability since dominates refined output. In 2025, these controls expanded to include additional items related to , such as , which had previously exacerbated shortages for advanced and RF applications. However, on November 10, 2025, suspended the export bans on , , and to the for one year, potentially easing immediate supply pressures as of November 19, 2025. U.S. Geological Survey data indicate that GaAs wafer imports to the were valued at approximately $110 million in 2023, underscoring ongoing dependence on international supply chains amid these restrictions. Global GaAs production in was estimated in the low hundreds of tons annually, largely driven by radio-frequency components for infrastructure and consumer devices, highlighting its enduring market relevance. Recent initiatives, such as the 2023 multi-project wafer (MPW) projects launched by the University of Southern California's MOSIS Service and WIN Semiconductors, have facilitated accessible prototyping for GaAs processes, lowering barriers for innovation in RF and optoelectronic designs.

Synthesis and Production

Crystal Growth Techniques

Gallium arsenide (GaAs) crystals are primarily grown using melt-based techniques for bulk production, with epitaxial methods employed for thin-film layers essential in device fabrication. These processes must address the compound's high of approximately 1238°C and the significant volatility of , which requires pressurized environments to maintain melt stability. Key methods include the Liquid Encapsulated Czochralski (LEC) technique for large-diameter ingots, approaches like Horizontal Bridgman (HB) and Vertical Gradient Freeze (VGF) for lower-defect crystals, and (MBE) for precise thin-film deposition. The LEC method involves synthesizing the GaAs melt in a crucible under an argon overpressure of about 2 MPa to suppress arsenic evaporation, followed by encapsulation with a layer of molten boron oxide (B₂O₃) to prevent melt oxidation and wetting of the crucible walls. A seed crystal is dipped into the melt and slowly pulled upward at rates of 1-5 mm/hr while rotating, forming a single-crystal ingot with diameters typically ranging from 100 to 200 mm. This technique yields crystals with dislocation densities around 10⁴ cm⁻², primarily due to thermoelastic stresses from high thermal gradients of 100-150 K/cm during cooling. LEC remains the dominant industrial process, accounting for over 90% of semi-insulating GaAs substrates, owing to its scalability for masses up to 28 kg per run. In contrast, HB and methods utilize in sealed to achieve seeded growth without encapsulation, enabling better control over the melt by adjusting the (around 0.1 MPa). The HB process involves horizontally translating a horizontal furnace relative to a stationary containing the GaAs charge and seed, resulting in crystals with densities of approximately 10³ cm⁻² but limited to smaller diameters of about 75 mm due to challenges in achieving uniform circular cross-sections. , a vertical variant, employs a stationary in a controlled axial temperature gradient, often with low gradients to minimize stresses, producing ingots up to 150 mm in diameter and densities of 500-5000 cm⁻²—significantly lower than LEC—while using pyrolytic (PBN) or crucibles for reduced contamination. These techniques are favored for optoelectronic applications requiring higher crystalline perfection, though they offer less scalability than LEC. For thin-film applications, MBE enables the growth of high-quality GaAs layers through of elemental and arsenic beams onto a heated substrate, typically at temperatures of 500-600°C to promote adatom mobility and epitaxial alignment. The process occurs in a molecular flow regime, allowing precise control over layer thicknesses from 1 to 100 nm, ideal for heterostructures in . Growth rates are low, on the order of 0.1-1 nm/s, ensuring atomic-level uniformity without involvement. A major challenge across these techniques is maintaining precise , as arsenic's is about 50 times higher than gallium's at the , necessitating slightly As-rich initial charges (As/Ga ratio slightly above 1) and careful pressure control to avoid deviations that lead to point defects or compensation effects. Additionally, crucible interactions pose contamination risks, particularly from (SiO₂) in HB and VGF, where silicon incorporation can alter electrical properties; PBN crucibles mitigate this in VGF, while B₂O₃ encapsulation in LEC reduces but does not eliminate inclusions. Impurity incorporation during growth, such as unintentional doping, influences carrier compensation but is managed through melt purification prior to pulling.

Purification and Wafer Preparation

High-purity gallium and arsenic precursors are essential for producing GaAs crystals with minimal defects and optimal electronic properties. Gallium is typically purified through zone refining, a process that involves melting a narrow zone of the metal and moving it along the length of the ingot, leveraging the segregation of impurities into the liquid phase to achieve ultra-high purity levels below 1 ppb for key contaminants such as silicon, oxygen, and carbon. Arsenic, often handled as arsenic trichloride (AsCl3) or trioxide, undergoes fractional distillation under vacuum to separate volatile impurities, resulting in purity exceeding 99.9999% and impurity concentrations under 1 ppb for elements like selenium and tellurium critical to GaAs performance. Following crystal growth techniques such as or liquid-encapsulated Czochralski (LEC), the resulting GaAs ingots are processed into wafers. Ingots are sliced into thin wafers using inner-diameter (ID) diamond saws, producing thicknesses typically between 200 and 600 µm to balance mechanical stability and device integration requirements. Subsequent mechanical with diamond abrasives removes saw damage and achieves initial flatness, followed by chemical-mechanical polishing (CMP) using slurries containing oxidants and etchants to yield surface roughness below 1 nm RMS, ensuring epi-ready surfaces free of subsurface defects. Semi-insulating GaAs wafers, widely used for high-frequency applications, exhibit resistivity in the range of 10^7 to 10^9 Ω·cm, achieved through controlled mid-gap Fermi levels without intentional doping. Common orientations include (100) for epitaxial compatibility and (111) for specific optical uses, with diameters up to 150 mm supporting production yields around 70% after processing to account for edge losses and defects. Recent advancements include 2024 developments in synthesis for GaAs quantum dots, where inorganic salt media replace organic solvents to enable higher-temperature reactions for cleaner, more uniform nanocrystals.

Processing Techniques

Etching and Patterning

and patterning of gallium arsenide (GaAs) are essential for fabricating - and nanoscale features in electronic and optoelectronic devices, allowing precise control over material removal to define device structures such as mesas, gates, and vias. These processes leverage both wet chemical , which relies on isotropic or anisotropic dissolution in solutions, and dry plasma-based , which provides directionality through bombardment. The choice of method depends on requirements for etch rate, surface quality, sidewall profile, and selectivity to underlying layers in heterostructures. Wet methods are simpler and cost-effective for larger features but often introduce undercutting, while dry techniques enable high-resolution patterning with vertical sidewalls, though they require vacuum equipment and careful control to avoid plasma-induced damage. Wet etching of GaAs commonly uses a mixture of phosphoric acid, hydrogen peroxide, and water in a 1:1:10 volume ratio (H₃PO₄:H₂O₂:H₂O), which etches anisotropically at rates of approximately 0.2–0.5 µm/min at room temperature, depending on orientation and solution freshness. This etchant preferentially attacks the (100) plane and is widely adopted for mesa formation in GaAs-based transistors due to its moderate selectivity and ability to reveal crystallographic defects. For applications demanding smoother surfaces, such as optical waveguides, citric acid/hydrogen peroxide solutions (e.g., 50:1 volume ratio of 50% citric acid to 30% H₂O₂) are employed, yielding etch rates as low as 6 nm/min while achieving root-mean-square surface roughness below 4 nm, significantly reducing scattering losses compared to phosphoric-based etchants. These wet processes are typically performed at ambient conditions and stopped by rinsing, but their isotropic components can lead to lateral etching, limiting feature fidelity below 1 µm. Dry etching techniques, particularly (RIE) in Cl₂/BCl₃ plasmas, offer superior control for high-aspect-ratio features, with etch rates ranging from 100–500 nm/min and greater than 90%, resulting in near-vertical sidewalls critical for dense interconnects. The chlorine-based chemistry forms volatile GaCl₃ and AsCl₃ byproducts, while BCl₃ enhances sidewall passivation via deposits, minimizing formation and improving uniformity across wafers up to 150 mm in . Compared to wet methods, RIE reduces undercutting but can introduce or charging effects, necessitating optimization of bias voltage (typically 100–300 V) and pressure (5–20 mTorr) for damage-free in high-frequency devices. Photolithography is the standard for patterning GaAs, where masks define features transferred via lift-off for evaporated metals (e.g., AuGe/Ni/Au ohmic contacts) or reactive for / layers, enabling resolutions down to 100 nm with deep-ultraviolet exposure tools. Lift-off avoids direct of the substrate but is limited to low-temperature deposits to prevent resist reflow, whereas reactive provides better adhesion for multilevel stacks but requires precise endpoint detection to prevent over-. Wet in photolithographic patterning often suffers from undercutting, where lateral etch rates approach 50–80% of vertical rates, distorting submicron features; this is mitigated by timed etches or dry alternatives for critical dimensions below 500 nm. Selective is particularly important for GaAs/AlGaAs heterostructures, where processes must stop abruptly on aluminum-containing layers to preserve interface integrity in devices. /H₂O₂ solutions (e.g., 1.5:1 ratio) achieve selectivities exceeding 100:1 for GaAs over Al₀.₃Ga₀.₇As, halting due to the formation of a passivating Al₂O₃ layer on the AlGaAs surface, enabling uniform recess depths with variations below 2 nm across wafers. This method, often combined with thin (5–10 nm) AlGaAs etch-stop layers grown by , supports the fabrication of high-electron-mobility transistors and lasers by ensuring smooth, defect-free stops without dry etch damage.

Semi-Insulating GaAs Production

Semi-insulating gallium arsenide (GaAs) is produced to achieve high electrical resistivity, typically in the range of 10^7 to 10^9 Ω·cm, making it suitable as a substrate material that minimizes parasitic currents in integrated circuits and high-frequency devices. This high resistivity is engineered through the introduction of deep-level defects that compensate shallow dopants and pin the near the mid-gap, effectively isolating the material electrically. The primary methods involve defect engineering during , with the liquid-encapsulated Czochralski (LEC) technique commonly used as the base process, supplemented by alternative growth optimizations and intentional doping. One widely adopted approach is EL2 defect engineering, where controlled arsenic-rich conditions during LEC growth promote the formation of the EL2 deep donor defect, an arsenic antisite (As_Ga) that pins the at mid-gap to enable semi-insulating behavior. The EL2 concentration, typically around 10^16 to 10^17 cm^{-3}, is tuned by adjusting the Ga-As melt stoichiometry to ensure uniform distribution and achieve resistivities exceeding 10^8 Ω·cm across the crystal. As a deep-level impurity, EL2 compensates residual shallow donors and acceptors, providing stable electrical isolation without the need for additional doping, though its formation can be influenced by post-growth annealing to enhance homogeneity. Chromium doping represents an alternative or complementary method, where Cr atoms at concentrations of 10^{16} to 10^{17} cm^{-3} introduce deep acceptor traps (e.g., at approximately 0.76 eV above the valence band) that capture electrons and increase resistivity to semi-insulating levels. This doping is incorporated during growth via vapor phase epitaxy or LEC, compensating native impurities effectively, but it introduces challenges such as light sensitivity due to photoionization of Cr^{2+} states, leading to transient photocurrents and potential instability under illumination. Despite these issues, Cr-doped GaAs has been used in early semi-insulating substrates, though it is less favored today compared to undoped EL2-based materials due to uniformity concerns. The vertical gradient freeze (VGF) method optimizes semi-insulating GaAs production by employing lower thermal gradients (typically <25°C/cm) than traditional LEC, reducing thermal stresses and dislocation densities to below 10^3 cm^{-2}, which improves electrical uniformity and yield. In growth, a multizone furnace enables controlled directional solidification without crucible rotation, resulting in crystals with consistent EL2 distributions and resistivities around 10^8 Ω·cm, alongside higher electron mobilities up to 5500 cm^2/V·s. Metrology for verifying semi-insulating properties relies on Hall effect measurements, which determine resistivity and carrier mobility using the van der Pauw configuration with low-current sourcing (down to 1 nA) to handle high-resistance samples, confirming values in the 10^7 to 10^9 Ω·cm range. Capacitance-voltage (C-V) profiling complements this by assessing net doping profiles through , deriving ionized impurity concentrations from depletion width variations and ensuring mid-gap pinning with resolutions down to ~0.4 nm for high-dopant densities, though adapted for semi-insulating to verify low carrier levels.

Applications in Electronics

High-Frequency Transistors and Amplifiers

Gallium arsenide (GaAs) plays a pivotal role in high-frequency transistors and amplifiers, particularly in radio frequency (RF) and microwave devices essential for high-speed wireless communications. Metal-semiconductor field-effect transistors (MESFETs) based on GaAs feature a Schottky barrier gate on a doped n-type channel, leveraging the material's high electron mobility to achieve operation beyond 2 GHz, surpassing silicon-based alternatives in microwave regimes. These structures provide robust performance in early RF applications, though they have largely been supplanted by more advanced heterostructures for ultra-high frequencies. High-electron-mobility transistors (HEMTs) represent a cornerstone of GaAs technology, utilizing AlGaAs/GaAs heterojunctions to confine electrons in a two-dimensional electron gas (2DEG) at the interface, which minimizes scattering and enhances carrier transport. This configuration enables cutoff frequencies (f_T) exceeding 100 GHz, with representative devices achieving f_T > 145 GHz in 0.1 μm gate-length pseudomorphic HEMTs (pHEMTs). Noise figures below 1 dB at 10 GHz are attainable, supporting low-noise amplification in and cellular systems. The superior in GaAs underpins these high f_T values, facilitating rapid switching and at frequencies. Pseudomorphic HEMTs (pHEMTs) and metamorphic HEMTs (mHEMTs) extend GaAs capabilities into and emerging applications through strained InGaAs channels and lattice-relaxed metamorphic buffers, respectively. pHEMTs deliver power densities of 1-2 W/mm, as demonstrated in devices with 1.1 W/mm at 10 GHz, enabling compact power amplifiers for base stations. Efficiencies surpass 50% at 28 GHz, with peak power-added efficiency (PAE) reaching 50% in designs, optimizing energy use in mm-wave transceivers. mHEMTs, optimized for frequencies above 100 GHz, support terahertz links by maintaining high gain and linearity in metamorphic InGaAs channels on GaAs substrates. Traveling-wave amplifiers (TWAs) in GaAs exploit distributed topologies to achieve amplification, with cascaded structures providing up to 20 dB gain over multi-octave bandwidths from 0.5 to 22 GHz. These (MMICs) offer flat gain responses and are deployed in systems for target detection and communications for signal boosting in Ka-band links. Recent advancements integrate GaN heterostructures, typically on Si or substrates, for enhanced RF performance in power amplifiers. While imec's 2025 demonstrations focus on GaN-on-Si with 66% PAE and 1 /mm output at 13 GHz, these approaches leverage the mature GaAs ecosystem for improved thermal management and compatibility in mobile RF front-ends via hybrid integration.

Digital Integrated Circuits

Gallium arsenide (GaAs) has been employed in digital integrated circuits (ICs) primarily for high-speed logic applications, leveraging its superior electron mobility compared to silicon to achieve faster switching speeds in computing and signal processing tasks. Early developments focused on metal-semiconductor field-effect transistor (MESFET) technologies, which enabled sub-100 ps gate delays suitable for advanced computing systems. These circuits found niche use in supercomputing during the 1980s and 1990s, though adoption was limited by manufacturing challenges. More recently, GaAs-based heterojunction bipolar transistors (HBTs) and mixed-signal ICs have extended its role into telecommunications infrastructure. One of the foundational GaAs digital logic families is enhancement/depletion-mode (E/D) MESFET logic, which uses paired enhancement-mode (normally off) and depletion-mode (normally on) transistors to form inverter and other basic logic elements. This approach allows for direct-coupled FET logic (DCFL) with low power consumption and high speed. For instance, submicron E/D-MESFET circuits with 0.2 µm lengths have demonstrated propagation delays as low as 8.1 ps per at a supply voltage of 1.0 V, with a power dissipation of 1.7 mW per , yielding a power-delay product of approximately 14 fJ. Such performance surpassed contemporary technologies, enabling clock rates up to 4 GHz in divider circuits and supporting complex MSI (medium-scale integration) functions like static . GaAs E/D-MESFET logic was notably integrated into the Cray-3 , the first major system to use GaAs ICs for all logic circuitry, achieving peak performance of 16 GFLOPS through gallium arsenide-based processors operating at elevated speeds. GaAs HBTs, particularly InGaP/GaAs variants, further advanced high-speed digital applications by combining bipolar transistor characteristics with bandgaps for improved current gain and . These devices exhibit cutoff frequencies (f_T) exceeding 100 GHz, with some structures reaching up to 160 GHz, enabling logic gates with switching speeds suitable for ultra-fast computing. InGaP/GaAs HBTs were explored for digital ICs in the late 1980s and 1990s, offering advantages in power efficiency over MESFETs for certain logic families, though their primary impact was in mixed-signal domains. Their high f_T facilitated integration in early high-performance systems, building on the GaAs foundation laid by MESFETs in projects like the series. Despite these advances, GaAs digital ICs faced significant challenges, including substantially higher production costs—estimated at about 5 times more expensive for wafers compared to due to material scarcity and complex epitaxial growth processes—which restricted them to specialized markets. Additionally, while GaAs offers inherent radiation hardness beneficial for space applications, with superior tolerance to from cosmic rays compared to (due to shorter minority carrier lifetimes and higher displacement thresholds), achieving consistent semi-insulating substrates for large-scale digital integration proved difficult. These hurdles contributed to commercial setbacks, such as the 1995 bankruptcy of Cray Computer Corporation, whose GaAs-based efforts, including the Cray-3, could not compete economically with alternatives. In modern applications, GaAs digital and mixed-signal ICs persist in high-frequency environments like base stations, where HBT and pseudomorphic (pHEMT) technologies handle digital predistortion, logic, and data conversion with low noise and high linearity. For example, 0.15 µm GaAs pHEMT processes support 20-60 GHz operations for mmWave front-ends, integrating digital control circuits for efficient . To mitigate cost and compatibility issues, heterogeneous integration techniques such as transfer printing have emerged, allowing GaAs devices to be precisely bonded onto platforms without epitaxial mismatch, enabling hybrid circuits for enhanced performance in and communications. This approach preserves GaAs's speed advantages while leveraging silicon's scalability, as demonstrated in printed GaAs photodetectors and logic elements on waveguides.

Comparison with Silicon

Advantages of GaAs over Silicon

Gallium arsenide (GaAs) exhibits superior compared to (Si), with values reaching approximately 8500 cm²/V·s at versus 1500 cm²/V·s for Si, representing roughly a sixfold increase. This enhanced mobility facilitates faster carrier transport, enabling GaAs-based transistors to achieve cutoff frequencies (f_T) that are higher than those in equivalent Si devices, which supports applications requiring rapid switching and high-speed performance. Additionally, the higher mobility contributes to lower noise figures in radiofrequency (RF) circuits, making GaAs preferable for low-noise amplifiers and high-frequency systems where is critical. Unlike silicon's indirect bandgap, GaAs possesses a direct bandgap of 1.42 eV, which allows for more efficient radiative recombination and emission or absorption processes essential in optoelectronic devices such as lasers and photodetectors. GaAs also demonstrates greater radiation tolerance than Si, attributed to its displacement threshold energies averaging approximately 13 eV (similar to Si's ~13 eV but with better defect recovery in practice), resulting in fewer persistent defects under particle and better suitability for and high-radiation environments. In terms of thermal performance, GaAs supports reliable operation at elevated temperatures up to 300 °C, far exceeding silicon's practical limit of about 150 °C, due to its wider bandgap that reduces intrinsic carrier generation at high temperatures. This property, combined with GaAs's higher breakdown (approximately 4 × 10^5 V/cm versus 3 × 10^5 V/cm for Si), enables robust with greater voltage handling and efficiency in demanding thermal conditions. Furthermore, GaAs features a low surface recombination velocity, often below 10^3 cm/s with proper passivation, which minimizes carrier losses at interfaces and enhances the efficiency of detectors and solar cells.

Advantages of Silicon over GaAs

Silicon remains the dominant material for most semiconductor applications due to its significantly lower production costs compared to gallium arsenide. GaAs wafers are typically 5-10 times more expensive than equivalent silicon wafers, primarily because of the rarity and higher processing demands of gallium and arsenic. This cost disparity is exacerbated by the mature silicon manufacturing ecosystem, which supports wafer diameters up to 300 mm in high-volume fabrication facilities, enabling economies of scale that GaAs production, limited to a maximum of 150 mm wafers, cannot match. Although silicon's indirect bandgap limits its efficiency in optoelectronic devices, it offers superior thermal conductivity of approximately 1.5 W/· compared to GaAs's 0.46 W/·, allowing better heat dissipation in densely packed circuits. Additionally, silicon's abundance in the —at 28.2% by mass—far exceeds that of (0.0019%) and (0.00015%), ensuring a stable and inexpensive supply chain for large-scale production. Silicon's well-established processing techniques facilitate easier integration for large-scale integrated circuits, supporting billions of transistors per chip with lower defect densities in production, typically below 10^4 cm⁻², compared to GaAs's higher variability and densities often exceeding 10^6 cm⁻² in certain epitaxial layers such as those grown on Si substrates due to lattice mismatch. Recent advancements in , such as hybrid integration of GaAs nano-ridge lasers on 300 mm silicon wafers, further reduce reliance on standalone GaAs substrates by leveraging silicon's scalability for optoelectronic applications.

Optoelectronic Applications

Light-Emitting Diodes and Lasers

Gallium arsenide (GaAs) light-emitting diodes (LEDs) leverage a double heterostructure configuration, typically featuring an active GaAs layer sandwiched between AlGaAs cladding layers, to achieve efficient carrier and optical confinement. This design enables emission wavelengths in the 850-900 nm near- range, with external quantum efficiencies surpassing 20% through enhanced light extraction techniques such as photon recycling. The direct bandgap property of GaAs (~1.42 eV at ) underpins the high radiative efficiency of these devices, making them suitable for applications requiring compact, reliable sources. GaAs-based lasers, including vertical-cavity surface-emitting lasers (VCSELs) and edge-emitting variants, commonly incorporate active regions within AlGaAs/GaAs heterostructures to support low-loss waveguiding and . These structures routinely demonstrate threshold currents below 1 mA and continuous-wave output powers ranging from 1 to 10 mW, facilitated by precise control over thickness and composition for emission near 850 nm. These GaAs optoelectronic devices play a pivotal role in fiber optic communications, where 850 nm VCSELs drive short-reach datacom links over multimode fibers for distances up to 100 m, supporting data rates exceeding 100 Gb/s in parallel optical interconnects. Additionally, GaAs lasers serve as efficient pump sources for solid-state lasers, such as Nd:YAG systems, by delivering high-power output at wavelengths matching absorption bands around 808-850 nm to enable compact, high-brightness operation.

Solar Cells and Photodetectors

Gallium arsenide (GaAs) solar cells are prized for their high efficiency in converting to , particularly applications and concentrator systems, due to GaAs's bandgap of approximately 1.42 eV, which aligns well with the solar . These cells outperform in radiation resistance and temperature stability, enabling reliable performance in harsh environments. Single-junction GaAs cells typically achieve efficiencies of 26-28% under AM1.5 global conditions, with record values reaching 29.1% as confirmed by independent measurements. Multi-junction GaAs-based cells stack materials like InGaP (top), GaAs (middle), and Ge (bottom) in lattice-matched configurations to capture a broader , achieving efficiencies up to ~34% under one-sun AM1.5 illumination. Metamorphic multi-junction variants, such as InGaP/GaAs/GaInNAsSb, have attained a record 39.5% efficiency under one-sun AM1.5, as verified by the U.S. Department of Energy and National Renewable Energy Laboratory (NREL) in 2022. For space-grade applications, these cells achieve efficiencies around 28-32% under the AM0 with high specific power exceeding 3000 W/kg; Emcore Corporation reported advancements in 2024 enhancing performance for satellite missions. Thin-film and flexible GaAs variants reduce weight and cost while maintaining high performance, suitable for wearable or deployable solar arrays. In 2023, researchers achieved 23.1% in a thin-film GaAs cell using electrochemical porosification to separate epitaxial layers from a Ge substrate, enabling reuse and lightweight designs. Recent innovations, such as ordered nano-conical arrays on GaAs surfaces, have demonstrated enhanced light trapping, boosting short-circuit current density by up to 15% and overall in 2025 simulations and prototypes. GaAs photodetectors leverage the material's fast carrier mobility for high-speed light sensing in and . PIN photodiodes offer responsivities around 0.8 A/W at 850 nm, with low dark currents under reverse bias. Avalanche photodiodes (APDs) provide internal gain for weak signals, achieving bandwidths exceeding 50 GHz, as seen in GaAs-based designs optimized for 850 nm operation. The market for GaAs solar cells, driven by and high-efficiency terrestrial demand, was valued at approximately $17 billion in , with projections reaching $34 billion by 2032 at a of over 8%. NREL's best research-cell efficiencies for GaAs-based technologies, updated through July 2025, continue to set benchmarks, with multi-junction cells leading at 39.5% for one-sun and over 47% under concentration for advanced configurations.

Emerging Applications

Quantum Technologies

Gallium arsenide (GaAs) plays a pivotal role in quantum technologies through its integration into structures like quantum dots and wells, enabling coherent quantum states for information processing. In GaAs/AlGaAs quantum dots, exciton qubits, particularly dark excitons, serve as long-lived matter qubits with lifetimes approaching 1 µs, making them suitable for applications in photonic quantum networks. These qubits are accessed optically via spin-blockaded biexciton states, exhibiting spin-precession periods around 0.82 ns and fine-structure splittings of about 5 µeV, which facilitate scalable processing such as entangled pair generation. Recent advancements include the 2024 development of a synthesis method using Ga[GaI₄] and AsI₃ precursors at 400–500°C, which enables scalable production of sub-10-nm GaAs quantum dots with size-tunable from 617 to 759 nm and narrow linewidths, overcoming previous limitations in high-temperature colloidal synthesis. Electron spin qubits in GaAs quantum wells represent another cornerstone, leveraging the material's of approximately -0.44 for precise control. These qubits, formed by confining single , achieve coherence times up to 0.608 µs through nuclear spin cooling techniques, mitigating from hyperfine interactions. Manipulation occurs via electron spin resonance (ESR), often at frequencies near 94 GHz in W-band setups, allowing coherent Rabi oscillations and gate operations essential for architectures. The fixed g-factor in GaAs enables electrically driven spin rotations with , positioning these systems as robust platforms for multi-qubit entanglement. GaAs-based acoustic resonators further enhance qubit interconnectivity by mediating coupling between spin qubits and other quantum systems. Surface acoustic wave (SAW) resonators in GaAs/AlGaAs heterostructures provide phonon-mediated interactions, with GaAs's acoustic wave speed roughly half that of (approximately 4700 m/s vs. 9000 m/s), which improves compatibility with superconducting qubits operating at cryogenic temperatures by reducing mode frequencies for easier matching. These resonators enable strong optomechanical to quantum dots, supporting hybrid quantum interfaces for coherent transfer of quantum states. Emerging research from 2023 to 2025 highlights GaAs's expanding frontiers in . At , efforts focus on droplet-etched GaAs for GHz-clocked entangled sources integrated into quantum repeaters and 5G-quantum networks, achieving high-efficiency emission for distributed . Concurrently, the University of Chicago's Talapin Lab has pioneered routes to novel III-V nanocrystals, including GaAs variants, unlocking previously inaccessible compositions for advanced emitters and sensors. These developments underscore GaAs's versatility in scaling quantum technologies toward practical quantum communication and computing.

Sensors and Other Uses

Gallium arsenide (GaAs) is utilized in optic temperature sensors due to its temperature-dependent bandgap, which enables precise non-contact measurements in harsh environments. These sensors operate by detecting the shift in the GaAs bandgap edge, approximately 0.4 nm per Kelvin, through or . This mechanism allows for a wide operational range from -200°C to 300°C with high accuracy, typically ±0.2 K, making them suitable for applications in power plants, oil wells, and medical devices where must be avoided. The inherent properties of GaAs, including its bandgap, facilitate reliable transduction without electrical connections to the sensing tip, enhancing durability in corrosive or explosive settings. In , GaAs-based Hall devices serve as efficient spin-charge converters, transforming spin currents into measurable charge signals at . These devices leverage the in GaAs s, where an applied generates a tunable transverse spin accumulation that is detected via the inverse , producing a Hall voltage. By the spin-orbit through asymmetric structures, researchers have achieved conversion efficiencies comparable to those in like , enabling practical spintronic logic and memory elements. This functionality positions GaAs Hall devices as key components for low-power, non-magnetic spin manipulation in future data processing technologies. Recent advancements have extended GaAs to , particularly through the development of thin-film structures for wearable and photovoltaic applications. A 2024 study from the demonstrated heteroepitaxial GaAs thin films grown on large-area, biaxially aligned, flexible metallic substrates using , achieving low defect densities (~10^8 cm^{-2}) and high electron mobilities up to 459 cm²/V·s. These films maintain single-crystal-like quality post-flexing, supporting integration into lightweight wearables for health monitoring and bendable solar cells with enhanced efficiency over rigid counterparts. The approach reduces costs by enabling , broadening GaAs use beyond traditional rigid substrates in portable . GaAs surfaces can be functionalized for biosensing applications, allowing selective detection of biomolecules through chemical attachment. Techniques such as self-assembled monolayers of alkanethiols or brushes enable stable immobilization of antibodies or receptors on GaAs, preserving its piezoelectric properties for label-free detection via shifts. For instance, ZnO/GaAs bulk sensors functionalized with specific ligands have shown regenerability and sensitivity for quantifying biological agents like viruses in liquid media. This surface modification exploits GaAs's and optoelectronic responsiveness, facilitating point-of-care diagnostics with minimal .

Safety and Environmental Considerations

Health Hazards

Gallium arsenide (GaAs) poses significant health risks primarily due to its content, with the International Agency for Research on Cancer (IARC) classifying it as a carcinogen, meaning it is to . This classification is based on sufficient evidence from animal studies showing GaAs induces lung tumors upon , and its solubility in bodily fluids releases bioavailable , a known human . of GaAs is particularly hazardous, as it can lead to pulmonary accumulation and increased risk of , with no safe threshold established for carcinogenic effects. Acute oral exposure to GaAs exhibits low toxicity, with an LD50 greater than 5000 mg/kg in rats, indicating minimal immediate lethality via ingestion. However, chronic exposure to from GaAs can cause systemic effects, including gastrointestinal disturbances such as , cramps, and , alongside potential skin lesions and peripheral characteristic of . Gallium components in GaAs contribute additional risks, primarily through and respiratory effects. of gallium fumes or dust can cause , a potentially life-threatening accumulation of fluid in the lungs, while skin contact may result in or . Chronic gallium exposure has been linked to neuropathy, manifesting as neurological pain and weakness, as observed in cases of industrial fume , and may also suppress function and the . In semiconductor manufacturing, primary exposure routes include of respirable dust generated during sawing or grinding, and potential generation of toxic gases like (AsH₃) during wet etching processes, where AsH₃ is highly toxic with an immediately dangerous to life or (IDLH) concentration of 3 ppm. and dermal absorption are less common but possible through poor practices in handling. Regulatory measures emphasize stringent controls to mitigate these hazards. The (OSHA) sets a (PEL) of 0.01 mg/m³ for inorganic compounds, including GaAs, measured as over an 8-hour time-weighted average, while the National Institute for Occupational Safety and Health (NIOSH) recommends a lower (REL) of 0.002 mg/m³ (15-minute ceiling) as . Handling GaAs requires (PPE) such as respirators, gloves, and protective clothing, along with local exhaust ventilation to prevent airborne dust and gas release.

Environmental Impact and Supply Chain

The production of gallium arsenide (GaAs) generates significant environmental challenges, particularly in management. During wafer polishing in chemical-mechanical planarization (CMP) processes, high concentrations of (As) and (Ga) are released into wastewater, with arsenic levels often reaching 1,800–2,400 mg/L due to the oxidative dissolution of GaAs material. These effluents pose risks to aquatic ecosystems if untreated, as arsenic is a that can bioaccumulate and disrupt microbial communities in receiving waters. Treatment typically involves chemical and methods, such as co-precipitation with iron or aluminum salts followed by adsorption, to remove over 95% of dissolved arsenic and gallium, enabling compliance with discharge standards. GaAs crystal growth is energy-intensive, contributing to a substantial . The liquid-encapsulated Czochralski (LEC) method, commonly used for producing high-quality GaAs , requires high-temperature furnaces operating at 1,200–1,500°C. Efforts to mitigate this include adopting sources for facilities and optimizing process parameters to reduce thermal losses. The GaAs is highly vulnerable due to geopolitical concentrations and restrictions. Approximately 98–99% of global primary production, a key precursor for GaAs, originates from as a byproduct of bauxite processing in alumina refineries. imposed controls on starting in July 2023, escalating to full bans on shipments to the by December 2024, which disrupted global supply chains and raised prices by over 50%. However, as of , 2025, suspended the ban on of (along with and ) to the , effective until November 27, 2026, potentially easing some supply pressures. In the , metal imports were valued at about $3 million in 2023, with total apparent consumption around 20 metric tons annually, underscoring heavy reliance on foreign sources. 's designation as a critical in the U.S. Geological Survey's 2025 List of Critical Minerals highlights these risks, prompting initiatives for domestic sourcing and stockpiling. Recycling rates for GaAs from remain low, exacerbating and waste generation. End-of-life recycling input rates are below 10%, with much of the material ending up in landfills due to the challenges of separating and from complex devices like LEDs and integrated circuits. The European Union's Restriction of Hazardous Substances (RoHS) Directive provides exemptions for GaAs in optoelectronic applications, such as LEDs and solar cells, to balance with technological needs, though these are periodically reviewed for renewal. Emerging hydrometallurgical and pyrometallurgical processes aim to improve recovery yields above 95% for both and , but scaling remains limited by economic viability.

References

  1. https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Chemistry_of_the_Main_Group_Elements_%28Barron%29/06%253A_Group_13/6.11%253A_Properties_of_Gallium_Arsenide
  2. https://parts.jpl.nasa.gov/mmic/3-I.PDF
  3. https://www.ncbi.nlm.nih.gov/books/NBK321691/
  4. https://www.nrel.gov/pv/cell-efficiency.html
  5. https://materialsproject.org/materials/mp-2534/
  6. https://www.ioffe.ru/SVA/NSM/Semicond/GaAs/basic.html
  7. https://www.ioffe.ru/SVA/NSM/Semicond/GaAs/thermal.html
  8. http://mateck.com/en/content/71-gallium-arsenide-gaas
  9. https://www.sciencedirect.com/science/article/pii/0022024884902641
  10. https://pubs.aip.org/aip/jap/article-pdf/73/1/477/18654398/477_1_online.pdf
  11. https://www.sciencedirect.com/science/article/abs/pii/S0169433221005651
  12. https://www.ioffe.ru/SVA/NSM/Semicond/GaAs/bandstr.html
  13. https://www.tydexoptics.com/pdf/GaAs.pdf
  14. https://www.ioffe.ru/SVA/NSM/Semicond/GaAs/electric.html
  15. https://pubs.aip.org/aip/jap/article/35/4/1241/164664/Refractive-Index-of-GaAs
  16. https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1141&context=ecepubs
  17. https://pubchem.ncbi.nlm.nih.gov/compound/Gallium-arsenide
  18. https://pubs.aip.org/avs/jva/article-pdf/7/1/49/11486813/49_1_online.pdf
  19. https://www.researchgate.net/publication/299244064_Studies_of_oxidation_on_GaAs100_surface_by_XPS
  20. https://joam.inoe.ro/articles/evolution-of-surface-oxides-on-gaas/fulltext
  21. https://pubmed.ncbi.nlm.nih.gov/2756869/
  22. https://www.allresist.com/resist-wiki-hf-etching-of-gaas-with-csar-62-masks/
  23. https://pearton.mse.ufl.edu/wp-content/uploads/sites/278/2020/07/david_hays_sel_etching_of_compound_semi.pdf
  24. https://ui.adsabs.harvard.edu/abs/1965JAP....36..308M/abstract
  25. https://www.sciencedirect.com/science/article/abs/pii/S0301479724000355
  26. https://www.sciencedirect.com/science/article/pii/0038110187901122
  27. https://link.aps.org/doi/10.1103/PhysRevLett.94.185501
  28. https://iopscience.iop.org/article/10.1088/1367-2630/ac1a98
  29. https://iopscience.iop.org/article/10.1088/0022-3719/6/11/008
  30. https://link.aps.org/doi/10.1103/PhysRevB.36.1332
  31. https://www.sciencedirect.com/science/article/pii/0254058482900050
  32. https://pubs.aip.org/avs/jvb/article-pdf/4/4/931/11630456/931_1_online.pdf
  33. http://amsacta.unibo.it/1729/1/GAAS_96_052.pdf
  34. https://pubs.aip.org/aip/jap/article/53/10/R123/11455/Semiconducting-and-other-major-properties-of
  35. https://chem.libretexts.org/Bookshelves/Inorganic_Chemistry/Chemistry_of_the_Main_Group_Elements_(Barron)/06%3A_Group_13/6.11%3A_Properties_of_Gallium_Arsenide
  36. https://pubs.aip.org/aip/apl/article/1/3/62/23064/STIMULATED-EMISSION-OF-RADIATION-FROM-GaAs-p-n
  37. https://archive.ll.mit.edu/publications/journal/pdf/vol02_no1/2.1.1.earlywork.pdf
  38. https://www.shmj.or.jp/english/discretescdvc/dsd70s.html
  39. https://bc.itl.waw.pl/Content/517/JTIT-2004_1_99.pdf
  40. https://archive.computerhistory.org/resources/access/text/2013/04/102723443-05-01-acc.pdf
  41. https://advanced.onlinelibrary.wiley.com/doi/10.1002/aelm.201600501
  42. https://anysilicon.com/gallium-arsenide-gaas-overview/
  43. https://pubs.usgs.gov/periodicals/mcs2024/mcs2024-gallium.pdf
  44. https://www.fastmarkets.com/insights/market-reacts-cautiously-to-chinas-immediate-export-control-on-certain-critical-metals/
  45. https://www.reuters.com/world/china/china-suspends-ban-exports-gallium-germanium-antimony-us-2025-11-09/
  46. https://viterbischool.usc.edu/news/2023/06/new-mpw-projects-on-gallium-nitride-and-gallium-arsenide-processes/
  47. https://doi.org/10.1016/S0022-0248(98)01208-1
  48. https://www.researchgate.net/publication/222143467_Bulk_growth_of_GaAs_An_overview
  49. https://www.osti.gov/servlets/purl/6055130
  50. https://www.sciencedirect.com/topics/chemical-engineering/gas-source-molecular-beam-epitaxy
  51. https://pubs.acs.org/doi/10.1021/acsomega.3c04777
  52. https://ntrs.nasa.gov/citations/19820034050
  53. https://www.sciencedirect.com/science/article/pii/0022024895002979
  54. https://www.sciencedirect.com/science/article/pii/0022024887904787
  55. https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1377&context=open_access_theses
  56. https://www.researchgate.net/publication/356651793_Processes_for_the_Preparation_of_High-Purity_Arsenic_and_Its_Compounds
  57. https://freiberger.com/en/technology/
  58. https://logitech.uk.com/wp-content/uploads/2025/06/GaAs-LP70-Application-Note_v2050719-3.pdf
  59. https://www.kemet.co.uk/blog/lapping/precision-lapping-and-polishing-of-wafers
  60. https://www.powerwaywafer.com/semi-insulating-gaas-substrate.html
  61. https://mtixtl.com/products/gaas-100-orientation-si-semi-insulating-undoped-5x5x-0-5mm-1sp
  62. https://pme.uchicago.edu/news/uchicago-researchers-unlock-new-synthetic-frontier-quantum-dots
  63. https://nanohub.org/resources/11674/download/Metal_Semiconductor_FET_MESFET.pdf
  64. https://www.microwavejournal.com/articles/28935-a-214-dbm-w-band-gaas-phemt-mmic-power-amplifier
  65. https://ietresearch.onlinelibrary.wiley.com/doi/full/10.1049/ell2.12445
  66. https://pubs.aip.org/aip/apr/article/11/3/031318/3308978/Gigahertz-and-terahertz-transistors-for-5G-6G-and
  67. https://ieeexplore.ieee.org/document/1213954/
  68. https://www.jhuapl.edu/Content/techdigest/pdf/V10-N04/10-04-Mehlem.pdf
  69. https://www.imec-int.com/en/press/imec-achieves-record-breaking-rf-gan-si-transistor-performance-high-efficiency-6g-power
  70. https://iopscience.iop.org/article/10.1143/JJAP.29.L2438
  71. https://web.eecs.utk.edu/~dbouldin/protected/tuyl-oct77.pdf
  72. https://archive.computerhistory.org/resources/access/text/2010/02/102685990-05-01-acc.pdf
  73. https://www.kenresearch.com/global-gallium-arsenide-gaas-wafer-market
  74. https://nepp.[nasa](/page/NASA).gov/docuploads/A6B8B953-E2DD-4D92-AB8A873A04F0B10A/NSREC02_SC_Poivey.pdf
  75. https://cray-history.net/2021/07/23/cash-starved-cray-computer-closes-seeks-chapter-11-march-27th-1995/
  76. https://gtigroup.org/Uploads/File/2022/03/14/u622ee135a8a1a.pdf
  77. https://ieeexplore.ieee.org/document/9252495
  78. https://eesemi.com/sigegaas.htm
  79. https://www.electronicsforu.com/technology-trends/tech-focus/emergence-gaas-devices-substitute-silicon
  80. https://www.spectrumcontrol.com/asset/gaas-transistors.pdf
  81. https://www.allaboutcircuits.com/news/gallium-arsenide-another-player-in-semiconductor-technology/
  82. https://www.cambridge.org/core/journals/journal-of-materials-research/article/computational-simulation-of-threshold-displacement-energies-of-gaas/F4EB2E32DD912345A77C01F6E9BF257A
  83. https://www.sciencedirect.com/topics/engineering/gaas-device
  84. https://www.universitywafer.com/choosing-semiconductor-materials.html
  85. https://pubs.aip.org/aip/apl/article/90/13/134102/920782/Surface-recombination-velocity-in-GaAs-and-In0
  86. https://www.ftsplasma.com/blog/2015/12/20/trends-in-semiconductor-manufacturing-process-equipment
  87. https://periodictable.com/Properties/A/CrustAbundance.an.html
  88. https://www.nature.com/articles/srep25328
  89. https://www.imec-int.com/en/press/first-full-wafer-scale-fabrication-electrically-pumped-gaas-based-nano-ridge-lasers-300-mm
  90. https://onlinelibrary.wiley.com/doi/10.1002/pip.3919
  91. https://www.nrel.gov/news/program/2022/nrel-creates-highest-efficiency-1-sun-solar-cell.html
  92. https://www.sciencedirect.com/science/article/abs/pii/S0038092X25000623
  93. https://www.coherent.com/content/dam/coherent/site/en/resources/datasheet/networking/850nm-14gbps-gaas-pin-photodiode.pdf
  94. https://opg.optica.org/prj/abstract.cfm?uri=prj-13-6-1438
  95. https://ganology.sist.shanghaitech.edu.cn/publication/High-Speed_46-GHz_850_nm_Photodetector_with_Inductive_Peaking.pdf
  96. https://www.databridgemarketresearch.com/reports/global-gallium-arsenide-germanium-solar-cell-gaas-market
  97. https://pubs.aip.org/aip/app/article/2/12/121303/122860/Accessing-the-dark-exciton-spin-in-deterministic
  98. https://www.science.org/doi/10.1126/science.ado7088
  99. https://link.aps.org/doi/10.1103/PhysRevLett.131.210805
  100. https://pubs.aip.org/aip/rsi/article/80/10/103102/354278/A-kilowatt-pulsed-94-GHz-electron-paramagnetic
  101. https://link.aps.org/doi/10.1103/PhysRevApplied.21.014015
  102. https://pmc.ncbi.nlm.nih.gov/articles/PMC4606810/
  103. https://www.ifw-dresden.de/ifw-institutes/iet/research/solid-state-quantum-photonics/research
  104. https://comem.com/wp-content/uploads/2024/10/Fiber-optic-FOTEMP_C15-COMEM-MA-A5-EN-24-10-2024.pdf
  105. https://www.micronor.com/products/files/TS3/MICRONOR_DS_TS3.pdf
  106. https://opsens-solutions.com/products/fiber-optic-temperature-sensors/otg-m-serie/
  107. https://press.uni-mainz.de/international-team-of-scientists-realizes-a-tunable-spin-charge-converter-made-of-gallium-arsenide/
  108. https://www.asianscientist.com/2014/09/in-the-lab/tuning-spin-hall-angle-cheaper-spintronics-2014/
  109. https://www.nature.com/articles/s41598-024-59686-0
  110. https://www.buffalo.edu/news/releases/2024/05/semiconductor-flexible-electronics.html
  111. https://pmc.ncbi.nlm.nih.gov/articles/PMC8151011/
  112. https://pubs.acs.org/doi/10.1021/acsomega.0c04954
  113. https://publications.iarc.who.int/_publications/media/download/2721/3de2f2fb9e2f19afb79ac97c68ff3c16785a6dba.pdf
  114. https://www.cdc.gov/niosh/docs/88-100/default.html
  115. https://prochemonline.com/wp-content/uploads/2021/06/1861.GalliumArsenide.pdf
  116. https://cores.research.utdallas.edu/files/2023/04/Gallium_Arsenide.pdf
  117. https://pubmed.ncbi.nlm.nih.gov/22024274/
  118. https://pmc.ncbi.nlm.nih.gov/articles/PMC2898053/
  119. https://www.gov.uk/government/publications/arsenic-hydride-properties-incident-management-and-toxicology/arsine-and-stibine-general-information
  120. https://stacks.cdc.gov/view/cdc/209501/cdc_209501_DS1.pdf
  121. https://www.osha.gov/chemicaldata/196
  122. https://www.cdc.gov/niosh/npg/npgd0038.html
  123. https://www.researchgate.net/publication/385174360_Sustainable_Solutions_for_Gallium_and_Arsenic_Extraction_from_semiconductor_industry_waste_-_A_comprehensive_review
  124. https://pmc.ncbi.nlm.nih.gov/articles/PMC12510042/
  125. https://www.researchgate.net/publication/271936384_Arsenic_removal_of_high-arsenic_wastewater_from_gallium_arsenide_semiconductor_production_by_enhanced_two-stage_treatment
  126. https://link.springer.com/article/10.1007/s11367-025-02492-1
  127. https://pubs.usgs.gov/periodicals/mcs2025/mcs2025-gallium.pdf
  128. https://www.csis.org/analysis/china-imposes-its-most-stringent-critical-minerals-export-restrictions-yet-amidst
  129. https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
  130. https://www.questmetals.com/blog/anthropogenic-gallium-cycle
  131. https://compoundsemiconductor.net/article/90733/SEMI_Highlights_The_Need_For_InP_And_GaAs
  132. https://www.mdpi.com/2304-6732/12/8/808
Add your contribution
Related Hubs
User Avatar
No comments yet.