InPSubstraten

InP substraten, or indium phosphide substrates, are single-crystal wafers used as the foundation for growing III-V semiconductor layers. Indium phosphide is a direct-bandgap material with a room-temperature bandgap around 1.35 eV and a lattice constant near 5.8687 angstroms, which allows relatively good lattice matching to related compounds such as InGaAs and InGaAsP. These properties make InP a favored platform for optoelectronic devices in the near- to mid-infrared, including fiber-optic communications components.

Manufacturing and characteristics: InP substrates are produced by crystal growth methods such as the Czochralski process or other bulk crystal growth techniques, then sliced and polished into wafers. Common surface orientations include near (100), often with a deliberate off-cut to improve epitaxial growth, though other orientations are used for specific device schemes. Typical wafer diameters historically range from 2 to 3 inches, with larger diameters (up to about 4 inches) increasingly available as production scales expand. The wafers require careful cleaning and oxide removal before epitaxial deposition to ensure smooth, defect-free surfaces.

Applications and growth: InP substrates serve as the base for epitaxial layers of InGaAs, InGaAsP, or related alloys grown by molecular beam epitaxy (MBE) or metal-organic chemical vapor deposition (MOCVD). They are central to devices such as laser diodes, VCSELs, photodiodes, and photonic integrated circuits operating around 1.3 to 1.55 micrometers, which are important for telecom and sensing. InP-based HEMTs and other high-frequency devices also leverage this substrate technology. Processing challenges include surface oxide management and defect control, but InP remains a core platform for infrared photonics and integrated circuits.