Hamburg 2001 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 7: Poster I
HL 7.55: Poster
Montag, 26. März 2001, 10:30–19:00, Rang S\ 3
Quantum Hall effect in a strongly disordered system — •M. Weiss1, A. G. M. Jansen1, S. S. Murzin2, and K. Eberl3 — 1Max Planck Institut für Festkörperforschung, Hochfeld Magnetlabor Grenoble, 25, rue des Martyrs - BP 166, 38042 Grenoble Cedex 9, France — 2Institute of Solid State Physics RAS, 142432, Chernogolovka, Moscow District, Russia — 3Max Planck Institut für Festkörperforschung, Postfach 800 665, 70569 Stuttgart, Germany
We report on magnetoresistance experiments on strongly disordered GaAs layers in magnetic fields up to 23 T and at temperatures down to 50 mK. The investigated samples are epitaxially grown, strongly Si-doped GaAs layers with thicknesses d between 30 and 140 nm.
The electron mobilities are around 2500 cm2/Vs. As the corresponding electronic mean free path of about 20 nm is considerably smaller than the layer thickness of the samples, the magnetoresistance data at 4.2 K are characteristic for a threedimensional system, showing one or two weak Shubnikov-de Haas oscillations and a linear Hall resistance. At the lowest temperatures, we observe an integer quantum Hall effect, which is most pronounced for samples with d around 50 nm, but persists up to layer thicknesses of 140 nm. Considering the behaviour of the phase coherence length LΦ at low temperatures, one has to state that the described samples fall into a transitional region between two- and three dimensions.