No abstract

In this paper we report on the possibility to use particle-based Monte Carlo techniques to incorporate all relevant quantum effects in the simulation of semiconductor nanotransistors. Starting from the conventional Monte Carlo approach within the semi-classical Boltzmann approximation, we develop a multi-subband description of transport to include quantization in ultra-thin body devices. This technique is then extended to the particle simulation of quantum transport within the Wigner formulation. This new simulator includes all expected quantum effects in nano-transistors and all relevant scattering mechanisms which are taken into account the same way as in Boltzmann simulation. This work is illustrated by analyzing the device operation and performance of multi-gate nano-transistors in a convenient range of channel lengths and thicknesses to separate the influence of all relevant effects: significant quantization effects occurs for thickness smaller than 5 nm and wave mechanical transport effects manifest themselves for channel length smaller than 10 nm. We also show that scattering mechanisms still have an important influence in nanoscaled double-gate transistors, both in the intrinsic part of the channel and in the resistive lateral extensions.

Based on Monte Carlo simulation, we report the study of the inversion layer mobility in n-channel strained Si/ Si 1-x Ge x MOS structures. The influence of the strain in the Si layer and of the doping level is studied. Universal mobility curves µ eff as a function of the effective vertical field E eff are obtained for various state of strain, as well as a fall-off of the mobility in weak inversion regime, which reproduces correctly the experimental trends. We also observe a mobility enhancement up to 120 % for strained Si/ Si 0.70 Ge 0.30 , in accordance with best experimental data. The effect of the strained Si channel thickness is also investigated: when decreasing the thickness, a mobility degradation is observed under low effective field only.