NEW CURRENT-DEFINED THRESHOLD VOLTAGE MODEL FROM 2D POTENTIAL DISTRIBUTION CALCULATIONS IN MOSFETS

A new method is presented to calculate analytically the threshold volt age (V-T). A perfect match between theory and experiment can be obtain ed using a ''current''-definition instead of a ''voltage''-definition for the V-T. A method to calculate analytically from the Poisson equat ion the two-dimensional potential distribution profile in CMOS devices is provided and applied to the Ground Plane nMOSFET. Using this poten tial, a new expression for the subthreshold current is derived from wh ich the V-T is calculated. The method is capable of handling long as w ell as small geometry devices. For the V-T roll-off good agreement wit h experimental data is achieved for channel lengths down to 0.1 mu m w ithout using fitting parameters.