Metal oxide semiconductor field effect transistor (MOSFET)

• The MOSFET stands for Metal Oxide Semiconductor Field Effect Transistor.
• It has a three terminal source, gate and drain terminals just like JFET.

MOSFET Symbol

• The gate terminal in MOSFET is insulated from the channel therefore sometimes MOSFET is also called as Insulated Gate Field Effect Transistor (IGFET).
• The MOSFET is a voltage controlled field effect transistor that is different from junction field effect transistor (JFET).
• 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.
• MOSFET 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.
• It is a core of integrated circuit and it can be design and fabricated in a single chip because of its very small sizes.

There are two types in which a MOSFET can function,

1. 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.

2. 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.