How does a field-effect transistor (FET) work?

A field-effect transistor (FET) works by controlling the flow of current through a semiconductor channel.

A field-effect transistor (FET) is a type of transistor that uses an electric field to control the flow of current through a semiconductor channel. The FET consists of three terminals: the source, the drain, and the gate. The source and the drain are connected to the semiconductor channel, which is usually made of silicon. The gate is separated from the semiconductor channel by a thin insulating layer, usually made of silicon dioxide.

When a voltage is applied to the gate, an electric field is created in the insulating layer, which in turn creates an electric field in the semiconductor channel. This electric field controls the flow of current through the channel. When the voltage applied to the gate is positive, it attracts electrons from the semiconductor channel, creating a depletion region near the gate. This depletion region reduces the flow of current through the channel. When the voltage applied to the gate is negative, it repels electrons from the semiconductor channel, creating an inversion layer near the gate. This inversion layer increases the flow of current through the channel.

FETs have several advantages over other types of transistors, including high input impedance, low noise, and low power consumption. They are commonly used in amplifiers, switches, and digital circuits.