Electric potential and threshold voltage models for double-gate Schottky-barrier source/drain MOSFETs

The threshold voltage, V-th of a double-gate (DG) Schottky-barrier (SB) source/drain (S/D) metal-oxide-semiconductor field-effect transistor (MOSFET) has been investigated. An analytic expression for surface potential is obtained by using Gauss's law and solving Poisson's equation, the results of which are compared with simulations, and good agreement is observed. Based on the potential model, a new definition for V-th is developed, and an analytic expression for V-th is obtained, including quantum mechanical effects and SB lowering effect. We find that V-th is very sensitive to the silicon body thickness, t(si). For a device with a small t(si) ( < 3 nm), V-th increases dramatically with the reduction of t(si). V-th decreases with the increase of the back-gate oxide thickness, and with the increasing of the drain bias. All the results can be of great help to the ultra-large scale integrated-circuit (ULSI) designers. (C) 2011 Elsevier Ltd. All rights reserved.