Gallium arsenide GaAs

spore: profile
id: gallium-arsenide
spore_version: 0.2
family: semiconductor-materials
name: Gallium arsenide
abbreviation: GaAs
role: semiconductor
category: semiconductors
type: gaas
summary: |
  Gallium arsenide is a compound semiconductor, one gallium atom bonded to one arsenic atom, with a zinc-blende crystal. The sources read for this profile give a band gap of 1.424 eV at 300 K, electron mobility up to 8500 cm2/(V·s), and a density of 5.32 g/cm3. Spectrolab's space solar cells use GaAs-based multijunction designs, and a 1984 JPL study found GaAs cells lost much more power than silicon cells under 50 keV protons, though its authors judged GaAs cells to perform well in proton-dominated orbits.
best_for: Light emission, RF power and multijunction space solar cells, where the band gap and electron mobility of GaAs beat silicon (1.424 eV and up to 8500 cm2/(V·s))
weakest_at: 'Cost and toxicity: the arsenic content is classed as carcinogenic in GHS, and the gallium supply is concentrated in China (99% of primary low-purity gallium)'
identity:
  formula: GaAs, one gallium atom bonded to one arsenic atom (zinc-blende crystal)
  cas: 1303-00-0
  space_group: Td2-F43m (zinc blende)
  source: ioffe-basic
  where: Basic Parameters at 300 K table (crystal structure, group of symmetry); CAS from NIST WebBook (Chemistry WebBook, formula AsGa, CAS Registry Number 1303-00-0)
tags:
  environments:
    - geo
  stresses: []
  applications:
    - solar-arrays
    - electronics-and-chips
    - optics-and-cameras
properties:
  - benchmark: density
    label: Density
    value: 5.32
    unit: g/cm3
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: ioffe-basic
    where: Basic Parameters at 300 K table, row Density
  - benchmark: density
    label: Density (mechanical properties table)
    value: 5.317
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed in a materials property table
    status: ground
    source: ioffe-mechanic
    where: Mechanical properties table, Basic Parameter block, row Density
  - benchmark: density
    label: Density (table at 300 K)
    value: 5.32
    unit: g/cm3
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Density (g/cm3)
  - benchmark: lattice_constant
    label: Lattice constant
    value: 5.65325
    unit: Å
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: ioffe-basic
    where: Basic Parameters at 300 K table, row Lattice constant (printed as 5.65325 A)
  - benchmark: lattice_constant
    label: Lattice constant (table at 300 K)
    value: 5.6533
    unit: angstrom
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Lattice Constant (angstroms)
  - benchmark: melting_point
    label: Melting point
    value: 1240
    unit: °C
    scope: material
    conditions:
      basis: melting point as printed, no pressure stated
    method: Value printed in a materials property table
    status: ground
    source: ioffe-thermal
    where: Thermal properties table, row Melting point
  - benchmark: melting_point
    label: Melting point (table at 300 K)
    value: 1238
    unit: °C
    scope: material
    conditions:
      basis: melting point as printed, no pressure stated
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Melting Point (deg C)
  - benchmark: bandgap
    label: Energy band gap at 300 K
    value: 1.424
    unit: eV
    scope: material
    conditions:
      temperature: 300 K
    method: Value printed in a materials property table
    status: ground
    source: ioffe-bandstr
    where: Band structure and carrier concentration page, Basic Parameters block, row Energy gap (also printed as Eg = 1.42 eV in the band structure figure)
  - benchmark: bandgap
    label: Energy band gap at 300 K (table)
    value: 1.424
    unit: eV
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Energy Gap at 300K (eV)
  - benchmark: electron_mobility
    label: Electron drift mobility
    value: 8500
    unit: cm2/(V·s)
    scope: material
    conditions:
      temperature: 300 K (table title)
      type: drift mobility, doping not stated
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Mobility (Drift) n, electrons
  - benchmark: electron_mobility
    label: Electron mobility (upper limit for weakly doped material)
    value: 8500
    unit: cm2 V-1 s-1
    scope: material
    conditions:
      temperature: not stated on the page
      basis: printed as "≤8500", so this is an upper value
    method: Value printed in a materials property table
    status: ground
    source: ioffe-electric
    where: Electrical properties, Basic Parameters block, row Mobility electrons
  - benchmark: hole_mobility
    label: Hole drift mobility
    value: 400
    unit: cm2/(V·s)
    scope: material
    conditions:
      temperature: 300 K (table title)
      type: drift mobility, doping not stated
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Mobility (Drift) p, holes
  - benchmark: thermal_conductivity
    label: Thermal conductivity
    value: 0.46
    unit: W/(cm·°C)
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Thermal Conductivity at 300 K
  - benchmark: thermal_conductivity
    label: Thermal conductivity (no temperature stated)
    value: 0.55
    unit: W/(cm·°C)
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed in a materials property table
    status: ground
    source: ioffe-thermal
    where: Thermal properties table, row Thermal conductivity
  - benchmark: specific_heat
    label: Specific heat (table at 300 K)
    value: 0.35
    unit: J/(g·°C)
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Specific Heat (J/g-deg C)
  - benchmark: specific_heat
    label: Specific heat (no temperature stated)
    value: 0.33
    unit: J/(g·°C)
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed in a materials property table
    status: ground
    source: ioffe-thermal
    where: Thermal properties table, row Specific heat (printed as J g-1°C -1)
  - benchmark: cte
    label: Linear thermal expansion (table at 300 K)
    value: 0.00000686
    unit: 1/°C
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Linear Coefficient of Thermal Expansion (printed as 6.86 x 10-6)
  - benchmark: cte
    label: Linear thermal expansion (no temperature stated)
    value: 0.00000573
    unit: 1/°C
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed in a materials property table
    status: ground
    source: ioffe-thermal
    where: Thermal properties table, row Thermal expansion, linear (printed as 5.73·10-6)
  - benchmark: dielectric_constant
    label: Dielectric constant (static)
    value: 12.9
    unit: dimensionless
    scope: material
    conditions:
      frequency: static
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: ioffe-basic
    where: Basic Parameters at 300 K table, row Dielectric constant (static)
  - benchmark: dielectric_constant
    label: Dielectric constant (table at 300 K)
    value: 13.1
    unit: dimensionless
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Dielectric Constant
  - benchmark: bulk_modulus
    label: Bulk modulus
    value: 753000000000
    unit: dyn/cm2
    scope: material
    conditions:
      temperature: not stated on the page
    method: Value printed in a materials property table
    status: ground
    source: ioffe-mechanic
    where: Mechanical properties table, Basic Parameter block, row Bulk modulus (printed as 7.53·10^11 dyn cm-2)
  - benchmark: poissons_ratio
    label: Poisson ratio
    value: 0.31
    unit: dimensionless
    scope: material
    conditions:
      temperature: 300 K
      direction: '100'
    method: Value printed in a materials property table
    status: ground
    source: ioffe-mechanic
    where: Elastic constants block at 300 K, row [100] Poisson ratio
  - benchmark: intrinsic_carrier_concentration
    label: Intrinsic carrier concentration (table at 300 K)
    value: 1790000
    unit: cm-3
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: eesemi
    where: Table at 300 deg K, column GaAs, row Intrinsic Carrier Concentration (printed as 1.79 x 10^6)
  - benchmark: intrinsic_carrier_concentration
    label: Intrinsic carrier concentration (band structure page)
    value: 2100000
    unit: cm-3
    scope: material
    conditions:
      temperature: 300 K
    method: Value printed in a materials property table
    status: ground
    source: ioffe-bandstr
    where: Band structure page, Basic Parameters block, row Intrinsic carrier concentration (printed as 2.1·10^6)
  - benchmark: electrical_resistivity
    label: Intrinsic resistivity
    value: 330000000
    unit: Ω·cm
    scope: material
    conditions:
      temperature: 300 K
      doping: intrinsic
    method: Value printed in a materials property table
    status: ground
    source: ioffe-bandstr
    where: Band structure page, Basic Parameters block, row Intrinsic resistivity (printed as 3.3·10^8)
  - benchmark: refractive_index
    label: Infrared refractive index
    value: 3.3
    unit: dimensionless
    scope: material
    conditions:
      temperature: 300 K
      wavelength: infrared (wavelength not stated in the table row)
    method: Value printed in a materials property table
    status: ground
    source: ioffe-optic
    where: Optical properties page, row Infrared refractive index (formula gives n = 3.299 at 300 K)
  - benchmark: electron_affinity
    label: Electron affinity
    value: 4.07
    unit: eV
    scope: material
    conditions:
      temperature: 300 K (table title)
    method: Value printed in a materials property table
    status: ground
    source: ioffe-basic
    where: Basic Parameters at 300 K table, row Electron affinity
  - benchmark: breakdown_field
    label: Breakdown field
    value: 400000
    unit: V/cm
    scope: material
    conditions:
      basis: printed as approximately 4·10^5 V/cm
    method: Value printed in a materials property table
    status: ground
    source: ioffe-electric
    where: Electrical properties, Basic Parameters block, row Breakdown field
  - benchmark: efficiency_am0
    label: Efficiency, GaInP/GaAs/Ge ultra-triple-junction (max power, AM0)
    value: 28.3
    unit: '%'
    scope: cell
    conditions:
      device: GaInP/GaAs/Ge multijunction (GaAs is the middle junction)
      illumination: AM0, 135.3 mW/cm2, 28 °C
      basis: highest power device, printed as over 28.3%
    method: Value printed in a conference paper by the manufacturer
    status: ground
    source: spectrolab-nasa
    where: Introduction, paragraph on the Ultra-Triple Junction (UTJ) product
  - benchmark: efficiency_am0
    label: Efficiency, GaInP/GaAs/Ge triple junction (on orbit since 2001, beginning of life)
    value: 25.1
    unit: '%'
    scope: cell
    conditions:
      device: GaInP/GaAs/Ge triple junction (TJ)
      illumination: AM0
      basis: beginning of life, printed in the paper
    method: Value printed in a conference paper by the manufacturer
    status: ground
    source: spectrolab-nasa
    where: Introduction, paragraph on the Triple Junction (TJ) product line
  - benchmark: efficiency_am0
    label: Efficiency, dual-junction GaInP/GaAs (first commercial satellite, 1997, beginning of life)
    value: 21.5
    unit: '%'
    scope: cell
    conditions:
      device: GaInP/GaAs dual junction (DJ)
      illumination: AM0
      basis: beginning of life, printed in the paper
    method: Value printed in a conference paper by the manufacturer
    status: ground
    source: spectrolab-nasa
    where: Introduction, paragraph on the first commercial multijunction satellite (Hughes HS 601HP, 1997)
  - benchmark: maximum_power_loss
    label: Maximum power loss, GaAs cells under 50 keV protons
    value: 40
    unit: '%'
    scope: cell
    conditions:
      particle: protons, 50 keV
      basis: approximately 40% loss as printed; the report does not give the fluence in the passage read
    method: Experimental irradiation of LPE p/n GaAs cells, reported in the JPL study
    status: ground
    source: nasa-jpl-84-61
    where: Section on GaAs cell results, 50 keV proton bombardment paragraph
  - benchmark: short_circuit_current_loss
    label: Short-circuit current loss, GaAs cells under 50 keV protons
    value: 30
    unit: '%'
    scope: cell
    conditions:
      particle: protons, 50 keV
      basis: printed as 30% of initial Isc
    method: Experimental irradiation of LPE p/n GaAs cells, reported in the JPL study
    status: ground
    source: nasa-jpl-84-61
    where: Section on GaAs cell results, 50 keV proton bombardment paragraph (silicon cells did not lose Isc at low proton energy in the same study)
  - benchmark: damage_coefficient_ratio
    label: Maximum-power damage coefficient, GaAs relative to silicon, 150 keV protons
    value: 30
    unit: x silicon
    scope: cell
    conditions:
      particle: protons, 150 keV
      incidence: normal
      basis: printed as a factor of 30 higher than for silicon at 150 keV
    method: Derived damage coefficients from proton irradiation, relative to 10 MeV protons
    status: ground
    source: nasa-jpl-84-61
    where: Discussion of normal-incidence Pm damage coefficients, Figure 30 text
story:
  recipe:
    line: |
      GaAs is a compound of one gallium atom and one arsenic atom in a 1:1 ratio, forming a zinc-blende crystal. Each element's standard atomic weight is taken from NIST. The composition is fixed by stoichiometry, not by a recipe with process steps read in this run.
    parts:
      - name: Gallium
        symbol: Ga
        atoms: 1
        atomic_weight: 69.723
        role: The group III element. Gallium supplies the metal sites of the zinc-blende lattice, and its supply is concentrated in China.
      - name: Arsenic
        symbol: As
        atoms: 1
        atomic_weight: 74.921595
        role: The group V element. Arsenic occupies the other sublattice, and it is the main source of the substance's toxicity.
  risk_groups:
    - title: For people
      level: 2
      verdict: Hazardous, carcinogenic
      lead: PubChem's GHS entry for GaAs (CAS 1303-00-0) carries carcinogen, reproductive and organ-damage hazard statements, and its toxicity is attributed to the arsenic it contains.
      points:
        - label: GHS statements
          line: H350 (may cause cancer), H360F (may damage fertility) and H372 (causes damage to organs through prolonged or repeated exposure), H350 and H372 each in 88.4% of the company reports and H360 in 50.9%, with 6.2% (7 of 112) reporting no hazard.
        - label: Exposure limits
          line: NIOSH gives a 15-minute ceiling for inorganic arsenic compounds, OSHA an 8-hour limit as As, and ACGIH lists arsenic and inorganic compounds as A1, a confirmed human carcinogen (see the mitigations entry for the figures).
    - title: If it fails
      level: 1
      verdict: Dust and acid release arsine
      lead: Reactions with steam, acids and acid fumes can release arsine, a highly toxic gas.
      points:
        - label: Arsine
          line: PubChem says GaAs can react with steam, acids and acid fumes to evolve the deadly poisonous arsine, and that molten GaAs attacks quartz.
    - title: Handling and storage
      level: 1
      verdict: Keep away from acids and steam
      lead: The sources read give storage advice for arsenic compounds generally, which applies to GaAs.
      points:
        - label: Storage
          line: 'PubChem''s advice for inorganic arsenic compounds: store in a well-ventilated area away from food and combustible materials, and protect the container from physical damage.'
  why: Gallium arsenide is the compound semiconductor used in multijunction space solar cells and in RF power amplifiers for cellular handsets. The sources read give a band gap of 1.424 eV at 300 K, electron mobility up to 8500 cm2/(V·s), and a melting point of 1238 to 1240 °C. Its arsenic content sets the hazard profile.
  uses:
    - where: Space solar cells
      line: Spectrolab's space solar cells use a GaInP/GaAs/Ge multijunction design, and the paper reports efficiencies of 21.5% (dual junction, 1997), 25.1% (triple junction) and over 28.3% (ultra-triple junction, AM0). It states that the design powers GEO missions up to a possible 30 kW on a single satellite.
    - where: Cellular handset RF amplifiers
      line: USGS says GaAs power amplifiers are used in cellular handsets, and that silicon CMOS power amplifiers compete with them in midtier 3G handsets.
    - where: Optoelectronics and defence
      line: USGS lists GaAs as the material for compound semiconductor wafers used in integrated circuits and optoelectronic devices, including laser diodes, LEDs, photodetectors and solar cells, and says GaAs and GaN ICs have no effective substitutes in many defence applications.
  can_do:
    - label: Carry electrons fast
      value: '8500'
      benchmark: electron_mobility
      line: Electron drift mobility is 8500 cm2/(V·s) at 300 K in eesemi's table, which lists a lower value for silicon in the same table.
    - label: Absorb and emit at a wide band gap
      value: '1.424'
      benchmark: bandgap
      line: The band gap is 1.424 eV at 300 K in two sources, which sits above silicon's value in the same table and suits photon emission and multijunction cells.
    - label: Hold up in orbit, with a cost
      value: '30'
      benchmark: damage_coefficient_ratio
      line: At 150 keV the maximum-power damage coefficient is 30 times silicon's. The study still judged GaAs cells to perform well in proton-dominated orbits.
  compare: Gallium arsenide has higher electron mobility and a wider band gap than silicon at 300 K, and a lower melting point and thermal conductivity. Under low-energy proton irradiation the 1984 JPL study found GaAs cells lost much more power than silicon cells, while the authors judged GaAs cells to perform well in proton-dominated orbits.
  compare_rows:
    - scope: material
      label: Electron mobility at 300 K
      benchmark: electron_mobility
    - scope: material
      label: Band gap at 300 K
      benchmark: bandgap
    - scope: material
      label: Thermal conductivity at 300 K
      benchmark: thermal_conductivity
  handling:
    - 'label: Dust and fumes line: Treat GaAs as a carcinogen-class material: keep dust down, use local exhaust ventilation, and use the exposure limits above. PubChem''s advice for arsenic compounds is to remove dust and ventilate, with positive-pressure breathing apparatus for firefighting.'
    - 'label: Keep away from acids line: Do not expose GaAs to steam, acids or acid fumes, which can release arsine.'
  good_for:
    - 'label: High-efficiency space solar cells line: The GaInP/GaAs/Ge multijunction design reached 25.1% efficiency for the triple junction and over 28.3% for the ultra-triple junction, and the paper says it powers GEO satellites.'
    - 'label: High electron mobility devices line: The 8500 cm2/(V·s) electron mobility and 1.424 eV band gap make GaAs a standard choice for RF power amplifiers and optoelectronic devices, as USGS describes.'
  watch_out:
    - 'label: Arsenic content line: GHS classes GaAs as carcinogenic and toxic to reproduction, and the arsenic it contains is the cause, so handling is controlled.'
    - 'label: Radiation in orbit line: The JPL study found GaAs cells lost 30% of their short-circuit current and about 40% of maximum power under 50 keV protons, and it reported damage coefficients 30 times silicon''s at 150 keV.'
    - 'label: Supply concentration line: China produced 99% of primary low-purity gallium and supplied more than 90% of US arsenic metal imports, and its export controls on gallium, first imposed in the recent past and partly lifted, have affected US supply (USGS).'
  verdict: Gallium arsenide is well documented. Its band gap, mobility, density and melting point agree across two or more sources, and its space cell efficiencies come from a manufacturer. Its hazard data are from PubChem and its radiation data from a 1984 study, so both are dated or secondary. Supply is concentrated in China.
corrosion:
  - environment: Moist air at room temperature
    headline: Stable in dry air and tarnishes in moist air (PubChem)
    effect: PubChem's stability entry says GaAs is stable in dry air and tarnishes in moist air. It is insoluble in water.
    rating: low
    conditions:
      exposure: moist air, duration and temperature not stated in the entry
    source: pubchem-gaas
    where: Safety and Hazards > Stability and Reactivity > Air and Water Reactions
  - environment: Steam, acids and acid fumes
    headline: Can release arsine, and cold concentrated hydrochloric acid attacks it
    effect: PubChem says GaAs reacts with steam, acids and acid fumes to evolve arsine. It is attacked by cold concentrated hydrochloric acid and readily attacked by the halogens.
    rating: severe
    conditions:
      exposure: contact with steam or acids, concentration not stated
    source: pubchem-gaas
    where: Safety and Hazards > Stability and Reactivity > Reactivity Profile and Hazardous Reactivities
  - environment: Proton radiation in orbit
    headline: Power loss under 50 keV protons; silicon cells did not lose short-circuit current in the same study
    effect: Under 50 keV protons GaAs cells lost 30% of their short-circuit current, 10% of open-circuit voltage and about 40% of maximum power. The study notes silicon cells did not lose short-circuit current at low proton energy.
    rating: severe
    conditions:
      particle: protons, 50 keV
      cell: LPE p/n GaAs solar cells
    source: nasa-jpl-84-61
    where: Discussion of GaAs results, 50 keV proton bombardment paragraph
supply:
  - subject: Gallium
    abundance: Gallium occurs in very small concentrations in other metal ores. The average gallium content of bauxite is 50 parts per million, and most gallium is recovered from bauxite processing (USGS)
    producers:
      - country: China
        share_percent: 99
        year: 2025
    critical_lists: []
    recycling: New scrap from GaAs device manufacture was reprocessed to recover high-purity gallium at one New York facility. No old scrap was recycled (USGS 2026).
    source: usgs-gallium
    where: Gallium MCS 2026, World Low-Purity Production, Events, Trends and Issues, and Recycling sections
  - subject: Gallium arsenide wafers
    abundance: US imports of GaAs wafers were estimated at 110,000 kg gross weight in 2025, with a value of about 120 million dollars (USGS 2026)
    producers: []
    critical_lists: []
    recycling: Substantial quantities of new scrap from GaAs device manufacture were reprocessed (USGS 2026).
    source: usgs-gallium
    where: Gallium MCS 2026, Salient Statistics and Domestic Production and Use sections
  - subject: Arsenic
    abundance: Arsenic is obtained mainly from copper, gold and lead smelter flue dust, and from roasting of ores (USGS 2026). World reserves are estimated at more than 20 times world production. China supplied 95% of US arsenic metal imports in 2021 to 2024, which is an import share, not a producer share.
    producers: []
    critical_lists: []
    recycling: Arsenic metal was contained in new scrap recycled during GaAs semiconductor manufacturing (USGS 2026).
    source: usgs-arsenic
    where: Arsenic MCS 2026, Import Sources (2021 to 2024, arsenic metal) and World Resources sections
uses:
  - application: solar-arrays
    device: Triple-junction space solar cell (GaInP/GaAs/Ge)
    example: Spectrolab reports 25.1% efficiency for its triple junction and over 28.3% for its ultra-triple junction, and says the design powers GEO missions up to a possible 30 kW on a single satellite.
    source: spectrolab-nasa
    where: Introduction, paragraphs on the Triple Junction and Ultra-Triple Junction products
  - application: electronics-and-chips
    device: Power amplifier in cellular handsets
    example: USGS says silicon CMOS power amplifiers compete with GaAs power amplifiers in midtier 3G cellular handsets, which means GaAs power amplifiers are used in such handsets.
    source: usgs-gallium
    where: Substitutes section
  - application: optics-and-cameras
    device: Laser diodes, LEDs and photodetectors
    example: USGS lists GaAs wafers as the substrate for integrated circuits and optoelectronic devices, including laser diodes, LEDs, photodetectors and solar cells.
    source: usgs-gallium
    where: Domestic Production and Use section
risks:
  hazards:
    - text: 'PubChem GHS for GaAs: H350 (may cause cancer), H360F (may damage fertility) and H372 (causes damage to organs through prolonged or repeated exposure), H350 and H372 in 88.4% of company reports and H360 in 50.9%, with 6.2% (7 of 112) not meeting GHS criteria.'
      ghs:
        - H350
        - H360F
        - H372
      source: pubchem-gaas
      where: Safety and Hazards > Hazards Identification > GHS Classification (CID 14770)
    - text: When heated to decomposition, GaAs emits very toxic fumes of arsenic (NTP, 1992, as quoted by PubChem).
      ghs: []
      source: pubchem-gaas
      where: Safety and Hazards > Hazards Identification > Health Hazards
  failure_risks:
    - mode: Arsine formation
      trigger: Contact with steam, acids or acid fumes
      consequence: PubChem says GaAs can evolve the deadly poisonous gas arsine.
      severity: high
      source: pubchem-gaas
      where: Stability and Reactivity > Hazardous Reactivities and Incompatibilities
  side_effects: []
  handling:
    - text: Store under ambient temperatures in a well-ventilated area away from food and combustible materials, and protect containers from physical damage (PubChem, inorganic arsenic compounds).
      source: pubchem-gaas
      where: Handling and Storage > Storage Conditions
  mitigations:
    - text: 'Use local exhaust ventilation and, where the arsenic exposure limit may be exceeded, respiratory protection (PubChem, arsenic compounds). Limits as printed: NIOSH recommended 15-minute ceiling 0.002 mg/m3 (as As); OSHA permissible exposure 8-hour TWA 0.01 mg/m3 (as As); ACGIH TLV-TWA 0.0003 mg/m3, respirable fraction.'
      source: pubchem-gaas
      where: Exposure Control and Personal Protection > Personal Protective Equipment
media: []
documents:
  - title: PubChem compound record for gallium arsenide, CID 14770 (CAS 1303-00-0)
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/14770
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Gallium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Arsenic'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-arsenic.pdf
    year: 2026
  - title: 'JPL Publication 84-61: Radiation Effects in Silicon and Gallium Arsenide Solar Cells Using Isotropic and Normally Incident Radiation (NASA NTRS 19840026722)'
    type: report
    url: https://ntrs.nasa.gov/citations/19840026722
    year: 1984
  - title: Multijunction Solar Cell Development and Production at Spectrolab (NASA NTRS 20090022292)
    type: paper
    url: https://ntrs.nasa.gov/citations/20090022292
    year: 2018
  - title: Basic Parameters of Gallium Arsenide (GaAs), Ioffe Institute, Physical Properties of Semiconductors
    type: database
    url: http://www.ioffe.ru/SVA/NSM/Semicond/GaAs/basic.html
  - title: NIST atomic weights and isotopic compositions, standard atomic weights for Ga and As
    type: database
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Ga
  - title: EE Semi, Properties of Silicon (Si), Germanium (Ge), and Gallium Arsenide (GaAs) at 300 deg K
    type: database
    url: https://www.eesemi.com/sigegaas.htm
gaps:
  - Lattice constant, band gap, electron and hole mobility, intrinsic carrier concentration and breakdown field have no canonical name in spores/property-canon.yaml. They use snake_case names, as silicon.yaml does.
  - Direct or indirect band gap is not stated as a word in the sources read. The Ioffe band structure page lists the Gamma, L and X valleys only.
  - Critical-mineral status of gallium and arsenic was not read in this run (USGS 2025 critical minerals list not fetched).
  - Industrial process for GaAs crystal growth (Czochralski, liquid encapsulated, VGF) was not read in this run, so the recipe gives composition only.
  - Safety data sheet for GaAs powder was not read in this run; hazards come from the PubChem GHS entry and the arsenic exposure limits.
  - Proton fluence for the 50 keV loss figures and the orbit-level degradation results were not extracted from the JPL study in this run.
  - Radiation data are from a 1984 study of early LPE cells, not from current multijunction cells.
  - The Ioffe thermal conductivity (0.55 W/(cm·°C)) has no temperature stated, and the eesemi value (0.46) is at 300 K. Both are kept, with conditions.
sources:
  ioffe-basic:
    title: Ioffe Institute, Basic Parameters of Gallium Arsenide (GaAs), Basic Parameters at 300 K
    url: http://www.ioffe.ru/SVA/NSM/Semicond/GaAs/basic.html
    kind: web
    license: page content, cited as published
  ioffe-bandstr:
    title: Ioffe Institute, Band structure and carrier concentration of GaAs
    url: http://www.ioffe.ru/SVA/NSM/Semicond/GaAs/bandstr.html
    kind: web
    license: page content, cited as published
  ioffe-thermal:
    title: Ioffe Institute, Thermal properties of GaAs
    url: http://www.ioffe.ru/SVA/NSM/Semicond/GaAs/thermal.html
    kind: web
    license: page content, cited as published
  ioffe-electric:
    title: Ioffe Institute, Electrical properties of GaAs
    url: http://www.ioffe.ru/SVA/NSM/Semicond/GaAs/electric.html
    kind: web
    license: page content, cited as published
  ioffe-mechanic:
    title: Ioffe Institute, Mechanical properties, elastic constants, lattice vibrations of GaAs
    url: http://www.ioffe.ru/SVA/NSM/Semicond/GaAs/mechanic.html
    kind: web
    license: page content, cited as published
  ioffe-optic:
    title: Ioffe Institute, Optical properties of GaAs
    url: http://www.ioffe.ru/SVA/NSM/Semicond/GaAs/optic.html
    kind: web
    license: page content, cited as published
  eesemi:
    title: EE Semi, Properties of Silicon (Si), Germanium (Ge), and Gallium Arsenide (GaAs) at 300 deg K
    url: https://www.eesemi.com/sigegaas.htm
    kind: web
    license: page content, cited as published
  pubchem-gaas:
    title: PubChem, Gallium arsenide, CID 14770 (CAS 1303-00-0), Safety and Hazards and Chemical and Physical Properties
    url: https://pubchem.ncbi.nlm.nih.gov/compound/14770
    kind: database
    license: PubChem terms of use, cited as published
  usgs-gallium:
    title: 'USGS Mineral Commodity Summaries, February 2026: Gallium'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf
    kind: report
    license: public domain (USGS)
  usgs-arsenic:
    title: 'USGS Mineral Commodity Summaries, February 2026: Arsenic'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-arsenic.pdf
    kind: report
    license: public domain (USGS)
  nasa-jpl-84-61:
    title: JPL Publication 84-61, Radiation Effects in Silicon and Gallium Arsenide Solar Cells Using Isotropic and Normally Incident Radiation (Anspaugh and Downing, 1984)
    url: https://ntrs.nasa.gov/citations/19840026722
    kind: report
    license: NASA NTRS, public use
  spectrolab-nasa:
    title: Fetzer et al., Multijunction Solar Cell Development and Production at Spectrolab (NASA NTRS 20090022292)
    url: https://ntrs.nasa.gov/citations/20090022292
    kind: paper
    license: NASA NTRS, public use
  nist-atomic-weights:
    title: NIST, Atomic Weights and Isotopic Compositions for Gallium and Arsenic (standard atomic weights)
    url: https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=Ga
    kind: database
    license: public domain (NIST)
license: CC-BY-4.0
updated: '2026-10-19'
review:
  status: draft
  method: assistant
  checked_values: 34
  note: Written by an AI assistant on 2026-10-19 from pages fetched in this run. Not yet re-checked against the cited sources.