What is MOSFET (metal oxide semiconductor field effect transistor)?

The MOSFETis the abbreviation of metal oxide semiconductor field effect transistor. It has a three terminals are source, gate and drain just like JFET. The MOSFET is a voltage controlled field effect transistor that is different from junction field effect transistor (JFET). The gate terminal in MOSFET is insulated from the channel therefore sometimes MOSFET is also called as IGFET (Insulated Gate Field Effect Transistor). The MOSFET has a metal oxide gate electrode which is electrically insulated from the main semiconductor n-channel by a very thin layer of insulating material i.e. silicon dioxide, commonly called as glass. The MOSFET is a core of integrated circuit and it can be design and fabricated in a single chip because of its very small sizes. It is also acts like a voltage controlled resistor where the current flowing through the main channel between the drain and source is proportional to the input voltage.

There are two types, in which a MOSFET can function,

1. Enhancement type MOSFET.

When the gate voltage is negative with respect to source, the depletion type MOSFET operates with an enhancement mode is known as enhancement type MOSFET.

2. Depletion type MOSFET.

When the gate voltage is positive with respect to source and the MOSFET operates in depletion mode is known as depletion type MOSFET.