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Nonlinear charge transport in semiconductor nanostructures
Semiconductors have been established as models for complex spatio-temporal dynamics. Our group has a long-standing experience in modelling nonlinear and chaotic spatio-temporal pattern formation of charge transport. At present we are investigating the following nanostructures, which are the main focus of current research in semiconductor technology:
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Semiconductor superlattices consist of a periodic sequence of alternating layers of two different materials with different band gaps. By applying a DC voltage, complex spatio-temporal dynamics of the electron distribution generated by the formation of electric field domains and self-generated current oscillations can be observed. We apply methods of chaos control on these oscillation by means of time delayed feedback.
Collaborations:
- Prof. Dr. A. Wacker
(Lunds Universitet, Schweden),
(Mikroelektronik Centret Lyngy, Dänemark): Quantentransporttheorie
- Prof. Dr. M. Fromhold (University of Nottingham, UK)
- Prof. Dr. L. Eaves
(University of Nottingham, UK): Experiment
- Prof. Dr. J. Kolodzey
(University of Delaware, USA): Hochfrequenzoszillationen (exp.)
- Prof. Dr. E. Gornik
(Institut für Festkörperelektronik TU Wien);
Transmission durch Übergitter (experimentell)
- Prof. Dr. K. F. Renk
(Universität Regensburg); Höchstfrequenz-Oszillationen (experimentell)
- Prof. Dr. A. Wacker
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Resonant tunneling structures, consist of a quantum well embedded between two potential barriers giving rise to bistable, Z-shaped current-voltage characteristics. Lateral pattern formation vertical to the current flow leads to complex chaotic scenarios of breathing current filaments as well as trigger fronts. In order to stabilize unstable spatio-temporal patterns we use methods of time delayed feedback.
Collaborations:
- Dr. P. Rodin
(Ioffe Physico-Technical Institute St. Petersburg, Russia): Schaltfronten
- Prof. Dr. S.W. Teitsworth
(Duke University, NC, USA); Laterale Musterbildung in
niederdimensionalen Halbleiterstrukturen (experimentell)
- Dr. P. Rodin
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where the carriers are fully confined. In many respects this resembles the situation in atomic physics, so that these structures can be considered as artificial atoms. Ensembles of self-assembled quantum dots embedded in a resonant tunneling structure exhibit strongly nonlinear transport behaviour (negatice differential conductivity) and unusual noise properties.
Collaborations: