FRONT AND DOMAIN PROPAGATION IN SEMICONDUCTOR HETEROSTRUCTURES

We develop a theory of self-organized spatio-temporal structures arising in charge transport parallel to the layers of a modulation doped GaAs/AlxGa1-xAs heterostructure far from thermodynamic equilibrium. An applied electric field causes heating of the high-mobility electrons in the GaAs channel and real space transfer of hot electrons into the low-mobility AlxGa1-xAs layer. The time scale separation between fast real space transfer and slow dielectric relaxation leads to slow-fast behavior of the dynamic system, and to excitability of the medium. In the monostable and bistable regimes we predict the existence of stable solitary waves of the electric field and the carrier distribution using methods of singular perturbation theory. These correspond to travelling fronts, and to travelling field domains and pulses of real-space transferred electrons, respectively.