2D Quantum Mechanical Simulation of Gate-Leakage Current in Double-Gate n-MOSFETs

The direct gate leakage current in double-gate n-type MOSFETs with physical gate lengths of 10 nm is investigated. This work uses a combination of a two-dimensional non-equilibrium Green´s function (NEGF) based upon a real-space expansion method and Poisson´s equation, which are solved self-consistently. In the conventional ID analysis of the gate leakage current, an optical potential or an imaginary energy has been necessary to broaden the energy level in the triangular quantum well for reduction of computational costs. It is found that, however, different from the results in the conventional ID analysis, peaks in the current density energy spectra, equivalently the energy levels, are broadened even under zero drain bias condition due to the quantum mechanical scatterings in the presence of the source and drain electrodes. This fact proves that the optical potential used in the conventional ID simulation merely models the effect of the existence of the electrodes and the 2D analysis gives more sound results.