The metal semiconductor metal-effect transistor (MOSFET, MOS-FET or MOS FET) is a field-effect transistor type (FET).
It has an isolated gate whose voltage determines the conductivity of the device. This ability to change the conductivity with the amount of applied voltage can be used to amplify or switch the electronic signals. A semiconductor metal-insulated transistor type or MISFET is a term almost synonymous with MOSFET. Another synonym is IGFET for the isolated field effect transistor.
The basic principle of the field effect transistor was the first patented by Julius Edgar Lilienfeld in 1925.
The main advantage of a MOSFET is that it requires almost no input current to control the load current compared to bipolar transistors. In a “MOSFET mode” mode improvement, the voltage applied to the gate terminal increases the conductivity of the device. In the “exhaust mode” transistors, gate voltage reduces conductivity.
“Metal” in the MOSFET name is now often the wrong name because the gate material is often a layer of polysilicon (polycrystalline silicon). The “oxide” in the name can also be a wrong name, because different dielectric materials are used in order to obtain strong channels with lower applied voltages.
The MOSFET is by far the most common transistor in digital circuits because hundreds of thousands or millions of them can be included in a memory chip or microprocessor. Since MOSFETs can be made with p or n semiconductors, complementary pairs of MOS transistors can be used to make switching circuits with low power consumption in the form of a CMOS logic.