Analytical expressions are presented to model the behavior of the potential at the surface and the difference of potentials at the surface and at the center of the doped silicon layer as function of silicon layer impurity concentration, gate dielectric thickness, silicon layer thickness and applied voltages in double-gate MOSFETs that considers for the first time a doped silicon layer in a range of concentrations between 10(14) and 3 x 10(18) cm(-3). No fitting parameters are required. All the equations obtained for the potentials were validated using a rigorous numerical calculation for different doping concentrations, as well as for several double-gate structure dimensions and applied voltages. Calculation of the threshold voltage using the derived expressions was also validated with ATLAS simulations. The expressions presented in the paper can be used directly for modeling current and capacitance in doped double-gate MOSFET. (c) 2007 Elsevier Ltd. All rights reserved.