Regensburg 1998 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 46: POSTER II

DY 46.10: Poster

Donnerstag, 26. März 1998, 14:30–17:30, B

Dynamics of Front Propagation in a Bistable Semiconductor Medium with Global Constraints — •P. Rodin^1,2, M. Meixner¹, and E. Schöll ¹ — ¹Institut für Theoretische Physik, Technische Universität Berlin,10623 Berlin — ²Alexander von Humboldt fellow on leave of absence from Ioffe Institute, St.Petersburg, Russia

Multilayered bistable semiconductor structures nowadays attract attention as a prominent example of controllable solid-state-based active media which may have applications as synergetical hardware of neural computers. In this paper we demonstrate that for gate-driven pnpn-structures a global constraint related to the gate circuit allows for tuning between accelerated, decelerated and oscillating switching fronts. Our model consists of a reaction-diffusion equation with a non-polynomial local kinetic function describing the internal dynamics of the semiconductor structure and a global integral constraint associated with the external control circuit. Without global constraint the front propagates with a constant speed whose value and direction depends on the gate potential. With global constraint, the front dynamics experiences a feedback, which may be positive or negative depending on the type of global coupling. For positive load resistance in the control circuit the feedback is positive and leads to acceleration of the front propagation. Negative feedback occurs in the case of an active external circuit with negative resistivity and results in monotonic or oscillatory slowing down preceding the formation of a steady kink-like filamentary pattern.