Physics / mechanism
GaAs is a III-V direct-bandgap semiconductor (Eg ≈ 1.42 eV at 300 K) with electron mobility ~8500 cm²/V·s—roughly 6× silicon. Direct bandgap enables efficient radiative recombination, making it the substrate of choice for near-IR lasers (750–900 nm), VCSELs, and high-efficiency photovoltaics. Epitaxial stacks grown by MBE or MOCVD achieve threshold current densities <200 A/cm² in edge-emitters; VCSEL wall-plug efficiencies reach ~60% at 850 nm. Multi-junction GaAs solar cells exceed 47% efficiency under concentration. RF-photonic integration exploits high-speed Schottky junctions and low parasitic capacitance. Wafer sizes have reached 6-inch production with 8-inch in qualification at select fabs.
Competitive landscape
GaAs competes directly with InP (dominant at 1310/1550 nm for telecom), GaN (power, short-wavelength), and silicon photonics (cost, CMOS integration). Emerging GaN-on-Si threatens GaAs in some mm-wave + photonic co-integration scenarios.
Companies using
Connected ideas
Sources
Frontier (open questions)
- To be added.