# MOSFET Calculator

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##### The n-type MOSFET is a four terminal semiconductor device. It consists of a p-type substrate with two n+ doped wells. For a p-type MOSFET, the dopings are n-type substrate and p+ wells. This calculator will calculate the current through two terminals of an n-type MOSFET. ##### The source contact is generally used as the voltage reference for the MOSFET. The gate region is a metal contact deposited over a thermally grown field oxide that insulates the gate metal from the channel region. The drain contact of the n-type MOSFET is connected to a positive voltage point called the drain voltage. ##### The gate metal contact forms a Metal Oxide Semiconductor contact with the substrate below the oxide insulator. When the voltage applied to the gate rises above the threshold of the MOS contact an inversion layer is created in the substrate and the once p-type semiconductor now has n-type properties. This inversion layer is referred to as the "channel" of the MOSFET. The ideal threshold voltage is determined by the equation: where is the surface potential to cause an inversion layer, NA is the semiconductor doping in the channel/substrate and Co is the capacitance of the oxide layer. The surface potential to cause an inversion layer, , is given by the equation  ##### Images taken from "Semiconductor Devices: Physics and Technology" 2nd Ed., S.M. Sze

 Gate Oxide Thickness (tox): Å Oxide Capacitance (Cox): F/cm2
 Channel Length (L): um Channel Width (Z): um Mobility (μ): cm2/V•s Gate Voltage Range(VG): V to V      Step Size:V Drain Voltage Range(VD): V to V Channel Doping (NB): 1/cm3
 Threshold Voltage (VT): V