Galliumarseniid

Galliumarseniid, more commonly known as gallium arsenide (GaAs), is a binary compound of gallium and arsenic and a III-V semiconductor. It is widely used in optoelectronic and high-speed electronic devices due to its direct bandgap and favorable carrier properties.

Crystal structure and properties: GaAs crystallizes in the zinc blende structure. At room temperature its lattice constant is about 5.653 Å. It has a direct bandgap of approximately 1.42 eV (about 0.87 μm) at 300 K, which enables efficient light emission and absorption in the near-infrared region. Electron mobility is high (roughly 850 cm2/Vs) with a lower hole mobility (around 400 cm2/Vs). The refractive index is near 3.3 in the near-infrared. These properties make GaAs suitable for light-emitting diodes, laser diodes, and high-speed electronics.

Fabrication and doping: GaAs is grown by methods such as molecular beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), and, historically, liquid phase epitaxy. It can be doped to form n-type or p-type materials, using dopants like silicon (n-type) or zinc/beryllium (p-type). Alloying with aluminum or indium (e.g., AlGaAs, GaInAs) tunes the bandgap and lattice matching for heterostructures and quantum wells.

Applications: GaAs is central to infrared and visible optoelectronics, including LEDs and laser diodes, photodetectors, and high-speed transistors and integrated circuits. GaAs-based solar cells, particularly in space and specialized applications, offer high efficiency and radiation tolerance.

Safety and handling: Arsenic-containing compounds are toxic. Handling requires proper ventilation, protective equipment, and appropriate waste disposal. Careful control of exposure and compliance with safety regulations are essential.