Velocity distribution of electrons along the channel of nanoscale MOS transistors

In this paper, we discuss the evolution of electron velocity distribution along the channel of ultra short devices, using 2D self-consistent Monte-Carlo simulation. We confirm that injection in the channel obeys a thermionic injection mechanism. The presence of quasi ballistic electrons in the drain was found to reduce the potential drop in the drain access region and induce non ohmic properties at several nanometers. Finally, we stress for the first time the role of doping impurities from the drain contact as an ultimate limitation of electron injection velocity in the channel.