Mobility degradation due to the gate field in the inversion layer of MOSFET's

A simple classical theory that explains how the carrier mobility degrades as a function of the gate field in the inversion layer of MOSFET's is presented here. A formula of effective gate field-dependent mobility is derived and is reducible to the well-known empirical formula at the limit of large gate oxide thickness. However, their difference becomes drastic at thin gate oxide and high gate fields. For example, attₒₓ = 200Å, andVGS = 5V, the difference is about 20% for mobility prediction if same physical parameters are used in both formulae. The present theory has been incorporated into a new model forI-Vcharacteristics of MOSFET's and good agreements with experimental data fortₒₓ = 200Å transistors have been observed.