Quasi-ballistic, nonequilibrium electron distribution in inhomogeneous   semiconductor structures
  We report on a study of quasi-ballistic transport in deep submicron, inhomogeneous semiconductor structures, focusing on the analysis of signatures found in the full nonequilibrium electron distribution. We perform self-consistent numerical calculations of the Poisson-Boltzmann equations for a model n(+)-n(-)-n(+) GaAs structure and realistic, energy-dependent scattering. We show that, in general, the electron distribution displays significant, temperature dependent broadening and pronounced structure in the high-velocity tail of the distribution. The observed characteristics have a strong spatial dependence, related to the energy-dependence of the scattering, and the large inhomogeneous electric field variations in these systems. We show that in this quasi-ballistic regime, the high-velocity tail structure is due to pure ballistic transport, whereas the strong broadening is due to electron scattering within the channel, and at the source(drain) interfaces. 
D. Csontos and S. E. Ulloa (Department of Physics and Astronomy, Ohio   University)