MODELING OF ULTRATHIN DOUBLE-GATE NMOS SOI TRANSISTORS/

An analytical model valid near and below threshold is derived for doub le-gate nMOS/SOI devices. The model is based on Poisson's equation, co ntaining both the doping impurity charges and the electron concentrati on. An original assumption of the constant difference between surface and mid-film potentials is successfully introduced. The model provides explicit expressions of the threshold voltage and threshold surface p otential, which may no longer be assumed to be pinned at the limit of strong inversion, and demonstrates the nearly ideal subthreshold slope of ultrathin double-gate SOI transistors. Very good agreement with nu merical simulations is observed. Throughout the paper we give an insig ht into weak inversion mechanisms occurring in thin double-gate struct ures.