Regensburg 2000 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 46: POSTER II
DY 46.7: Poster
Donnerstag, 30. März 2000, 15:00–18:00, D
Microwave-induced patterns in n-GaAs — •V. Novák1, D. Mac Mathúna2, J. Hirschinger2, and W. Prettl2 — 1Institute of Physics AS CR, Cukrovarnická 10, 162 00 Prague — 2Institut für Experimentelle und Angewandte Physik, Universitätsstraße 31, 93053 Regensburg
Moderately doped semiconductors become almost insulating at temperature of liquid Helium due to the freeze-out of free carriers. If biased above certain critical voltage, the material exhibits an electric breakdown accompanied by the formation of current carrying filaments. Structures analogous to current filaments can be found, if a contactless sample of the material is subject to microwave electric field. Unlike the filaments the microwave-induced structures do not bear the enforced symmetry of the contacts. Instead, complex patterns can be observed to arise, depending on the frequency and the intensity of the microwave irradiation. Experiments have been carried out to determine the pattern forming mechanism, and a numerical model has been constructed, which reproduces some of the observed phenomena.