Alternative methods for producing films of GaAs include :
Wet etching of GaAs industrially uses an oxidising agent e.g. hydrogen peroxide or bromine water, and the same strategy has been described in a patent relating to processing scrap components containing GaAs where the Ga3+ is complexed with a hydroxamic acid, "HAe.g.:
Oxidation of GaAs occurs in air and degrades performance of the semiconductor, the surface can be passivated by depositing a cubic gallium(II) sulfide layer using a tert-butyl gallium sulfide compound such as (tBuGaS)7
Another advantage of GaAs is that it has a direct band gap, which means that it can be used to emit light efficiently. Silicon has an indirect bandgap and so is very poor at emitting light. (Nonetheless, recent advances may make silicon LEDs and lasers possible).
Due to its high switching speed, GaAs would seem to be ideal for computer applications, and for some time in the 1980s many thought that the microelectronics market would switch from silicon to GaAs. The first attempted changes were implemented by the supercomputer vendors Cray Computer Corporation, Convex, and Alliant in an attempt to stay ahead of the ever-improving CMOS microprocessor. Cray eventually built one GaAs-based machine in the early 1990s, the Cray-3, but the effort was not adequately capitalized, and the company filed for bankruptcy in 1995.
Complex layered structures of gallium arsenide in combination with aluminium arsenide (AlAs) or the alloy AlxGa1-xAs can be grown using molecular beam epitaxy (MBE) or using metalorganic vapour phase epitaxy (MOVPE). Because GaAs and AlAs have almost the same lattice constant, the layers have very little induced strain, which allows them to be grown almost arbitrarily thick.
The second major advantage of Si is the existence of silicon dioxide—one of the best insulators. Silicon dioxide can easily be incorporated onto silicon circuits, and such layers are adherent to the underlying Si. GaAs does not form a stable adherent insulating layer.
The third, and perhaps most important, advantage of silicon is that it possesses a much higher hole mobility. This high mobility allows the fabrication of higher-speed P-channel field effect transistors, which are required for CMOS logic. Because they lack a fast CMOS structure, GaAs logic circuits have much higher power consumption, which has made them unable to compete with silicon logic circuits.
Complex designs of AlxGa1-xAs-GaAs devices can be sensitive to infrared radiation (QWIP).
GaAs diodes can be used for the detection of x-rays.
Single crystals of gallium arsenide can be manufactured by the Bridgeman technique, as the Czochralski process is difficult for this material due to its mechanical properties. However, an encapsulated Czochralski method is used to produce ultra-high purity GaAs for semi-insulators.
GaAs is often used a substrate material for the epitaxial growth of other III-V semiconductors including: InGaAs and GaInNAs.
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