Characterization of electron transport at high fields in silicon-on-insulator devices: a Monte Carlo study

The high field transport regime of single gate (SG) SOI MOSFETs has been the subject of an in-depth characterization. To study this, we have used a Monte Carlo simulator where all the major features involved in the description of the transport of state-of-the-art SOI devices are taken into account: quantization, non-parabolic band structure, phonon and surface roughness scattering. It has been shown that the behaviour of stationary electron velocity curves versus the longitudinal electric field is different to what we found in standard bulk devices. Particularly, it is very interesting that different saturation velocity values show up in the simulations. We found different curves corresponding to different effective fields when both phonon and surface roughness scattering mechanisms are taken into consideration. In addition, it was observed that the electron velocity obtained was dependent on the silicon layer thickness even when the same effective field was taken into account. Clear dependence of the saturation velocity has also been depicted in the delta parameter (representing the abrupt variations of the oxide-semiconductor surface) used in the surface roughness scattering model. Finally, we have performed simulations on double gate (DG) MOSFETs and observed different saturation velocities when we change the thickness of the intrinsic silicon slab.