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Field-Effect Transistor (FET) ○꠹｜Definition｜1st｜20260419155516-00-⌔
Field-effect transistor - Wikipedia
Field-effect transistor
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.
FETs are also known as unipolar transistors since they involve single-carrier-type operation. That is, FETs use either electrons (n-channel) or holes (p-channel) as charge carriers in their operation, but not both. Field-effect transistors generally display very high input impedance at low frequencies. The most widely used field-effect transistor is the MOSFET, which became the most common type of transistor in computers, electronics, and communications technology due to its high scalability and low power consumption.
The concept of the FET was first proposed by Julius Edgar Lilienfeld in 1925 and by Oskar Heil in 1934, though neither was able to build a working device. The first successful FET, the junction field-effect transistor, was practically demonstrated in 1953. The MOSFET was later invented by Mohamed Atalla and Dawon Kahng at Bell Labs in 1960 and went on to become the foundation of modern integrated circuit technology.
FETs can be constructed from a variety of semiconductors, with silicon being by far the most common. More unusual materials include amorphous silicon, polycrystalline silicon, and organic semiconductors used in organic field-effect transistors (OFETs). Many distinct types of FETs exist, including the MOSFET, JFET, MESFET, HEMT, FinFET, and TFET, among others, each suited to different applications ranging from signal amplification to power control and biosensing.
FETs offer several advantages over bipolar junction transistors (BJTs), including very high input impedance, lower noise in sensitive electronics, excellent thermal stability, and extremely low power draw when switching. However, FETs also have disadvantages such as a relatively low gain–bandwidth product, susceptibility to overload voltages, and significant power dissipation during switching transitions.
Printed 2026-06-28.
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