New Current–Voltage Model for Surrounding-Gate Metal–Oxide–Semiconductor Field Effect Transistors

Abstract

On the basis of the current continuity equation and closed-form solutions of Poisson's equation, a new and continuous current–voltage (I–V) model that includes both doped and undoped Si bodies for surrounding-gate metal–oxide–semiconductor field effect transistors (MOSFETs) is developed. The continuous form of the I–V equation represents the entire drain current characteristics including all regions of MOSFET operation: linear, saturation and subthreshold. Compared with conventional charge-sheet approximation, this approach preserves physical volume-inversion phenomena and easily predicts drain current characteristics without assuming an empirical smoothing function for the correctness of piecewise approximation. It is shown that the I–V curves can be generated using this model and agree well with two-dimensional (2D) simulation results over various drain biases. This model gives the exact I–V prediction for surrounding-gate MOSFETs and can be used in SPICE simulation.