GaInAs

GaInAs, often denoted Ga1−xInxAs, is a ternary III–V semiconductor alloy formed from gallium arsenide (GaAs) and indium arsenide (InAs). By varying the indium content x from 0 to 1, the alloy’s lattice constant and electronic properties can be tuned over a wide range. The material is typically grown epitaxially and can be strained or relaxed depending on the substrate and layer thickness.

Ga1−xInxAs is a direct bandgap semiconductor, making it particularly suitable for optoelectronic devices. The bandgap decreases from about 1.42 eV for GaAs (x = 0) toward about 0.36 eV for InAs (x = 1), with the dependence described by a bowing parameter. Temperature also affects the bandgap, shifting the absorption edge. This tunability enables infrared detection and emission across a broad spectrum, including the near to mid-infrared.

Lattice matching and growth considerations are important for GaInAs. The alloy’s lattice constant increases with indium content, which can introduce strain when grown on GaAs substrates, often limited to thin, pseudomorphic layers or buffered growth. When grown on InP, a common composition is In0.53Ga0.47As, which is lattice-matched to InP and widely used for telecom photonics. Common fabrication methods include molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD), enabling high-purity, precisely controlled layers and devices.

Applications span infrared photodetectors, high-speed photodiodes, laser and LED structures, and integrated optics for optical communications. GaInAs materials are also used in multijunction solar cells and other optoelectronic devices where a tunable, direct bandgap alloy is advantageous.