| HS Code | 829072 |
| Chemical Name | Trimethylindium |
| Chemical Formula | In(CH3)3 |
| Cas Number | 3385-78-2 |
| Molecular Weight | 159.93 g/mol |
| Appearance | Colorless to white crystalline solid or transparent liquid depending on temperature |
| Melting Point | 89.6 °C |
| Boiling Point | 134 °C |
| Density | 1.568 g/cm3 at 20 °C |
| Vapor Pressure | 16.9 mmHg at 40 °C |
| Purity | 99.999% (5N) |
| Electronic Grade | EL Grade for MOCVD epitaxial growth |
| Packaging Note | Stainless steel bubbler under inert atmosphere |
As an accredited Trimethylindium (TMIn) Electronic/EL Grade factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Sealed stainless steel bubbler containing 100g Trimethylindium (TMIn), Electronic/EL Grade, with inert gas connections for safe handling. |
| Container Loading (20′ FCL) | Container Loading (20′ FCL) for Trimethylindium Electronic/EL Grade: secure upright cylinders, ensure inert gas purge, and comply with hazmat regulations. |
| Shipping | Trimethylindium (TMIn) Electronic/EL Grade is shipped in sealed stainless steel or glass cylinders under inert gas or vacuum to prevent air/moisture exposure. Due to its pyrophoric and toxic nature, transport follows strict hazardous material regulations, with proper labeling, leakage containment, and dedicated handling to ensure safety. |
| Storage | Trimethylindium (TMIn) is pyrophoric and moisture-sensitive. Store in sealed, corrosion-resistant containers under inert gas (nitrogen/argon) in a cool, dry, well-ventilated area away from oxidizers, water, and ignition sources. Use approved flammable storage cabinets, maintain leak integrity, and follow manufacturer instructions to prevent hazardous decomposition or exposure. |
| Shelf Life | Shelf life is typically 6–12 months when stored unopened under inert gas, protected from moisture and oxygen. |
Electronic/EL grade trimethylindium is supplied in electropolished 316L stainless steel bubblers with helium leak rates below 1×10−9 mbar L s−1, dip-tube withdrawal, and union-nut outlet connections that permit gas panel integration without atmospheric exposure. The precursor is pyrophoric; bubbler change-out and line purging are performed under inert atmosphere until dew point sensors record less than −70°C. In InGaN multi-quantum well epitaxy for blue and green light-emitting diodes, TMIn is transported from a temperature-controlled bath held at 20–30°C, where the vapor pressure is approximately 1–2 Torr, through a pressure-based mass flow controller into a close-coupled showerhead reactor such as a Veeco K465i or Aixtron Crius II-R. The reactor is configured for 6×2 in or 19×2 in platen capacity, and run-to-run indium composition reproducibility is governed by carrier gas line pressure, bubbler fill level, and condensed-phase temperature stability rather than by flow set point alone. Blue-emitting wells are deposited at 740–790°C with indium fractions of 0.15–0.20, total pressure between 100 and 500 Torr, and an ammonia-to-total-group-III ratio above 10,000:1 to suppress InN phase segregation and maintain step-flow growth on GaN templates. Green-emitting wells with indium fractions of 0.25–0.35 require a 20–50°C reduction in surface temperature to limit indium desorption, but this conflicts with ammonia pyrolysis efficiency, so the process is shifted toward higher NH3 partial pressure and lower total pressure. Oxygenated TMIn impurities such as methoxydiethylindium or ether adducts introduce non-radiative recombination centers and broaden dominant-wavelength distribution across a 4 in or 6 in wafer. Incoming lots are qualified by ICP-MS for 99.9999% minimum indium purity, Fourier-transform infrared spectroscopy for oxygenated organic residues, and gas chromatography–mass spectrometry for volatile homologues, with acceptance criteria aligned to SEMI C47 precursor quality guidelines. Terminal epi wafers are processed into lateral and vertical LED chips; across-platen indium content is held within ±1.0% absolute to maintain dominant-wavelength bin widths of 5 nm or less in packaged devices.
In phosphorus-containing MOCVD for indium phosphide ridge-waveguide and buried-heterostructure lasers, the TMIn source is paired with phosphine and arsine in a high-temperature process chamber operated at 600–650°C and 50–100 Torr. The InP/InGaAsP/InAlGaAs material system requires lattice-matched indium molar fractions that vary from 1.0 in binary InP to 0.53 in In0.53Ga0.47As and to lower indium fractions in quaternary InGaAsP, so the TMIn delivery system must hold temperature stability within ±0.1°C and line pressure within ±5 Torr. Abrupt heterointerfaces for multi-quantum well active regions and distributed-feedback grating overgrowth are produced with vent/run pressure-balanced switching manifolds and fast gas phase residence times below 0.5 s; residual indium memory effects from TMIn decomposition in the delivery line are minimised by heated lines above 60°C and periodic solvent-free purging. Electronic/EL grade TMIn used in this application is subject to oxygenated compound limits tighter than those required for gallium-only MOCVD because oxygen-related deep levels shorten non-equilibrium carrier lifetime in the active region. InGaAsP laser structures with 5–8 quantum wells are grown at V/III ratios between 30:1 and 200:1, with n-type InP cladding layers doped by silane and p-type InP cladding layers doped by diethylzinc. Terminal photonic integrated circuits include distributed-feedback lasers, electro-absorption modulators, semiconductor optical amplifiers, and butt-jointed waveguides; long-term reliability is qualified under Telcordia GR-468-CORE, with TMIn lot-to-lot photoluminescence screening used to reject precursor-related non-radiative defect formation.
The transition from depletion-mode to enhancement-mode InGaAs pseudomorphic high-electron-mobility transistor channels on 150 mm GaAs substrates places a hard boundary on epitaxial sheet resistance and Hall mobility because parasitic source–drain resistance directly degrades the noise figure of monolithic microwave integrated circuits. TMIn is delivered to a multi-wafer MOCVD reactor at 500–600°C and 40–100 Torr with arsine as the group-V source; the indium fraction in the strained InxGa1−xAs channel is typically 0.17–0.22 for GaAs-based pHEMTs or 0.53 for InP-based HEMTs, depending on the target conduction-band offset. Sheet resistance below 220 Ω/sq at 300 K requires channel thickness and doping to be constrained with atomic precision, and the TMIn source must not contribute silicon-, zinc-, or oxygen-containing impurities that shift threshold voltage or reduce mobility. Batch-to-batch variation in TMIn vapor-phase composition is monitored by an Epison acoustic concentration sensor or an ultrasonic concentration monitor downstream of the bubbler; deviations greater than 2% from the baseline trigger abort of the growth run. The V/III ratio is maintained between 10:1 and 100:1 for InGaAs growth, and the reactor is operated in a hydrogen carrier gas with oxygen and moisture below 10 ppb. Low growth temperature is necessary to preserve abrupt delta-doping planes but can elevate carbon incorporation; therefore the process uses lower TMIn partial pressure and higher arsine partial pressure within the stated V/III window. Terminal devices include low-noise amplifiers for 28 GHz and 39 GHz 5G front ends, W-band radar ICs, and direct-conversion receivers; qualification data for epitaxial wafers are recorded under lot-level Hall effect measurements and photoluminescence mapping according to ASTM F76-08.
For short-wave infrared photodiode growth on indium phosphide substrates, the decision to accept a TMIn lot is driven by dark current and shunt resistance yield at the device level, not solely by certificate-of-analysis metal purity. The absorber is an In0.53Ga0.47As layer lattice-matched to InP at room temperature with a misfit strain below 5×10−4; growth occurs at 600–650°C and 60–100 Torr using TMIn, trimethylgallium, and arsine, with an overall V/III ratio of 20:1 to 60:1. The p-i-n photodiode structure uses a 2.5–3.5 µm unintentionally doped absorber with background carrier concentration below 1×1015 cm−3, which is achievable only when oxygenated TMIn decomposition products are suppressed to levels that do not generate deep donors. Incoming TMIn is tested for oxygenate content by Fourier-transform infrared spectroscopy and for transition-metal contamination by ICP-MS; typical acceptance limits reject lots with oxygenated organic residuals above 10 ppmw and key metal impurities above 0.5 ppmw. A 75 µm diameter InGaAs photodiode with a 1.7 µm cutoff is expected to exhibit dark current below 10 nA at 5 V reverse bias and shunt resistance above 0.5 MΩ, but these values degrade by one to two orders of magnitude if the TMIn source introduces non-radiative recombination centers or surface states. Device processing includes silicon nitride passivation and planar or mesa isolation; epi qualification therefore requires wafer-level dark current mapping and visual inspection under ISO 14644-1 class 5 or better cleanroom conditions. Terminal devices are packaged as single-element detectors, 512-element line-scan arrays, and 640×512 focal plane arrays for spectroscopy, process control, and optical coherence tomography.
Direct-bandgap InGaP and InGaAs subcells in terrestrial concentrator and space photovoltaic stacks are grown with TMIn as the indium source for the top and middle cell compositions. In0.49Ga0.51P top cells lattice-matched to germanium are deposited at 650–700°C with TMIn, triethylgallium or trimethylgallium, and phosphine; the middle In0.01Ga0.99As cell is deposited at 500–650°C with arsine. V/III ratios are maintained between 30:1 and 150:1, and reactor pressure is held at 50–100 Torr. Tunnel junctions require high doping and abrupt n++/p++ interfaces, so TMIn purity directly affects both zinc and silicon dopant incorporation efficiency and the background impurity level that reduces peak tunneling current. For space-grade triple-junction InGaP/InGaAs/Ge solar cells, AM0 conversion efficiency is typically certified in the 29–32% range depending on cell size and radiation-hardness requirements. Lot acceptance for the metalorganic precursor involves ICP-MS, Fourier-transform infrared spectroscopy, and particle counting; because the process is run on production reactors with quartz or silicon carbide-coated graphite susceptors, any indium-containing particulate or non-volatile residue leaves a visible ring on the reactor wall and shifts subsequent tunnel-junction doping. The terminal wafers are processed into 30 cm² class cells for concentrator photovoltaics and smaller area cells for low-Earth-orbit and geostationary satellite arrays; qualification follows electrical performance testing under ASTM E2236 and environmental aging per ECSS E-ST-20-08 where applicable.
Because type-II InAs/InAsSb strained-layer superlattices on GaSb substrates are deposited at 400–480°C, close to the thermal decomposition threshold of TMIn, the indium precursor delivery system must maintain a narrow process window for stable indium incorporation. The group-V precursor mixture of arsine and trimethylantimony is introduced with V/III ratios between 5:1 and 20:1; high antimony partial pressures are required to nucleate InAsSb, but excess antimony segregates on the growing surface and increases defect density. TMIn is delivered from a low-temperature bubbler at 15–25°C with reduced carrier gas flow to avoid condensation and stabilise the indium molar flux across the susceptor. Across a 3 in or 4 in GaSb wafer, a temperature non-uniformity of ±5°C changes the InAsSb alloy composition by more than 0.5%, shifting the detector cutoff wavelength outside the 4–5 µm atmospheric window. Electronic/EL grade TMIn with oxygen and moisture below specified CoA limits is necessary to keep the unintentional n-type background concentration below 5×1015 cm−3; oxygen and water vapor decompose TMIn to indium oxide particles that become embedded at superlattice interfaces. Grown structures are characterised by high-resolution X-ray diffraction, photoluminescence, and Hall effect measurements before fabrication into focal plane arrays with indium bump bonding and anti-reflection coating. The terminal detectors are used in methane and carbon dioxide imaging, industrial thermal monitoring, and defense optical systems; qualification of substrate temperature uniformity follows in situ pyrometry traceable to NIST-calibrated blackbody references.
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Trimethylindium (TMIn) Electronic/EL Grade, CAS 3385-78-2, formula In(CH3)3, molecular weight 159.93 g/mol, is a metalorganic precursor supplied as a white to off-white crystalline solid for metalorganic vapour-phase epitaxy (MOVPE) and metalorganic chemical vapour deposition (MOCVD) of indium-bearing III-V semiconductor films. The Electronic/EL designation identifies material qualified for optoelectronic and electronic device fabrication, including InGaN quantum-well LEDs, laser diodes, InP/InGaAs photodetectors, InAs/InSb infrared detectors, and InAlN/GaN high-electron-mobility structures. The material is packaged in electropolished stainless-steel bubblers with metal diaphragm valves; commercial model designations vary by supplier and are commonly referenced as TMIn-EL, TMIn Electronic Grade, or TMIn-EPI. Because the solid melts near 88 °C and has a low vapour pressure near ambient temperature, the source is usually operated as a heated bubbler or in a sublimation delivery configuration. The Electronic/EL Grade differs from technical-grade trimethylindium in that each lot is certified for trace-metal contamination, oxygenated organic species, halide content, and particle level. The following sections define the specification logic and process boundaries that govern its use in production epitaxy.
Electronic/EL Grade TMIn is not defined by a single universal specification; acceptance bands are set in supplier-specific quality agreements. The common frame is a minimum indium assay of 99.9999% (6N) on a metals basis, determined by inductively coupled plasma mass spectrometry after controlled digestion. Total trace-metal content is typically limited to ≤ 1.0 ppm, with individual critical transition and alkali metals held to ≤ 0.5 ppm because silicon, zinc, tin, and magnesium act as shallow donors or acceptors in III-V layers. Oxygenated organic impurities are controlled because alkoxide or oxo-bridged indium species can transport oxygen into the epitaxial layer. Typical acceptance bands are ≤ 100 ppm for total oxygenated organic impurities by Fourier-transform infrared or 1H nuclear magnetic resonance, but exact limits are lot-specific. Halides from synthesis are typically specified at ≤ 5 ppm by ion chromatography. Particle content is measured on a dilute solution or vapour-phase sample; a representative limit is ≤ 10 particles/mL at ≥ 0.5 µm. The lot certification therefore provides a narrower impurity envelope than technical-grade material, where trace-metal or oxygenated-organic data may be absent or reported only as total metals.
| Parameter | Representative Electronic/EL Grade specification | Analytical method |
|---|---|---|
| Indium assay, metals basis | ≥ 99.9999% | ICP-MS |
| Total trace metal impurities | ≤ 1.0 ppm, supplier-specific | ICP-MS |
| Individual critical transition and alkali metals | ≤ 0.5 ppm each, typical | ICP-MS |
| Oxygenated organic impurities | ≤ 100 ppm, typical acceptance band | FTIR, 1H NMR |
| Total halides | ≤ 5 ppm | ion chromatography |
| Particle content | ≤ 10 particles/mL at ≥ 0.5 µm | laser particle counter |
| Appearance | white to off-white crystalline solid | visual |
In production MOCVD systems, TMIn is most commonly delivered from a heated stainless-steel bubbler. The solid charge is held at temperatures between 25 °C and 40 °C, with hydrogen or nitrogen carrier gas passed through the container. Because the vapour pressure of TMIn is strongly temperature-dependent, bubbler temperature stability directly controls the molar flow of indium precursor into the reactor. A drift of ±0.2 °C in source temperature can shift the saturated vapour concentration enough to alter indium incorporation in composition-sensitive layers such as InGaN quantum wells. The gas manifold between the bubbler and reactor must be heat-traced at least 10–20 °C above the bubbler setpoint to prevent condensation of TMIn vapour or re-solidification of sublimed material. Condensation in insufficiently heated lines produces particle excursions and transient indium flow instability. Pressure-controlled operation is preferred because manual needle-valve control of a low-vapour-pressure solid source creates a non-linear flow response that complicates run-to-run repeatability. Carrier gas flow is typically set in the range of 20 sccm to 500 sccm, depending on reactor volume and target growth rate; low-flow operation may require dilution lines to maintain mass flow controller accuracy. When the bubbler is operated below the solid melting point, the material is consumed by sublimation, which can leave channelized solids and variable contact with the carrier gas. Production lines therefore use shallow-bed or reverse-flow bubbler geometries to reduce headspace and improve vapour saturation. Published data for specific bubbler geometric configurations is limited; vendors qualify container performance against pressure-drop and saturation curves under defined temperature and flow conditions.
In GaN/InGaN multi-quantum-well growth on 150 mm and 200 mm production wafers, the indium molar fraction in the solid is controlled by substrate temperature, total reactor pressure, inlet V/III ratio, and precursor partial pressure. Typical InGaN quantum-well deposition temperatures fall between 700 °C and 800 °C; lower growth temperatures increase indium incorporation but also increase the defect density if the thermal budget is insufficient for surface mobility. The TMIn source must therefore provide a stable indium partial pressure during the quantum-well growth step, because indium composition drift of ±0.5% can shift the emission wavelength beyond the production acceptance window. For InP/InGaAs device layers, growth temperatures are commonly between 600 °C and 650 °C, and the precursor is used with phosphine or arsine in low-pressure reactors. The Electronic/EL Grade material is selected over lower-cost technical material when the device stack includes a high-gain active region or a low-background detector structure, where metal impurities can change carrier concentration or dark current. In production epilayers, silicon contamination from a low-purity precursor can produce n-type background doping; zinc or cadmium can act as p-type dopants or recombination centres. The tolerance for any single impurity depends on the layer design, growth rate, and intentional doping level, so a single universal purity limit does not guarantee device performance. Lot-to-lot source consistency is evaluated by growing a reference layer and measuring sheet carrier concentration, mobility, and photoluminescence wavelength; this is performed on the production reactor because the impurity response is reactor-specific.
Trimethylindium differs from triethylindium (TEIn) and from technical-grade indium sources in both physical state and delivery behaviour. TEIn is a liquid at ambient temperature, which simplifies bubbler refill and avoids sublimation-channeling effects, but its vapour pressure is lower than that of TMIn at common bubbler setpoints. As a result, TEIn is selected when a lower indium molar flow is acceptable or when liquid-source handling is preferred; TMIn is selected when a higher indium delivery rate is required for high indium fraction layers. Ethyldimethylindium and other mixed alkyl precursors have been evaluated for reduced carbon incorporation or modified decomposition chemistry, but their use is less common in production and published data for specific device configurations is limited. The Electronic/EL Grade designation further separates certification practice from technical-grade material: technical grade may be adequate for R&D oxide or chalcogenide deposition where the substrate is not electrically active, but it is generally unsuitable for optoelectronic device epitaxy because oxygenated species and trace metals are not controlled to the same lot-specific level. The comparison below summarises the principal differences.
| Property | Electronic/EL Grade TMIn | Technical Grade TMIn | Triethylindium |
|---|---|---|---|
| Physical state at 25 °C | solid | solid | liquid |
| Typical purity | ≥ 99.9999% | 99.9% to 99.99%, varying | ≥ 99.999%, supplier-specific |
| Vapour delivery | heated bubbler/sublimation | heated bubbler | heated bubbler, lower vapour pressure |
| Oxygenated impurity specification | lot certified | often not reported | lot certified |
| Primary use | LED, laser, HEMT epitaxy | R&D, non-critical deposition | alternative indium source where lower vapour pressure is acceptable |
Storage of Electronic/EL Grade TMIn requires a dry, oxygen-free environment. The material is pyrophoric and reacts violently with water, alcohols, and oxidising solvents; all transfers must be performed in an inert atmosphere or using closed-container procedures. Cylinder connections should be purged with purified argon or nitrogen, and the supplier's leak-test and valve-torque procedures should be followed. The material is typically classified under Regulation (EC) No 1272/2008 as a pyrophoric solid and water-reactive substance; hazard labelling and emergency response must reflect that classification. The maximum recommended storage temperature is below the melting point unless the container is specifically designed for molten-state delivery. Once a bubbler is opened, the material should not be returned to long-term storage because moisture ingress can form indium oxide or hydroxide species that alter the vapour composition and generate particles. If the laboratory ambient relative humidity exceeds 60%, transfer operations should be avoided or conducted in a purged glovebox. The container, valve, and downstream gas lines must be periodically checked for particulate deposition and valve stem leakage. Disposal of residues must follow national and local regulations for pyrophoric metalorganics, with controlled hydrolysis under inert dilution and neutralisation of the resulting aqueous indium stream. The quality system of the supplier is typically certified to ISO 9001:2015; environmental management certification to ISO 14001:2015 does not itself validate precursor purity but provides a controlled manufacturing framework.
