A gallium arsenide field-effect transistor (GaAsFET) is a specialized type of field-effect transistor ( FET ) that is used in amplifier circuits at very-high, ultra-high, and microwave radio frequencies. This spans the electromagnetic radiation spectrum from approximately 30 MHz up to the infrared band. The GaAsFET is known for its sensitivity, and especially for the fact that it generates very little internal noise. This is because gallium arsenide has exceptional carrier mobility. The electron s and hole s move through the semiconductor material easily and fast. The GaAsFET is a depletion-mode device. This means that it conducts when no voltage is applied to the control electrode (gate), and when a voltage appears at the gate, the channel conductivity decreases.
In weak-signal wireless communications and broadcast reception, GaAsFET devices perform better than most other types of FET. Some types of GaAsFET are used as radio-frequency ( RF ) power amplifiers. GaAsFETs are employed in space communications, in radio astronomy, and in experiments conducted by amateur radio operators.