Gallium arsenide (GaAs) is a compound of the elements gallium and arsenic. These two elements combine and form III-V semiconductor with a zinc blende crystal structure. Gallium Arsenide (GaAs) is one of the most important compound semiconductor materials in the world- it is widely used in many applications in wireless, opto-electronics, and Solar Cells. Gallium arsenide (GaAs) can be supplied as ingots or ingot sections or as cut, etched or polished wafers and are individually laser scribed with ingot and slice identity. Gallium arsenide (GaAs) wafers possess a combination of superior properties such as high electron mobility, direct band gap, high conversion efficiency, and high frequency with less noise.
Three methods can prepare gallium arsenide: the vertical gradient freeze (VGF), the Bridgman-Stockbarger technique and liquid encapsulated Czochralski (LEC) growth.
- The most common process for producing GaAs wafers is The VGF technique. This method differs from any other growth method by the fact that it produces crystals with a much lower dislocation density. It involves growing crystals to a specific diameter and then thinly slicing it to very precise tolerances, edge rounding the form factors, and finally - polishing and packaging the wafers.
- In the Bridgman-Stockbarger method, the crystals are grown in a horizontal zone furnace allowing the gallium and arsenic vapors to react and then on a seed crystal cooler at the end of the furnace, the free molecules are deposited.
- The LEC growth method produces high-purity single crystals that are capable of exhibiting semi-insulating characteristics.
The required electrical properties, depending on the application, are obtained by adding dopants such as carbon, silicon, tellurium or zinc resulting in a p-type or n-type high-resistance (>107 Ωcm) or low-resistance (<10-2 Ωcm) semiconductors. The wafer surfaces are normally epi-ready (extremely low contamination) i.e. their quality suits the direct use in epitaxy processes.
Gallium Arsenide Wafers Benefits Over Silicon:
1) GaAs, with its direct band-gap properties makes all-optical buses direct light on-chips much more efficiently than do wires on silicon.
2) GaAs moves electrons faster with less consumed power. Think of your mobile tech such as cell phones or smart watches with tight inner spaces and short battery life. GaAs offers a real advantage over silicon for some components.
GaAs is highly useful in the field of high-speed circuits alongside with systems that incorporate ultrathin GaAs chips in the front end.
- GaAs wafers are used in optoelectronics.
- GaAs wafers are used in microwave frequency ICs
- GaAs wafers are used in monolithic microwave ICs
- GaAs wafers are used in manufacture of MESFET (metal semiconductor field-effect transistor) ()
- GaAs wafers are used in manufacture of HEMT (High Electron Mobility Transistor)
- GaAs wafers are used in manufacture of HBT (Heterojunction Bipolar Transistor)
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