InGaAs

InGaAs, or indium gallium arsenide, is a ternary III-V semiconductor alloy with the formula InxGa1−xAs, where 0 ≤ x ≤ 1. It combines indium, gallium, and arsenic in a zinc blende crystal structure and is widely used in infrared optoelectronics. The bandgap is direct and can be engineered by adjusting the indium content and by strain from lattice matching to a substrate. The bandgap ranges from about 0.36 eV for InAs to about 1.42 eV for GaAs, with In0.53Ga0.47As (approximately x = 0.53) commonly grown lattice-matched to GaAs and having a bandgap near 0.75 eV, corresponding to an absorption edge near 1.65 µm. This makes InGaAs suitable for detectors and photodiodes operating in the near- and short-wave infrared, including the 1.3–1.55 µm telecommunications window.

Growth and substrates: InGaAs is typically grown by molecular beam epitaxy (MBE) or metal-organic chemical vapor deposition (MOCVD). It can be grown on GaAs substrates (where x ≈ 0.53 yields lattice matching) or on InP with appropriate buffer layers. Strain from lattice mismatch can modify the band structure and device performance.

Applications: Key applications include high-speed infrared photodetectors, photodiodes, and image sensors, as well as active layers in quantum-well and laser structures when integrated with other III-Vs. Material quality and defect density depend on growth conditions and substrate choice.