InP

Indium phosphide (InP) is a binary III-V semiconductor compound composed of indium and phosphorus. It crystallizes in the zinc blende structure and is widely used in optoelectronic and high-speed electronic devices because of its direct bandgap and favorable electron transport properties.

At room temperature, InP has a direct bandgap of about 1.35 eV, placing its intrinsic emission in the near-infrared. The crystal lattice constant is approximately 5.8687 angstroms. Its refractive index is around 3.1 in the near-infrared range, and it exhibits high electron mobility on the order of several thousand square centimeters per volt-second. Thermal conductivity is about 68 W/m·K, and the dielectric constant is roughly 12.5. These properties, together with a direct bandgap, make InP suitable for high-speed electronics and infrared light emission.

InP wafers are grown predominantly by crystal growth methods such as the Czochralski or Bridgman techniques. Epitaxial layers are deposited by metalorganic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE) to form binary InP or ternary/quaternary alloys (for example InGaAsP) that are engineered for specific wavelengths. Heteroepitaxy on InP substrates or on matched buffers enables devices operating in the 1.0–1.6 micrometer telecom window.

Applications of InP include laser diodes and photodetectors for optical fiber communications, high-speed integrated circuits, and infrared sensors. InP-based materials are also used in multi-junction solar cells for space and terrestrial applications, where radiation hardness and compatible lattice structures are advantageous.

Safety and handling notes apply, as precursors such as phosphine are toxic and require proper control during synthesis and processing.