A Simple Model of Negative Capacitance FET With Electrostatic Short Channel Effects

A simple model of negative capacitance (NC) MOSFETs is presented. The model treats 2-D electrostatic effects, and the ballistic to diffusive transport regimes. It shows quantitative agreement with numerical device simulations based on a self-consistent solution of the Poisson equation and quantum transport equation based on nonequilibrium Green's function formalism, for an NC MOSFET structure without an internal floating gate. The model can accurately describe the reverse drain-induced barrier lowering (DIBL) and negative output differential conductance (NDC) effects as the NC FETs scale down. With approximations valid at low power supply voltages, it is shown that the improvement of the subthreshold swing (SS) due to electrostatic short channel effects results in a linear increase of the reverse DIBL and NDC. For a modified NC MOSFET structure with an ultrathin quantum metallic layer contacted to the source, the SS, however, can be improved considerably with the reverse DIBL and NDC approximately unchanged.