Dresden 2003 – scientific programme
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HL: Halbleiterphysik
HL 49: Poster II
HL 49.4: Poster
Thursday, March 27, 2003, 16:30–19:00, HSZ/P2
Relaxation oscillations in a quantum Hall device influenced by the dynamic breakdown hysteresis of the QHE — •A. Buß1, N.G. Kalugin1, B.E. Sagol1, Ch. Stellmach1, A. Hirsch1, G. Nachtwei1, and G. Hein2 — 1Institut für Technische Physik, Mendelsohnstr.2, D-38106 Braunschweig — 2Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig
We investigated an oscillator based on a quantum Hall Corbino device. Because of the bistable behaviour in the breakdown region we were able to use the Corbino device as a switch, which opens at a certain voltage Vmax and closes at a lower fixed voltage Vmin. Using a simple scheme, including a serial resistor and a parallel capacitor we measured relaxation oscillations in a certain working range of the applied voltage. We developed a model for the voltage dependent behaviour of the oscillation frequency.The amplitude of the oscillations was much bigger than the hysteresis we measured in DC-regime. Therefore, we investigated the frequency dependence of the hysteresis by using low frequencies (<1-1kHz), and found a strong increase of the upper hysteresis limit Vmax at low frequencies ( DC< f < 20-30Hz), whereas the lower limit Vmin remained almost constant. This observation is consistent with the assumption of a decrease of the hopping conductivity with increasing frequency, related to a corresponding reduction of the localization length. We applied this assumption within a hot-electron model to explain the dynamic hysteresis at the breakdown of the QHE.