Gallium antimonide (GaSb) is a narrow-bandgap III-V compound semiconductor with a direct bandgap of 0.73 eV at room temperature, corresponding to an emission wavelength of approximately 1.7 µm. Its lattice constant (0.610 nm) makes it the natural substrate for the entire antimonide heterostructure family (InAs/GaSb, InAsSb, AlGaAsSb) that spans 2–12 µm — the mid-wave and long-wave infrared atmospheric windows.
The device relevance is threefold. First, GaSb-based interband laser diodes (2–3.5 µm) and interband cascade lasers (ICLs) cover the molecular fingerprint region of most hydrocarbons, making them the emitter of choice for gas sensing (CH₄, CO₂, VOCs). Second, type-II superlattices (T2SL) grown on GaSb substrates enable high-sensitivity MWIR photodetectors with lower Auger recombination than bulk HgCdTe. Third, GaSb’s high hole mobility (~1,000 cm²/V·s) and narrow bandgap make it attractive for complementary III-V CMOS (p-channel transistors).
Brolis Semiconductors produces GaSb-based mid-IR laser diode bars and modules. The Mid Ir Photonic Sensing thesis tracks the commercial opportunity in molecular spectroscopy enabled by antimonide emitters. Indium Antimonide and Indium Arsenide are close lattice-matched siblings used in longer-wavelength detector applications.
Frontier
- Can GaSb-based laser diodes reach room-temperature CW operation reliably above 4 µm without costly substrate engineering?
- Does the III-Sb ecosystem develop sufficient foundry capacity to challenge HgCdTe dominance in MWIR imagers?
- What is the realistic path to monolithic integration of GaSb active regions on silicon substrates?