Compact Capacitance Model of Undoped or Lightly Doped Ultra-Scaled Triple-Gate FinFETs

A charge-based compact capacitance model has been developed describing the capacitance-voltage characteristics of undoped or lightly doped ultra-scaled triple-gate fin field-effect transistors. Based on a unified expression for the drain current and the inversion sheet charge density, i.e., the Ward-Dutton linear-charge-partition method and the drain current continuity principle, all trans-capacitances are analytically derived. The developed capacitance model is valid in all regions of operation, from the subthreshold region to the strong inversion region and from the linear region to the saturation region. The gate and source trans-capacitances have been validated by 3-D numerical simulations over a large range of device dimensions. The parameters of the capacitance model can be used to accurately predict the transfer and output characteristics of the transistors, making this compact model very useful for circuit designers.