Current-voltage characteristic, stability, and self-sustained current oscillations in resonant-tunneling n-doped semiconductor superlattices

摘要

We review the statics and dynamics of electric-field domains on dopedsuperlattices within a discrete drift model. A complete analysis of theconstruction and stability of stationary field profiles having two domains iscarried out. As a consequence we determine the intervals of doping on whichself-sustained current oscillations may appear under dc voltage bias. We havealso studied the influence of doping, boundary condition and length of thesuperlattice on the self-sustained oscillations. Our study shows that there arebistability regions where either self-sustained current oscillations or steadystates are reached depending on the initial condition. For a wide biasinterval, the self-sustained oscillations are due to the formation, motion andrecycling of electric-field domain walls inside the superlattice. There arebiases (typically in the region of bistability) for which the strength of thehigh and low field domains changes periodically in time while the domain wallremains almost pinned on a few quantum wells.