Indium antimonide (InSb) is a narrow-bandgap III-V compound with a direct bandgap of ~0.17 eV at room temperature (0.23 eV at 77 K), placing its intrinsic photoresponse in the 3–5 µm mid-wave infrared band. It holds the record for highest room-temperature electron mobility among binary semiconductors (~77,000 cm²/V·s), and the effective electron mass is among the lowest known (~0.014 m₀), making it a textbook material for high-speed electronics.
Three application pillars define its investment relevance. For infrared imaging, InSb photovoltaic focal-plane arrays (FPAs) are mature, foundry-proven MWIR detectors widely deployed in military and scientific instruments; Scd Semiconductor Devices is an established InSb FPA manufacturer. For quantum computing, InSb nanowires are a leading host platform for Majorana zero modes — non-Abelian anyons proposed as topologically protected qubits — motivating significant research investment (notably Microsoft); this connection is tracked under Topological Qubits (Microsoft Majorana) and Topological Insulators. For transistors, the ultrahigh mobility enables low-power III-V CMOS p-channel devices in advanced node research.
The material is brittle, has poor thermal conductivity (~18 W/m·K), and requires cryogenic cooling for peak detector performance, constraining wafer yield and system integration relative to silicon-based alternatives.
Frontier
- Will InSb nanowire-based topological qubits achieve fault-tolerant operation before competing approaches (Si spin, transmon) reach similar fidelity?
- Can InSb focal-plane arrays displace HgCdTe in volume defence programs on cost grounds as LWIR volumes scale?
- Does the extreme electron mobility of InSb translate to a commercial high-speed transistor advantage?