Impacts of effective oxide thickness on a symmetric double-gate MOSFET with 9-nm gate length are studied, using full quantum simulation. The simulations are based on a self-consistent solution of the two-dimensional(2D) Poisson equation and the Schr ¨odinger equation within the non-equilibrium Green’s function formalism. Oxide thickness and gate dielectric are investigated in terms of drain current, on-off current ratio, off current, sub-threshold swing, drain induced barrier lowering, transconductance, drain conductance, and voltage. Simulation results illustrate that we can improve the device performance by proper selection of the effective oxide thickness. Impacts of effective oxide thickness on a symmetric double-gate MOSFET with 9-nm gate length are studied, using full quantum simulation. The simulations are based on a self-consistent solution of the two-dimensional (2D) Poisson equation and the Schr ¨ odinger equation within the non-equilibrium Green’s function formalism. Oxide thickness and gate dielectric are investigated in terms of drain current, on-off current ratio, off current, sub-threshold swing, drain induced barrier lowering, transconductance, drain conductance, and voltage . Simulation results illustrate that we can improve the device performance by proper selection of the effective oxide thickness.