Evaluating the Ballistic Transport in nFinFETs: A Carrier Centric Perspective

A 3D-TCAD Monte Carlo device simulator with real-space treatment of the electron-electron (e-e) and electron-ion (e-i) interactions is used to evaluate the role of these Coulomb interactions, surface roughness scattering, and phonon scattering mechanisms on the charge transport and the ballisticity of nFinFETs. A statistical analysis was performed, showing an increased dominance of phonon scattering mechanisms over surface roughness scattering as the channel length scales down. An analysis of the transit time of electrons in the device was also performed, and it serves as a basis to study how the carrier's energy evolves as they stay in the channel. The results show a significant widening of the carriers' energy distribution and a decrease in its average value as the carriers' time in the channel increases. Such behavior is attributed to the surface and phonon scattering mechanisms, and particularly to the e-e interactions. While the phonon scattering mechanisms take a long time to be effective, the e-e interactions dominate at short time scales, which is consistent with literature findings. The impact of short-range e-e interactions was also evaluated. Results show that their impact becomes more significant as carriers' transit time gets smaller in deeply scaled devices.