I. Introduction
The metal-oxide semiconductor field-effect transistor (MOSFET) is a four-terminal device. In addition to the drain, gate and source, there is a substrate, or body contact. Generally, for practical applications, the substrate is connected to the source terminal. The depletion n-MOSFET device is formed from a p-type substrate with physically implanted/thermally diffused n-type source, drain regions. The dielectric material covers the area between the source and drain to provide electrical isolation.