Wigner-function based simulation of classic and ballistic transport in scaled DG-MOSFETs using the Monte Carlo method

Double-gate (DG) MOS transistor structures have been proposed to boost the performance of scaled-down logic devices and to overcome some of the most severe problems encountered in bulk MOS field-effect transistors. However, with channel lengths below 25 nm. the question of the importance of quantum effects in the lateral direction, such as source-to-drain tunneling, arises. Frequently, ballistic transport is assumed which allows the device to be simulated using pure quantum-mechanical approaches. However, with carrier mean free paths in the range of several nanometers, scattering-limited transport may still be dominant which can be assessed using the Monte Carlo method by accounting for quantum-correction methods. An approach accounting for both, quantum interference phenomena and scattering processes, is based on the Wigner equation augmented by the Boltzmann collision operator. This equation can be solved using the Monte Carlo method. We report on the enhancement of the Wigner Monte Carlo simulator described by Kosina et al. (2002) for the simulation of silicon-based devices. The algorithm for annihilation of numerical particles now takes into account the multi-valley band structure of silicon. As test devices we use double-gate MOSFETs with gate lengths of 60 nm, 25 nm, and 10 nm.