Current conduction mechanisms through a Metal-Oxide-Semiconductor structure are characterized via Fowler-Nordheim (FN) plots. The extraction of the FN parameters like the electron/hole effective mass in oxide m(ox) and in semiconductor m(sc), the barrier height at the semiconductor-oxide interface phi(B), and the correction oxide voltage V-corr for a MOS structure is made using a vertical optimization process on the current density without any assumption about phi(B) or m(ox). An excellent agreement is obtained between the FN plots calculated with the FN parameters extracted using a vertical optimization process with the experimental one. (C) 2016 Elsevier Ltd. All rights reserved.