Smith chapter 1 problem 11, Gallium Arsenide

a) This material is a compound semiconductor, type III-V, because one element is from column IIIa and one is from Va on the periodic table.

b) Its electron mobility is about five or six times that of silicon, so transistors and circuits made of GaAs can switch much faster than those made of Si.

c) Its applications in the electronics industry are very high speed bipolar junction transistors and integrated circuits used in communications (radio & microwave frequencies, fiber optics internet backbone) where Si circuits are not fast enough. GaAs circuits can process signals up to about 100 GHz or so.

Note that GaAs cannot be made into MOS-FET type of transistors due to the lack of a clean gate dielectric with high dielectric strength.

Also note that the market for GaAs circuits is fairly small and specialized, perhaps 1/100 or 1/200 the size of the market for Si circuitry.

Bibliography: P.J.L. personal communication