What is a MOSFET?

MOSFET (Metal Oxide Semiconductor Field Effect Transistor)

• MOS -> Metal (for Gate Material) + SiO2 (oxide for insulator) + Semiconductor (used for Substrate)
• FET -> Gate is turned on and off by the transistor with an electric field passing through the gate oxide.

**But generally, polysilicon with heavy doping of either n-type or p-type is used for gate material.

MOSFET is a 4-terminal device which are drain (D), source (S), gate (G), and body: also known as substrate (B). Based on the type of conducting channel, MOS structure can be categorized as:

• n-channel MOS (NMOS)
• p-channel MOS (PMOS)