GaAs vs InP: Choosing the Right III-V Substrate
Choosing between gallium arsenide (GaAs) and indium phosphide (InP) comes down to wavelength and frequency: GaAs is the workhorse for RF power amplifiers, MMICs, and shorter-wavelength optoelectronics (around 850 nm), while InP is the required platform for long-haul fiber-optic components operating at 1310 nm and 1550 nm, and for the highest-frequency electronics. GaAs substrates are more mature, available in larger diameters, and cost less; InP delivers higher electron velocity and direct-bandgap emission at telecom wavelengths that GaAs cannot reach.
When should you choose GaAs?
GaAs suits applications where cost, substrate maturity, and moderate frequency dominate: RF power amplifiers for handsets and base stations, MMICs, VCSELs for short-reach datacom (850 nm), LEDs, and space-grade photovoltaics. Semi-insulating GaAs substrates support monolithic microwave circuits, and the supply chain is deep — substrates are available up to 6" with well-established epi processes.
When is InP the right platform?
InP is the default wherever 1310/1550 nm telecom wavelengths or extreme speed are involved: laser diodes and photodetectors for long-haul and metro fiber networks, coherent optics, photonic integrated circuits (PICs), and HEMT/HBT electronics pushing past 100 GHz. Its higher electron velocity also makes it the choice for the fastest transistors and for emerging co-packaged optics in AI data centers — a demand driver that has tightened InP substrate supply.
GaAs vs InP at a glance
| Property | GaAs | InP |
|---|---|---|
| Bandgap | ~1.42 eV (direct) | ~1.34 eV (direct) |
| Native emission window | ~850–870 nm | 1310/1550 nm (with lattice-matched InGaAsP/InGaAs epi) |
| Electron mobility | ~8,500 cm²/V·s | ~5,400 cm²/V·s (but higher peak electron velocity) |
| Typical diameters | 2"–6" | 2"–4" (6" emerging) |
| Relative substrate cost | Lower | Higher (smaller boules, more fragile) |
| Signature applications | RF PAs, MMICs, VCSELs, LEDs, space PV | Telecom lasers/detectors, PICs, 100+ GHz electronics |
| Handling | Brittle; standard III-V care | More fragile than GaAs; extra care in thinning/dicing |
What about GaSb, InAs, and InSb?
For infrared work beyond InP's range, the antimonide/arsenide family takes over: GaSb substrates anchor mid-IR lasers and thermophotovoltaics, InAs supports mid-IR detectors and quantum structures, and InSb delivers the highest electron mobility of any common III-V — the basis of magnetic sensors and long-wave IR detectors. Mihron Metalyx sources all three alongside GaAs and InP.
Sourcing III-V substrates in North America
Mihron Metalyx supplies GaAs (semi-insulating, n-type, p-type), InP (SI, n-type, p-type), and GaSb/InAs/InSb substrates in 2"–6" diameters, epi-ready, VGF and LEC grown, from a bonded Toronto warehouse at 2967 Dundas St. W. #141B, Toronto. Every lot ships with a Certificate of Analysis, and quotes return within 48 hours.
Frequently asked questions
Is GaAs or InP better for fiber-optic components?
InP. Long-haul and metro fiber networks operate at 1310 nm and 1550 nm, wavelengths that require InP-based lasers and photodetectors with lattice-matched InGaAsP or InGaAs epitaxy. GaAs emits around 850 nm and is limited to short-reach links.
Why does InP cost more than GaAs?
InP boules are smaller, the material is more fragile to process, and demand from telecom and AI data-center optics is high relative to supply. GaAs benefits from decades of volume production for RF and LED markets.
Which substrate should I use for RF power amplifiers?
GaAs for most PA applications up to tens of GHz — it is the mature, cost-effective choice for handset and base-station PAs and MMICs. InP HEMTs and HBTs take over when designs push beyond roughly 100 GHz.
Can I get semi-insulating GaAs and InP in Canada?
Yes — Mihron Metalyx stocks and sources semi-insulating, n-type, and p-type GaAs and InP substrates from a bonded Toronto warehouse, shipping across Canada and the US in 3–5 business days for stock material.
Sourcing III-V substrates?
GaAs, InP, GaSb, InAs, InSb — quotes in 48 hours.