A NEW APPROACH TO THE CURRENT VOLTAGE CHARACTERISTICS OF A MOS-TRANSISTOR

This paper introduces a new model for the current-voltage (IV) characteristics of the MOS-transistor covering the subthreshold region as well as the linear and saturation region. The model is based on capture and emission processes from localized acceptor (n-channel) or donor (p-channel) levels in the surface space charge region. In a MOS transistor these interactions causes a conductivity in the channel which is a function of the band bending due to the surface potential determined by the applied gate voltage. The same analytical expression is valid over the whole current range. By a simple numerical method the one-dimensional model (valid for low drain-source voltages) is extended to two dimensions covering the whole current-voltage range. Excellent agreement with experiment is obtained including subthreshold properties, the bending of the IV-curves in the linear region, the pinch-off effect in the saturation region and substrate bias properties. Examples are given showing the influences of important process parameters on the slopes of the subthreshold IV-curves and the shapes of the IV-curves in the linear and saturation regions.