MOSFET

A type of FET (field-effect transistor). While a bipolar transistor controls the output current with the input current, an FET controls the output current with the input voltage. A MOSFET has a structure in which the gate electrode is separated from the semiconductor channel by a thin oxide insulating layer. It is called a MOSFET because it has a triple-layer gate structure consisting of metal (Metal), oxide (Oxid), and semiconductor (Semiconductor). Compared with junction-type FETs, MOSFETs are suitable for high-power and high-frequency applications. There are two types of MOSFETs: depletion type and enhancement type. In the depletion type, the drain current is at its maximum when the gate voltage is zero, and as voltage is applied in the reverse (negative) direction, the drain current decreases and eventually turns off. In contrast, in the enhancement type, when the gate voltage is zero, it is in the off state and the drain current is minimal, but as the gate voltage is applied, the drain current increases. Note that the only type of junction FET is the depletion type.