Analytic Oxide Capacitance Model of Double- and Surrounding-Gate Metal-Oxide-Semiconductor Field-Effect Transistors in Linear Region by Considering Inversion-Layer Capacitance

摘要

Inversion charge (Q_i) and oxide capacitance (C_(ox)~') of undoped (or lightly doped) or doped double-gate (DG) and surrounding-gate (SG) metal-oxide-semiconductor field-effect transistors (MOSFETs) with long channel were analytically modeled by considering inversion-layer capacitance (C_i) in linear region. The Q_(i) model of DG and SG MOSFETs was derived with a closed-form as a function of gate bias (V_(GS)), threshold voltage (V_(th)), and body structure factor (n) using one-dimensional (1D) Poisson's equation considering the mobile carrier. The n which reflects silicon body structure effect is 1 for DG MOSFETs and less than 1 for SG MOSFETs irrespective of channel doping (N_b). From the derived Q_(i), model considering the C_(i) effect, the C_(ox)~' was modeled and applied to the I_(d)-V_(gs) model of undoped or doped DG and SG MOSFETs in linear region. The compact current model using our proposed C_(ox)~' predicted more accurately the on-current behavior than that with the oxide capacitance (C_(ox)) in linear region.