Quasi-ballistic transport in nano-scale devices: Boundary layer, potential fluctuation, and Coulomb interaction

The singular nature of the Boltzmann transport equation leads to the boundary layer around the virtual source in nano-scale device structures. We show that the boundary layer is a key concept to understand the physical mechanism behind quasi-ballistic transport in nano-scale devices. The self-consistent 3D Monte Carlo device simulator is constructed by including accurately the full Coulomb interaction. It is shown that that the boundary condition for the electron distribution function plays an essential role to obtain the correct transport characteristics and that the Coulomb interaction is indeed a key ingredient for reliable predictions of device properties.