Analytical models of subthreshold swing and threshold voltage for thin- and ultra-thin-film SOI MOSFETs

Analytical models are proposed for thin- and ultra-thin film silicon-on-insulator (SOI) MOSFETs operating in weak or strong inversion. The models take into account all the device parameters. The cases of two and three interfaces with a silicon substrate are considered in the modeling and compared with one another. These models give the main electrical MOSFET parameters in ohmic operation (subthreshold swing and threshold voltage) for these structures. The basic approximation is the consideration of a linearly varying potential in the Si film, which has been inferred on the basis of numerical simulations. Various behaviors depending on the Si film and the buried insulator thickness as well as the interface charges, Si film doping, or substrate regime are simulated to assess the properties and the performances of SOI MOS transistors and to validate the analytical models