FRONT AND DOMAIN PROPAGATION IN SEMICONDUCTOR HETEROSTRUCTURES

We develop a theory of self-organized spatio-temporal structures arisi ng in charge transport parallel to the layers of a modulation doped Ga As/AlxGa1-xAs heterostructure far from thermodynamic equilibrium. An a pplied electric field causes heating of the high-mobility electrons in the GaAs channel and real space transfer of hot electrons into the lo w-mobility AlxGa1-xAs layer. The time scale separation between fast re al space transfer and slow dielectric relaxation leads to slow-fast be havior of the dynamic system, and to excitability of the medium. In th e monostable and bistable regimes we predict the existence of stable s olitary waves of the electric field and the carrier distribution using methods of singular perturbation theory. These correspond to travelli ng fronts, and to travelling field domains and pulses of real-space tr ansferred electrons, respectively.