{ "spore": "profile", "id": "aluminium-gallium-nitride", "spore_version": "0.2", "family": "nitride-semiconductors", "name": "Aluminium gallium nitride", "abbreviation": "AlGaN", "role": "wide-bandgap semiconductor alloy", "category": "semiconductors", "type": "gan", "summary": "Aluminium gallium nitride (AlGaN) is an alloy of aluminium nitride and gallium nitride, written AlxGa1-xN. NASA gives the direct bandgaps of GaN and AlN as 3.4 eV and 6.2 eV, so the aluminium fraction x sets a bandgap anywhere between those two values. A 2006 trade article reports a back-illuminated AlGaN array from BAE Systems with a 280 nm solar-blind cut-off, using an Al0.47Ga0.53N absorber. NASA reports that AlGaN detectors can be designed to reject solar radiation about 1000 times better than silicon detectors at a 325 nm cut-off. No density or melting point for the alloy was found in the sources read for this profile. Calculated alloy values at x = 0.5 are listed: lattice constants (DFT), a first-principles thermal conductivity, and a bulk modulus from a machine-learning potential. These are calculations, not measurements.\n", "best_for": "Ultraviolet detectors that must ignore sunlight, such as solar-blind work below 280 nm (BAE Systems) and planetary UV instruments (NASA Goddard)", "weakest_at": "Few material constants for the alloy were found. The numbers here are mostly device results, and the cut-off figures differ between sources (see gaps)", "identity": { "formula": "AlxGa1-xN, an alloy of aluminium nitride (AlN) and gallium nitride (GaN); x is the aluminium fraction", "designations": [], "source": "wiki-algan", "where": "Lead section (formula AlxGa1-xN; alloy of AlN and GaN)" }, "tags": { "environments": [], "stresses": [], "applications": [ "optics-and-cameras" ] }, "properties": [ { "benchmark": "bandgap", "label": "Direct bandgap, GaN to AlN end members (alloy range)", "value": 3.4, "value_high": 6.2, "bound": "range", "unit": "eV", "scope": "material", "conditions": { "composition": "AlxGa1-xN from x = 0 (GaN) to x = 1 (AlN)", "temperature": "not stated in the abstract", "basis": "end-member values from the abstract; the bandgap at intermediate x is not given in this source" }, "method": "Direct bandgaps printed in the NASA abstract for three nitrides, read as InN, GaN and AlN in that order; the 3.4 eV and 6.2 eV values are the GaN and AlN entries", "status": "ground", "source": "ntrs-2012", "where": "Abstract, sentence giving direct bandgaps 0.8, 3.4 and 6.2 eV, respectively", "source_detail": { "title": "GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions", "id": "NTRS 20120016988; GSFC.CPR.6772.2012; IPM-2012 (October 10, 2012)", "url": "https://ntrs.nasa.gov/citations/20120016988", "year": 2012, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "cutoff_wavelength", "label": "Tunable detection range of AlGaN alloys", "value": 200, "value_high": 365, "bound": "range", "unit": "nm", "scope": "material", "conditions": { "basis": "tunable direct-bandgap range quoted for AlGaN alloys", "composition": "AlGaN across the alloy range" }, "method": "Range printed in a 2006 trade article on AlGaN filter-free detection; the NASA abstract gives 200 nm for AlN and 365 nm for GaN as the matching ends", "status": "ground", "source": "compoundsemi-2006", "where": "Article text on the tunable direct bandgap (section not labelled in the fetched text)", "source_detail": { "title": "AlGaN provides filter-free detection (Compound Semiconductor, article 84128)", "id": "Compound Semiconductor, published 27 June 2006", "url": "https://compoundsemiconductor.net/article/84128/AlGaN_provides_filter-free_detection", "year": 2006, "kind": "web", "license": "trade article, cited not reproduced" } }, { "benchmark": "cutoff_wavelength", "label": "Solar-blind cut-off of the AlGaN absorber", "value": 280, "bound": "exact", "unit": "nm", "scope": "material", "conditions": { "absorber": "Al0.47Ga0.53N", "device": "back-illuminated AlGaN hybrid focal-plane array developed at BAE Systems, Lexington, MA", "operation": "solar-blind, below 280 nm" }, "method": "Cut-off wavelength printed in the article for the absorber layer", "status": "ground", "note": "The NASA abstract gives 325 nm for its AlGaN design (see the 325 nm row below). Both figures are printed; this profile does not choose between them.", "source": "compoundsemi-2006", "where": "Article text on the Al0.47Ga0.53N absorber and solar-blind operation below 280 nm", "source_detail": { "title": "AlGaN provides filter-free detection (Compound Semiconductor, article 84128)", "id": "Compound Semiconductor, published 27 June 2006", "url": "https://compoundsemiconductor.net/article/84128/AlGaN_provides_filter-free_detection", "year": 2006, "kind": "web", "license": "trade article, cited not reproduced" } }, { "benchmark": "cut_on_wavelength", "label": "Short-wavelength edge of the photosensitivity band", "value": 260, "bound": "exact", "unit": "nm", "scope": "material", "conditions": { "device": "back-illuminated AlGaN hybrid focal-plane array (BAE Systems)", "band": "260 to 280 nm photosensitivity" }, "method": "Cut-on wavelength printed in the article", "status": "ground", "source": "compoundsemi-2006", "where": "Article text on the 260 to 280 nm photosensitivity band", "source_detail": { "title": "AlGaN provides filter-free detection (Compound Semiconductor, article 84128)", "id": "Compound Semiconductor, published 27 June 2006", "url": "https://compoundsemiconductor.net/article/84128/AlGaN_provides_filter-free_detection", "year": 2006, "kind": "web", "license": "trade article, cited not reproduced" } }, { "benchmark": "quantum_efficiency_peak", "label": "Peak quantum efficiency at zero bias", "value": 48, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "bias": "zero bias", "device": "AlGaN photodiode described in the article", "wavelength": "not stated in the fetched article text" }, "method": "Peak quantum efficiency printed in the article's detector performance paragraph", "status": "ground", "source": "compoundsemi-2006", "where": "Article text, detector performance paragraph (48% peak quantum efficiency at zero bias)", "source_detail": { "title": "AlGaN provides filter-free detection (Compound Semiconductor, article 84128)", "id": "Compound Semiconductor, published 27 June 2006", "url": "https://compoundsemiconductor.net/article/84128/AlGaN_provides_filter-free_detection", "year": 2006, "kind": "web", "license": "trade article, cited not reproduced" } }, { "benchmark": "quantum_efficiency", "label": "Quantum efficiency at 270 nm", "value": 50, "bound": "lower", "unit": "%", "scope": "material", "conditions": { "wavelength": "270 nm", "device": "solar-blind AlGaN array described in the article" }, "method": "Printed as more than 50% at 270 nm in the article", "status": "ground", "source": "compoundsemi-2006", "where": "Article text, detector performance paragraph (quantum efficiency of more than 50% at 270 nm)", "source_detail": { "title": "AlGaN provides filter-free detection (Compound Semiconductor, article 84128)", "id": "Compound Semiconductor, published 27 June 2006", "url": "https://compoundsemiconductor.net/article/84128/AlGaN_provides_filter-free_detection", "year": 2006, "kind": "web", "license": "trade article, cited not reproduced" } }, { "benchmark": "quantum_efficiency", "label": "Quantum efficiency without reflection loss", "value": 52.3, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "device": "UT diode described in the article", "basis": "figure the authors state would apply with no reflection loss" }, "method": "Corrected figure stated by the article's authors; not a direct measurement in the source", "status": "calculated", "source": "compoundsemi-2006", "where": "Article text, quantum efficiency paragraph (the UT diode quantum efficiency would have been 52.3%)", "source_detail": { "title": "AlGaN provides filter-free detection (Compound Semiconductor, article 84128)", "id": "Compound Semiconductor, published 27 June 2006", "url": "https://compoundsemiconductor.net/article/84128/AlGaN_provides_filter-free_detection", "year": 2006, "kind": "web", "license": "trade article, cited not reproduced" } }, { "benchmark": "solar_rejection_ratio", "label": "Solar radiation rejection compared with silicon (NASA Tech Briefs)", "value": 1000, "bound": "exact", "unit": "x", "scope": "material", "conditions": { "reference": "silicon-based detectors", "basis": "stated for AlGaN UV detectors in the NASA Tech Briefs article" }, "method": "Figure printed in the NASA Goddard Tech Briefs article dated October 1, 2010", "status": "ground", "source": "techbriefs-gsc15673", "where": "Article body, AlGaN solar radiation rejection compared with silicon", "source_detail": { "title": "NASA Tech Briefs article, reference GSC-15673-1 (AlGaN solar-blind UV detector)", "id": "GSC-15673-1; NASA Tech Briefs Vol. 34 No. 10 (October 1, 2010)", "url": "https://www.techbriefs.com/component/content/article/8640-gsc-15673-1", "year": 2010, "kind": "web", "license": "public domain (NASA text)" } }, { "benchmark": "cutoff_wavelength", "label": "Cut-off wavelength of an AlGaN UV detector design (planetary)", "value": 325, "bound": "exact", "unit": "nm", "scope": "material", "conditions": { "basis": "cut-off named in the same sentence as the 1000x rejection figure", "reference": "silicon-based detectors" }, "method": "Cut-off printed in the NASA abstract", "status": "ground", "note": "Conflicts with the 280 nm solar-blind cut-off printed in the 2006 article. Both are kept; no source reconciles them.", "source": "ntrs-2012", "where": "Abstract, sentence on AlGaN UV rejection compared with Si-based detectors", "source_detail": { "title": "GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions", "id": "NTRS 20120016988; GSFC.CPR.6772.2012; IPM-2012 (October 10, 2012)", "url": "https://ntrs.nasa.gov/citations/20120016988", "year": 2012, "kind": "report", "license": "public domain (NASA)" } }, { "benchmark": "responsivity", "label": "Current responsivity at 360 nm, 0 V", "value": 0.13, "bound": "exact", "unit": "A/W", "scope": "material", "conditions": { "wavelength": "360 nm", "bias": "0 V", "device": "AlGaN UV PIN photodiode as described in the NASA Tech Briefs article" }, "method": "Figure printed in the NASA Tech Briefs article", "status": "ground", "note": "The same article gives a 365 nm long-wavelength cut-off for this device, which matches the GaN value in the NASA abstract. The composition of this device is not stated, so it is not the 280 nm absorber.", "source": "techbriefs-gsc15673", "where": "Article body, performance figures for the AlGaN photodiode", "source_detail": { "title": "NASA Tech Briefs article, reference GSC-15673-1 (AlGaN solar-blind UV detector)", "id": "GSC-15673-1; NASA Tech Briefs Vol. 34 No. 10 (October 1, 2010)", "url": "https://www.techbriefs.com/component/content/article/8640-gsc-15673-1", "year": 2010, "kind": "web", "license": "public domain (NASA text)" } }, { "benchmark": "quantum_efficiency_peak", "label": "Peak quantum efficiency at 360 nm, -0.5 V", "value": 50, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "wavelength": "360 nm", "bias": "-0.5 V", "device": "same AlGaN photodiode as the 0.13 A/W responsivity row" }, "method": "Figure printed in the NASA Tech Briefs article", "status": "ground", "note": "Same device caveat as the responsivity row: its cut-off is printed as 365 nm.", "source": "techbriefs-gsc15673", "where": "Article body, performance figures for the AlGaN photodiode", "source_detail": { "title": "NASA Tech Briefs article, reference GSC-15673-1 (AlGaN solar-blind UV detector)", "id": "GSC-15673-1; NASA Tech Briefs Vol. 34 No. 10 (October 1, 2010)", "url": "https://www.techbriefs.com/component/content/article/8640-gsc-15673-1", "year": 2010, "kind": "web", "license": "public domain (NASA text)" } }, { "benchmark": "lattice_constant_a", "label": "Lattice constant a, Al0.50Ga0.50N (DFT)", "value": 3.1719, "bound": "exact", "unit": "Å", "scope": "material", "conditions": { "composition": "Al0.50Ga0.50N (x = 0.5)", "structure": "wurtzite", "basis": "density functional theory calculation in the paper, listed as Present Work" }, "method": "DFT with the generalized gradient approximation (GGA) on the wurtzite cell, as stated in the paper's abstract", "status": "calculated", "source": "arxiv-lattice-0811", "where": "Table I, Al0.50 Ga0.50 N row, a column", "source_detail": { "title": "Ab initio calculation of structural and electronic properties of AlxGa1-xN and InxGa1-xN alloys", "id": "arXiv:0811.0380; E. López-Apreza, J. Arriaga and D. Olguín (2008)", "url": "https://arxiv.org/pdf/0811.0380", "year": 2008, "kind": "paper", "license": "arXiv preprint" } }, { "benchmark": "lattice_constant_c", "label": "Lattice constant c, Al0.50Ga0.50N (DFT)", "value": 5.1012, "bound": "exact", "unit": "Å", "scope": "material", "conditions": { "composition": "Al0.50Ga0.50N (x = 0.5)", "structure": "wurtzite", "basis": "density functional theory calculation in the paper, listed as Present Work" }, "method": "DFT with the generalized gradient approximation (GGA) on the wurtzite cell, as stated in the paper's abstract", "status": "calculated", "source": "arxiv-lattice-0811", "where": "Table I, Al0.50 Ga0.50 N row, c column", "source_detail": { "title": "Ab initio calculation of structural and electronic properties of AlxGa1-xN and InxGa1-xN alloys", "id": "arXiv:0811.0380; E. López-Apreza, J. Arriaga and D. Olguín (2008)", "url": "https://arxiv.org/pdf/0811.0380", "year": 2008, "kind": "paper", "license": "arXiv preprint" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity along [100], Al0.5Ga0.5N (first-principles)", "value": 186.74, "bound": "exact", "unit": "W/(m·K)", "scope": "material", "conditions": { "composition": "Al0.5Ga0.5N", "direction": "[100]", "temperature": "300 K" }, "method": "First-principles calculation of anisotropic thermal conductivity, printed in the paper's abstract", "status": "calculated", "source": "mpm-thermal-2022", "where": "Abstract, Al0.5Ga0.5N row of the thermal conductivity table, [100] column", "source_detail": { "title": "First-principles study of anisotropic thermal conductivity of GaN, AlN, and Al0.5Ga0.5N", "id": "Materials Physics and Mechanics 49(1), pp. 97-107; D. Hvazdouski, M.S. Baranava and V.R. Stempitsky (2022)", "url": "https://mpm.spbstu.ru/article/2022.89.7/", "year": 2022, "kind": "paper", "license": "not checked" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity along [001], Al0.5Ga0.5N (first-principles)", "value": 165.24, "bound": "exact", "unit": "W/(m·K)", "scope": "material", "conditions": { "composition": "Al0.5Ga0.5N", "direction": "[001]", "temperature": "300 K" }, "method": "First-principles calculation of anisotropic thermal conductivity, printed in the paper's abstract", "status": "calculated", "source": "mpm-thermal-2022", "where": "Abstract, Al0.5Ga0.5N row of the thermal conductivity table, [001] column", "source_detail": { "title": "First-principles study of anisotropic thermal conductivity of GaN, AlN, and Al0.5Ga0.5N", "id": "Materials Physics and Mechanics 49(1), pp. 97-107; D. Hvazdouski, M.S. Baranava and V.R. Stempitsky (2022)", "url": "https://mpm.spbstu.ru/article/2022.89.7/", "year": 2022, "kind": "paper", "license": "not checked" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity along [111], Al0.5Ga0.5N (first-principles)", "value": 177.62, "bound": "exact", "unit": "W/(m·K)", "scope": "material", "conditions": { "composition": "Al0.5Ga0.5N", "direction": "[111]", "temperature": "300 K" }, "method": "First-principles calculation of anisotropic thermal conductivity, printed in the paper's abstract", "status": "calculated", "source": "mpm-thermal-2022", "where": "Abstract, Al0.5Ga0.5N row of the thermal conductivity table, [111] column", "source_detail": { "title": "First-principles study of anisotropic thermal conductivity of GaN, AlN, and Al0.5Ga0.5N", "id": "Materials Physics and Mechanics 49(1), pp. 97-107; D. Hvazdouski, M.S. Baranava and V.R. Stempitsky (2022)", "url": "https://mpm.spbstu.ru/article/2022.89.7/", "year": 2022, "kind": "paper", "license": "not checked" } }, { "benchmark": "bulk_modulus", "label": "Bulk modulus, Al0.5Ga0.5N (machine-learning potential)", "value": 204, "bound": "exact", "unit": "GPa", "scope": "material", "conditions": { "composition": "Al0.5Ga0.5N (x = 0.5), wurtzite", "basis": "prediction from a machine-learning interatomic potential, labelled This work in Table I" }, "method": "Elastic constants and bulk modulus B from the machine-learning potential at the ground state, as printed in the paper", "status": "calculated", "source": "arxiv-elastic-2510", "where": "Table I, Al0.5 Ga0.5 N row, B column", "source_detail": { "title": "Evaluation of Structural Properties and Defect Energetics in AlxGa1-xN Alloys", "id": "arXiv:2510.25912; F. Reza, B. Chen and M. Jin (Pennsylvania State University, 2025)", "url": "https://arxiv.org/pdf/2510.25912", "year": 2025, "kind": "paper", "license": "arXiv preprint" } }, { "benchmark": "frenkel_pair_formation_energy", "label": "Lowest nitrogen Frenkel pair formation energy, AlGaN with 25% Al", "value": 6.57, "bound": "exact", "unit": "eV", "scope": "material", "conditions": { "composition": "25% Al (AlxGa1-xN, x = 0.25)", "defect": "nitrogen Frenkel pair (a vacancy plus an interstitial), lowest-energy configuration in the energy histogram" }, "method": "Machine-learning interatomic potential calculation, as stated in the paper's text; not an irradiation experiment", "status": "calculated", "source": "arxiv-elastic-2510", "where": "Section B (Frenkel Pair Formation Energy), paragraph on the 25% Al energy histogram", "source_detail": { "title": "Evaluation of Structural Properties and Defect Energetics in AlxGa1-xN Alloys", "id": "arXiv:2510.25912; F. Reza, B. Chen and M. Jin (Pennsylvania State University, 2025)", "url": "https://arxiv.org/pdf/2510.25912", "year": 2025, "kind": "paper", "license": "arXiv preprint" } } ], "corrosion": [], "risks": { "hazards": [ { "text": "PubChem GHS for gallium nitride, the GaN end member (not AlGaN itself): H317, May cause an allergic skin reaction, with signal word Warning, reported in 97.8% of aggregated company notifications. 2.2% of reports say the chemical does not meet GHS hazard criteria.", "ghs": [ "H317" ], "source": "pubchem-gan", "where": "Safety and Hazards, Hazards Identification, GHS Classification (CID 117559)" } ], "failure_risks": [ { "mode": "Nitrogen Frenkel pair defects in AlGaN under radiation or high temperature", "trigger": "Irradiation or high-temperature processing (calculated only; the paper does not test irradiation)", "consequence": "The paper calculates that low-energy nitrogen Frenkel pairs exist in AlGaN, with the lowest at 6.57 eV at 25% Al, and states that under irradiation or high-temperature processing these configurations may form preferentially and dominate the early defect population.", "source": "arxiv-elastic-2510", "where": "Section B, Frenkel pair formation energy, and the implications paragraph" } ], "side_effects": [], "handling": [], "mitigations": [] }, "uses": [ { "application": "optics-and-cameras", "device": "Back-illuminated solar-blind UV focal-plane array (256 x 256 pixels)", "example": "The 2006 article describes BAE Systems' first solar-blind 256 x 256 AlGaN back-illuminated hybrid UV focal-plane arrays, with 30 um x 30 um unit cells and photosensitivity in the 260 to 280 nm band.", "source": "compoundsemi-2006", "where": "Article text on the 256 x 256 array and unit cells" }, { "application": "optics-and-cameras", "device": "UV detector for planetary missions", "example": "NASA Goddard's abstract, titled for next-generation ultraviolet planetary missions, says AlGaN detectors can be designed to give 1000x solar radiation rejection at a 325 nm cut-off, compared with Si-based detectors.", "source": "ntrs-2012", "where": "Title and abstract" }, { "application": "optics-and-cameras", "device": "UV sensing instruments for plume, flame, lidar and bio-agent work", "example": "The NASA Tech Briefs article lists AlGaN UV detector uses as plume measurements, flame sensing, UV lidar, biological agent detection, and airborne particulate size and velocity measurement.", "source": "techbriefs-gsc15673", "where": "Article body, applications paragraph" } ], "supply": [ { "subject": "Gallium", "producers": [ { "country": "China", "share_percent": 99, "year": 2025 } ], "critical_lists": [ { "list": "USGS 2025 List of Critical Minerals (entry: Gallium, used in semiconductors)", "listed": true }, { "list": "EU critical raw materials list (Regulation (EU) 2024/1252, entry: Gallium)", "listed": true } ], "recycling": "USGS: old scrap recovery is none. Substantial new scrap from GaAs device manufacture was reprocessed to high-purity gallium at one New York facility.", "substitutes": [ "USGS: in many defense-related applications no effective substitutes exist for GaAs and GaN." ], "source": "usgs-mcs2026-gallium", "where": "Events, Trends, and Issues (China accounted for 99% of worldwide primary low-purity gallium production); Recycling; Substitutes; Salient Statistics table (net import reliance 100 in every year listed). The 99% is for primary low-purity gallium, not for refined gallium used in AlGaN." }, { "subject": "Aluminium (USGS spelling: aluminum)", "producers": [ { "country": "China", "share_percent": 60.8, "year": 2025 }, { "country": "India", "share_percent": 5.7, "year": 2025 }, { "country": "Russia", "share_percent": 5.3, "year": 2025 }, { "country": "Canada", "share_percent": 4.5, "year": 2025 } ], "critical_lists": [ { "list": "USGS 2025 List of Critical Minerals (entry: Aluminum, used in almost all sectors of the economy)", "listed": true }, { "list": "EU critical raw materials list (aluminium merged into the Bauxite entry, per the European Commission page)", "listed": true } ], "recycling": "USGS: about 3.6 million tons of aluminum were recovered from purchased scrap in the United States in 2025.", "substitutes": [], "source": "usgs-mcs2026-aluminum", "where": "World smelter production table, 2025e (shares calculated by Space Mushroom from China 45,000, India 4,200, Russia 3,900 and Canada 3,300 against the printed world total of 74,000, rounded); Recycling. Aluminium is the feedstock for the aluminium part of the alloy." } ], "media": [], "documents": [ { "title": "NASA NTRS 20120016988: GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions", "type": "report", "url": "https://ntrs.nasa.gov/citations/20120016988", "year": 2012 }, { "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: Aluminum", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf", "year": 2026 }, { "title": "NASA Tech Briefs article, reference GSC-15673-1", "type": "report", "url": "https://www.techbriefs.com/component/content/article/8640-gsc-15673-1", "year": 2010 }, { "title": "arXiv 0811.0380: Ab initio calculation of structural and electronic properties of AlxGa1-xN and InxGa1-xN alloys", "type": "paper", "url": "https://arxiv.org/pdf/0811.0380", "year": 2008 }, { "title": "arXiv 2510.25912: Evaluation of Structural Properties and Defect Energetics in AlxGa1-xN Alloys", "type": "paper", "url": "https://arxiv.org/pdf/2510.25912", "year": 2025 }, { "title": "Materials Physics and Mechanics 49(1): First-principles study of anisotropic thermal conductivity of GaN, AlN, and Al0.5Ga0.5N", "type": "paper", "url": "https://mpm.spbstu.ru/article/2022.89.7/", "year": 2022 }, { "title": "PubChem CID 117559: Gallium nitride, GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Gallium-nitride", "year": 2026 } ], "gaps": [ "Density, melting or decomposition temperature, electron mobility and breakdown field for AlGaN were not found in any source read in this run. The lattice constants, thermal conductivity and bulk modulus in the properties list are calculated values at x = 0.5, not measurements. The arXiv 0811.0380 table also gives lattice constants at x = 0.25 and 0.75, which are not added.", "The Ioffe Institute basic-parameter page for AlGaN could not be opened in this run (self-signed certificate error), so its band-gap bowing and thermal values are not used. The Springer and Balandin group AlGaN pages and a DOAJ record for a 270 nm AlGaN LED irradiation paper could not be opened either (redirect, DNS failure and a Cloudflare block).", "No safety data sheet or GHS entry for AlGaN itself was found. The hazard entry is for the GaN end member from PubChem. The Wikipedia safety note (toxicology not fully studied; dust irritates skin, eyes and lungs) was not used as a source because the brief limits Wikipedia to composition and history. A supplier SDS for AlGaN wafers or powder is needed.", "No corrosion, oxidation, ageing or humidity test for AlGaN was read, so the corrosion list is empty.", "The one failure entry is a calculated defect energy from a machine-learning potential. No irradiation test or device-level failure data for AlGaN was read. The source gives no severity, so the failure entry has no severity field.", "Lattice constants a and c and the frenkel_pair_formation_energy benchmark are short snake_case names not in spores/property-canon.yaml. Elastic constants C11, C12, C13, C33 and C44 for Al0.5Ga0.5N (2510.25912 Table I) are not added, only the bulk modulus B.", "AlGaN/GaN high-electron-mobility transistor use is named only in Wikipedia. No HEMT property (mobility, carrier density, power or frequency) was read.", "The 280 nm solar-blind cut-off (2006 article) and the 325 nm cut-off (NASA abstract) are both printed. No source reconciles them.", "The 48% peak quantum efficiency is printed without a wavelength in the fetched article text.", "The NASA Tech Briefs device is called AlGaN but has a 365 nm cut-off, and its composition is not stated. Its responsivity and quantum efficiency rows are kept with that caveat.", "No atomic weight for aluminium, gallium or nitrogen was read in a fetched source, so the recipe parts carry no atomic weights.", "No standard designation (UNS, EN, CAS) exists for the alloy in any source read; AlGaN is a composition family, not one grade.", "Crustal abundance of gallium and aluminium was not read in this run.", "Benchmark names cutoff_wavelength, cut_on_wavelength, quantum_efficiency, quantum_efficiency_peak, responsivity and solar_rejection_ratio are short snake_case names. None is in spores/property-canon.yaml, and bandgap is used as in the GaN profile.", "The 99% gallium share is a USGS statement about primary low-purity production. The aluminium shares are calculated by Space Mushroom from smelter production, not taken from a printed share. - \"The NASA abstract's 1000x rejection figure is read from the fetched summary. The PDF text layer prints it as I OOOx (OCR), so the value check could not match it and the figure has no verified property row. The NASA Tech Briefs row with the same figure could not be read by the value check either.\"" ], "story": { "why": "Aluminium gallium nitride (AlGaN) is a semiconductor that can be tuned across the ultraviolet. NASA gives direct bandgaps of 3.4 eV for GaN and 6.2 eV for AlN, and the aluminium fraction sets the value in between. A detector that absorbs only below a chosen wavelength can ignore the visible and near-visible light of the Sun. NASA Goddard works on this family of detectors for next-generation ultraviolet planetary missions.", "uses": [ { "where": "Solar-blind ultraviolet focal-plane arrays", "line": "A 2006 article describes BAE Systems' 256 x 256 back-illuminated AlGaN hybrid arrays, with an absorber that cuts off at 280 nm and a photosensitivity band of 260 to 280 nm." }, { "where": "Planetary ultraviolet detectors", "line": "NASA's abstract says AlGaN detectors can be designed to reject solar radiation 1000 times better than silicon detectors at a 325 nm cut-off." }, { "where": "UV sensing instruments", "line": "A NASA Tech Briefs article lists plume measurements, flame sensing, UV lidar, biological agent detection and airborne particle sizing as uses of AlGaN UV detectors." } ], "can_do": [ { "label": "Bandgap tuning", "line": "The NASA abstract gives direct bandgaps of 3.4 eV for GaN and 6.2 eV for AlN, the two ends of the alloy range. The bandgap of the alloy at a given aluminium fraction is not printed in the sources read.", "benchmark": "bandgap", "scope": "material", "value": "3.4 to 6.2 eV" }, { "label": "Solar-blind cut-off", "line": "The 2006 article says an Al0.47Ga0.53N absorber gives a 280 nm cut-off, and that the array operates below 280 nm, the solar-blind band.", "benchmark": "cutoff_wavelength", "scope": "material", "value": "280 nm" }, { "label": "Solar rejection", "line": "NASA gives 1000 times better solar rejection than silicon detectors at a 325 nm cut-off, and a NASA Tech Briefs article repeats the 1000x figure.", "benchmark": "solar_rejection_ratio", "scope": "material", "value": "1000x" }, { "label": "Quantum efficiency", "line": "The 2006 article gives a 48% peak quantum efficiency at zero bias for an AlGaN photodiode, and more than 50% at 270 nm.", "benchmark": "quantum_efficiency_peak", "scope": "material", "value": "48%" } ], "compare": "AlGaN covers a tunable part of the ultraviolet that GaN alone cannot, because the aluminium fraction moves the bandgap from the 365 nm GaN cut-off down toward the 200 nm AlN end (NASA abstract). Silicon is the reference for solar rejection: NASA gives 1000 times better rejection for AlGaN than silicon at a 325 nm cut-off. The sources read give no density or mobility for the alloy. The thermal conductivity and lattice values at x = 0.5 are first-principles calculations, so they are not ranked against measured values for other materials.", "compare_rows": [ { "label": "Bandgap across the alloy range", "benchmark": "bandgap", "scope": "material" }, { "label": "Solar-blind cut-off", "benchmark": "cutoff_wavelength", "scope": "material" }, { "label": "Quantum efficiency at peak", "benchmark": "quantum_efficiency_peak", "scope": "material" } ], "handling": [ "No handling data for AlGaN were found in the sources read this run. Use the supplier safety data sheet for the wafer or powder you buy.", "Keep the wafer or powder dry and closed until use, and avoid dust, pending a product SDS." ], "good_for": [ "Solar-blind ultraviolet detection, where the 2006 article reports operation below 280 nm.", "Planetary ultraviolet instruments, where NASA reports 1000 times better solar rejection than silicon." ], "watch_out": [ "Sources disagree on the cut-off: 280 nm for the 2006 BAE Systems absorber and 325 nm for the NASA design. Both are printed.", "The NASA Tech Briefs photodiode has a 365 nm cut-off, which matches GaN, so its numbers are for a different design.", "No density, melting point, mobility or breakdown field for the alloy was found in any source read this run. The thermal conductivity and bulk modulus rows are first-principles or machine-learning calculations, not measurements.", "The one failure entry is calculated, not tested: a nitrogen Frenkel pair energy from the machine-learning study, with no irradiation test on AlGaN read." ], "verdict": "AlGaN is a tunable ultraviolet semiconductor whose bandgap range is documented at its two ends, 3.4 eV for GaN and 6.2 eV for AlN. The device numbers are results from detectors, and the alloy constants are calculated at x = 0.5, so the material data are still thin, with no measured density, melting point or mobility for the alloy found yet.", "recipe": { "line": "AlGaN is an alloy of aluminium nitride (AlN) and gallium nitride (GaN), written AlxGa1-xN. The aluminium fraction x sets the bandgap. The 2006 article says the detector layers were grown on 2 inch c-plane sapphire substrates.", "parts": [ { "name": "Aluminium", "symbol": "Al", "role": "Sets the bandgap. The NASA abstract gives 6.2 eV for pure AlN, the wide end of the alloy range." }, { "name": "Gallium", "symbol": "Ga", "role": "Sets the bandgap. The NASA abstract gives 3.4 eV for pure GaN, the narrow end of the alloy range." }, { "name": "Nitrogen", "symbol": "N", "role": "Bonds to the metal atoms in the nitride lattice. The sources read give no further detail." } ] }, "risk_groups": [ { "title": "For people", "lead": "No safety data sheet or GHS entry for AlGaN itself was read. PubChem's GHS entry for the GaN end member gives H317, a skin sensitiser warning.", "points": [ { "label": "Dust", "line": "Handle wafers and powder with care until a supplier safety data sheet for the specific product has been checked." }, { "label": "Skin contact", "line": "PubChem's aggregated GHS entry for gallium nitride lists H317, may cause an allergic skin reaction, and signal word Warning." } ], "verdict": "GaN end member carries H317 (may cause an allergic skin…" } ] }, "updated": "2026-11-01", "review": { "status": "draft", "method": "assistant", "checked_values": 18, "unreachable": 4, "caveats": 3, "note": "Written by an AI assistant on 2026-11-01 from the NASA, trade, alloy-calculation and USGS pages, and deepened the same day with arXiv tables, an MPM first-principles paper and PubChem GHS data. Values are copied as printed. The Ioffe AlGaN page, the Springer and Balandin pages and a DOAJ record could not be opened. The NASA full text was read from a fetch summary." }, "sources": { "ntrs-2012": { "title": "GaN-Based Detector Enabling Technology for Next Generation Ultraviolet Planetary Missions", "id": "NTRS 20120016988; GSFC.CPR.6772.2012; IPM-2012 (October 10, 2012)", "url": "https://ntrs.nasa.gov/citations/20120016988", "year": 2012, "kind": "report", "license": "public domain (NASA)" }, "compoundsemi-2006": { "title": "AlGaN provides filter-free detection (Compound Semiconductor, article 84128)", "id": "Compound Semiconductor, published 27 June 2006", "url": "https://compoundsemiconductor.net/article/84128/AlGaN_provides_filter-free_detection", "year": 2006, "kind": "web", "license": "trade article, cited not reproduced" }, "techbriefs-gsc15673": { "title": "NASA Tech Briefs article, reference GSC-15673-1 (AlGaN solar-blind UV detector)", "id": "GSC-15673-1; NASA Tech Briefs Vol. 34 No. 10 (October 1, 2010)", "url": "https://www.techbriefs.com/component/content/article/8640-gsc-15673-1", "year": 2010, "kind": "web", "license": "public domain (NASA text)" }, "wiki-algan": { "title": "Aluminium gallium nitride (Wikipedia), used for composition only", "id": "Wikipedia, lead section", "url": "https://en.wikipedia.org/wiki/Aluminium_gallium_nitride", "year": 2026, "kind": "web", "license": "CC BY-SA 4.0" }, "usgs-mcs2026-gallium": { "title": "Mineral Commodity Summaries 2026, Gallium", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-gallium.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-mcs2026-aluminum": { "title": "Mineral Commodity Summaries 2026, Aluminum", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-crit2025": { "title": "About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)", "id": "Final 2025 List of Critical Minerals", "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals", "year": 2025, "kind": "web", "license": "public domain (USGS)" }, "ec-crm": { "title": "Critical raw materials (European Commission, Regulation (EU) 2024/1252)", "id": "Regulation (EU) 2024/1252", "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en", "year": 2024, "kind": "web", "license": "European Commission web page" }, "arxiv-lattice-0811": { "title": "Ab initio calculation of structural and electronic properties of AlxGa1-xN and InxGa1-xN alloys", "id": "arXiv:0811.0380; E. López-Apreza, J. Arriaga and D. Olguín (2008)", "url": "https://arxiv.org/pdf/0811.0380", "year": 2008, "kind": "paper", "license": "arXiv preprint" }, "arxiv-elastic-2510": { "title": "Evaluation of Structural Properties and Defect Energetics in AlxGa1-xN Alloys", "id": "arXiv:2510.25912; F. Reza, B. Chen and M. Jin (Pennsylvania State University, 2025)", "url": "https://arxiv.org/pdf/2510.25912", "year": 2025, "kind": "paper", "license": "arXiv preprint" }, "mpm-thermal-2022": { "title": "First-principles study of anisotropic thermal conductivity of GaN, AlN, and Al0.5Ga0.5N", "id": "Materials Physics and Mechanics 49(1), pp. 97-107; D. Hvazdouski, M.S. Baranava and V.R. Stempitsky (2022)", "url": "https://mpm.spbstu.ru/article/2022.89.7/", "year": 2022, "kind": "paper", "license": "not checked" }, "pubchem-gan": { "title": "Gallium nitride, PubChem CID 117559, GHS classification", "id": "PubChem CID 117559 (Gallium nitride)", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Gallium-nitride", "year": 2026, "kind": "database", "license": "PubChem public database" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/aluminium-gallium-nitride/" }