field-effect transistor

Cross-sectional view of a MOSFET type field-effect transistor, showing source, gate and drain terminals, and insulating oxide layer.

The field-effect transistor (FET) is a type of transistor that uses an electric field to control the current through a semiconductor. It comes in two types: junction FET (JFET) and metal–oxide–semiconductor FET (MOSFET). FETs have three terminals: source, gate, and drain. FETs control the current by the application of a voltage to the gate, which in turn alters the conductivity between the drain and source.