In this paper, we present a one-dimensional (1D) simulation study of gate leakage current in metal insulator-metal (MIM) capacitors using the non-equilibrium Green's function (NEGF) formalism The simulation code has been used to calculate tunneling transmission probability and tunneling current through multi layer gate stacks with various high-pormittivity (high-kappa) dielectric materials Quantum-mechanical (NEGF) results are compared with the results of Wentzell-Kramers-Brillouin (WKB) classical approximation for different equivalent oxide thicknesses (EOTs) in numerous gate stacks such as single-SiO(2)-layer devices or double-layer (SiO(2) + high-kappa) structures. Quantum simulation shows that the conduction band offset between oxides induces wave-function reflections against barrier discontinuities, which significantly affect the transport of electrons and thus gate leakage current, particularly in double-layer high-A gate dielectric stacks The study of various high-kappa dielectrics also shows that gate leakage current strongly depends not only on material properties such as dielectric constant, effective mass, and conduction band offset, but also on interfacial oxide (SiO(2)) layer thickness. (C) 2009 The Japan Society of Applied Physics