A model for MOS effective channel mobility with emphasis in the subthreshold and transition region

In this work, the effects of surface potential fluctuations on the channel charge of a MOSFET are studied. By accounting for surface potential saturation, continuous models from below to above threshold are developed for the effective channel carrier concentration, the effective channel conductivity and, most importantly, the effective channel carrier mobility. The modeled mobility shows a dramatic drop-off around the threshold voltage, in agreement with experimental results. The equations developed herein may be used to improve the accuracy of existing transistor models for circuit simulation