MOSFETs

Power MOSFETs
A metal oxide semiconductor Field Effect Transistor (MOSFET) is combination of field effect concept and MOS technology.
The MOSFET is three terminal (gate, drain, source) four layer semiconductor device. MOSFET is a majority carrier device and as the majority carrier have no recombination delays, the MOSFET achieves extremely high bandwidths and switching times.
Working of Power MOSFETs
When gate is positive with respect to source an accumulation layer is formed in the layer channel as figure below. This accumulation layer is formed because of Vgs . The gate terminal(metal) is positive. The other side of oxide layer is p-type of body region.

Application of Power MOSFETs
(1) They are used in input amplifiers in oscilloscope and electronic voltmeters.
(2) They are used in logic circuits, for mixer operation of FM and TV receiver.
(3) They are used as voltage variable - resistors in computer memories.