In what application is gallium-arsenide used as a semiconductor material in preference to germanium or silicon?

Gallium-arsenide (GaAs) is a compound semiconductor prized for its incredibly high electron mobility. Electrons move through a GaAs crystal much faster than they do through silicon or germanium, which allows GaAs devices to switch states at extremely high speeds. This rapid switching capability makes GaAs the ideal semiconductor material for microwave frequency applications, such as satellite communications, radar, and cellular phone technology. At these ultra-high frequencies, standard silicon devices would suffer from excessive signal loss and poor performance. While silicon is generally preferred for low-frequency and high-power applications due to its lower cost and better thermal properties, gallium-arsenide excels where high-speed, high-frequency signal processing is mandatory.