{ "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.\n", "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)", "designations": [], "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, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "density", "label": "Density (mechanical properties table)", "value": 5.317, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "density", "label": "Density (table at 300 K)", "value": 5.32, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "lattice_constant", "label": "Lattice constant", "value": 5.65325, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "lattice_constant", "label": "Lattice constant (table at 300 K)", "value": 5.6533, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point", "value": 1240, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point (table at 300 K)", "value": 1238, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "bandgap", "label": "Energy band gap at 300 K", "value": 1.424, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "bandgap", "label": "Energy band gap at 300 K (table)", "value": 1.424, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "electron_mobility", "label": "Electron drift mobility", "value": 8500, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "electron_mobility", "label": "Electron mobility (upper limit for weakly doped material)", "value": 8500, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "hole_mobility", "label": "Hole drift mobility", "value": 400, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity", "value": 0.46, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity (no temperature stated)", "value": 0.55, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "specific_heat", "label": "Specific heat (table at 300 K)", "value": 0.35, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "specific_heat", "label": "Specific heat (no temperature stated)", "value": 0.33, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "cte", "label": "Linear thermal expansion (table at 300 K)", "value": 0.00000686, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "cte", "label": "Linear thermal expansion (no temperature stated)", "value": 0.00000573, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "dielectric_constant", "label": "Dielectric constant (static)", "value": 12.9, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "dielectric_constant", "label": "Dielectric constant (table at 300 K)", "value": 13.1, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "bulk_modulus", "label": "Bulk modulus", "value": 753000000000, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "poissons_ratio", "label": "Poisson ratio", "value": 0.31, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "intrinsic_carrier_concentration", "label": "Intrinsic carrier concentration (table at 300 K)", "value": 1790000, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "intrinsic_carrier_concentration", "label": "Intrinsic carrier concentration (band structure page)", "value": 2100000, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "electrical_resistivity", "label": "Intrinsic resistivity", "value": 330000000, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "refractive_index", "label": "Infrared refractive index", "value": 3.3, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "electron_affinity", "label": "Electron affinity", "value": 4.07, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "breakdown_field", "label": "Breakdown field", "value": 400000, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "efficiency_am0", "label": "Efficiency, GaInP/GaAs/Ge ultra-triple-junction (max power, AM0)", "value": 28.3, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "efficiency_am0", "label": "Efficiency, GaInP/GaAs/Ge triple junction (on orbit since 2001, beginning of life)", "value": 25.1, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "efficiency_am0", "label": "Efficiency, dual-junction GaInP/GaAs (first commercial satellite, 1997, beginning of life)", "value": 21.5, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "maximum_power_loss", "label": "Maximum power loss, GaAs cells under 50 keV protons", "value": 40, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "short_circuit_current_loss", "label": "Short-circuit current loss, GaAs cells under 50 keV protons", "value": 30, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "damage_coefficient_ratio", "label": "Maximum-power damage coefficient, GaAs relative to silicon, 150 keV protons", "value": 30, "bound": "exact", "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", "source_detail": { "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" } } ], "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" } ], "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" } ] }, "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" } ], "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).", "substitutes": [], "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).", "substitutes": [], "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).", "substitutes": [], "source": "usgs-arsenic", "where": "Arsenic MCS 2026, Import Sources (2021 to 2024, arsenic metal) and World Resources sections" } ], "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." ], "story": { "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", "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.", "benchmark": "electron_mobility", "scope": "material", "value": "8500" }, { "label": "Absorb and emit at a wide band gap", "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.", "benchmark": "bandgap", "scope": "material", "value": "1.424" }, { "label": "Hold up in orbit, with a cost", "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.", "benchmark": "damage_coefficient_ratio", "scope": "material", "value": "30" } ], "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": [ { "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", "scope": "material" } ], "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.", "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.\n", "parts": [ { "name": "Gallium", "symbol": "Ga", "role": "The group III element. Gallium supplies the metal sites of the zinc-blende lattice, and its supply is concentrated in China.", "atoms": 1, "atomic_weight": 69.723 }, { "name": "Arsenic", "symbol": "As", "role": "The group V element. Arsenic occupies the other sublattice, and it is the main source of the substance's toxicity.", "atoms": 1, "atomic_weight": 74.921595 } ] }, "risk_groups": [ { "title": "For people", "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)." } ], "level": 2, "verdict": "Hazardous, carcinogenic" }, { "title": "If it fails", "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." } ], "level": 1, "verdict": "Dust and acid release arsine" }, { "title": "Handling and storage", "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." } ], "level": 1, "verdict": "Keep away from acids and steam" } ] }, "updated": "2026-10-19", "review": { "status": "draft", "method": "assistant", "checked_values": 34, "unreachable": 0, "caveats": 0, "note": "Written by an AI assistant on 2026-10-19 from pages fetched in this run. Not yet re-checked against the cited sources." }, "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", "url": "https://spacemushroom.com/profiles/gallium-arsenide/" }