  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.
