Nonlinear quantum transport in semiconductors

Abstract

We present a density matrix formalism to study the nonlinearities introduced by an electric field in a bulk semiconductor. In the high-field regime, the energy gained inbetween collisions (intercollision field effect) as well as that gained during a collision (intracollisional field effect) becomes important. Also, the scattering rates become quite high, giving deviations from the well-known Fermi Golden Rule formulation of the scattering events. In the strong damping limit, we obtain an expression for collision width for deformation potential scattering by including the intracollisional field effect. In the limit of a strong intracollisional field effect the collision width may be suppressed, giving rise to the possibility of a ballistic transport. But, for energies appropriate to impact ionization in bulk samples of GaAs, the contribution of intracollisional field effect is negligible.