Physics / mechanism
Indium gallium arsenide (InGaAs) photodetectors exploit the direct bandgap of In₀.₅₃Ga₀.₄₇As lattice-matched to InP substrates. The bandgap (~0.74 eV) gives absorption from ~900 nm to 1700 nm; extending In content to ~0.82 shifts cutoff to ~2.6 µm (extended SWIR) at the cost of lattice mismatch and dark current. Core figures of merit: quantum efficiency >80%, dark current density <1 nA/cm² at room temperature for standard compositions, noise-equivalent irradiance in the 10⁻¹⁰ W/cm² range. FPAs ship at 640×512 and 1280×1024 formats; pixel pitches have compressed to 5 µm. ROIC integration (InGaAs flip-bonded to Si CMOS) is the dominant packaging architecture. Key producers: Sensors Unlimited (UTC/Collins), Vigo, Leonardo DRS, Hamamatsu, and SWIR Vision Systems.
Competitive landscape
InGaAs competes primarily on cost and operating temperature against three alternatives:
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Frontier (open questions)
- To be added.