Modeling the subthreshold swing in MOSFET's

This letter reports on the bias-dependence of the inverse subthreshold slope or subthreshold swing in MOSFET's. It is shown by calculations and verified by experiments that the subthreshold swing varies with gate bias and exhibits a global minimum. The gate-source voltage for which minimum subthreshold swing is reached, is linearly related to the voltage at which moderate inversion starts. Influence of oxide thickness and temperature is investigated. The subthreshold swing is an important parameter in modeling the weak inversion regime, especially for high-gain analog applications, imaging circuits, and low-voltage applications. Based on calculations of the subthreshold swing, we propose a new model for the diffusion component of the drain leakage current in MOSFET's. The model accurately predicts the temperature dependence of the drain leakage current.