Indium arsenide is a narrow-gap III-V semiconductor that has become the default host material for three separate frontier device families: mid-infrared photodetectors, epitaxial quantum-dot photon sources, and superconductor-semiconductor hybrid quantum devices including Microsoft’s tetron qubits.
Summary
Indium arsenide (InAs) is a binary III-V compound semiconductor, grown epitaxially (typically by molecular beam epitaxy) either as a bulk layer, as a quantum well inside a heterostructure, or as self-assembled nanoscale islands (quantum dots) embedded in a wider-gap host such as GaAs or InP. It is used as a substrate, as an active layer, and as a lattice-matching reference for other epitaxial materials such as Heusler compounds grown for spintronics.
The parameters that decide InAs in each role differ. For detectors it is bandwidth, room-temperature sensitivity and structural simplicity. For thermoradiative and energy-harvesting diodes it is reverse saturation current relative to the radiative limit and breakdown voltage, both of which are still far from ideal. For quantum photonics it is dot inhomogeneity, cavity quality factor and the refractive-index mismatch that complicates coupling III-V gain material to standard silicon waveguides. For hybrid quantum devices it is interface quality, parasitic bulk conduction and electrostatic control.
Evidence base
- 6 May 2026: MBE-grown 1x1 mm2 InAs p-i-n thermoradiative diodes grown at 450 C reached breakdown voltages above 0.3 V but reverse saturation current densities 200 times the radiative limit.
- 14 May 2026: single photons deterministically generated from an InAs/GaAs quantum emitter produced a Bell-like noncontextual hidden-variable inequality violation of 380 standard deviations.
- 3 June 2026: a 20 second parity lifetime was reported in an InAs-Pb tetron device.
- 17 June 2026: a 121 µm diameter InAs/InAsSbP nBp barrier detector achieved 2.4 GHz -3 dB and 8.0 GHz -20 dB bandwidth at room temperature in the 3.0-3.7 µm band, with detection above 19 GHz, described as the best in its class confirmed optically on a mature InAs platform whose commercial supply remains scarce.
- 22 July 2026: dual-gated InAs/GaInSb/InAs trilayer quantum wells on AlSb quasi-substrates showed an insulating bulk and quantised edge resistance robust over a broad electric-field range.
- 24 July 2026: InAs quantum dots coupled to a waveguide-coupled InP microdisk gave 3.3x cavity enhancement and 0.985 emission directionality in the 1260-1360 nm telecom band, reported as the first chiral quantum interface at telecom wavelengths.
- 16 June 2026: first-principles work predicts magnetic Weyl semimetals outperforming InAs for magnet-free nonreciprocal infrared thermal radiation.
Open questions
- Can MBE growth optimisation close the gap between InAs thermoradiative diodes and the radiative limit, currently a factor of 200, and raise breakdown voltage well above 0.3 V?
- Does the 20 second parity lifetime measured in a single InAs-Pb tetron hold when the same stack is scaled to multi-qubit arrays with routing and readout?
- Will the proposed epitaxial design for coupling InAs/(Al)GaAs quantum dot gain to 220 nm silicon waveguides survive fabrication, or does CMOS compatibility force a different gain material?
- In functions where InAs is the incumbent benchmark, such as nonreciprocal thermal radiation, do the predicted alternatives (magnetic Weyl semimetals) actually reach device-grade material quality?
Assessment drafted 2026-08-31 from up to 16 KB sources using the technology-scorecard framework; scores are a draft read pending review.