Modeling of body factor and subthreshold swing in bulk metal oxide semiconductor field effect transistors in short-channel regime

A compact and empirical model of subthreshold swing S and body factor gamma is developed in bulk metal oxide semiconductor field effect transistor (MOSFET) in the short-channel regime. Although the relation between S and gamma is simply given as S = 60(l + gamma) in the long-channel regime, this relation no longer holds in the short-channel regime due to the short channel effect (SCE). The model is derived using the capacitance network model and by fitting analytical equations to two-dimensional device simulation results. It is confirmed that the model is valid not only at low drain voltage but also at high drain voltage considering the effect of drain-induced barrier lowering. This model is very effective in the design of variable threshold-voltage complementary metal oxide semiconductor (VTCMOS) circuits.