Regensburg 2000 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 12: Poster I: Quanten Hall Effekt (1-9), II-VI Halbleiter (10-17), Epitaxie (18-23), Quantenpunkte und -dr
ähte (24-50), Photonik (51-59), Metall-Isolator Übergang (60-64), Si/Ge (65-67), Elektronentheorie (68-69), Amorphe Halbleiter, Ionen-Implantation
HL 12.4: Poster
Montag, 27. März 2000, 14:00–19:00, A
High Frequency Conductivity in the Quantum Hall Effect — •F. Hohls1, U. Zeitler1, R. J. Haug1, and K. Pierz2 — 1Inst. f. Festkörperphysik, Uni Hannover — 2PTB, Braunschweig
We have measured the ac-conductivity of a two dimensional electron
system (2DES) at the transition between integer quantum Hall
plateaus for frequencies from 100 kHz to 6 GHz. In addition we
measured the temperature dependence between 50 to 700 mK.
The 2DES is realized by a standard GaAs/AlGaAs heterostructure
and patterned into Corbino geometry.
The measured Shubnikov-de Haas (SdH) peaks
are analyzed for filling factors up to six. We show an analysis of
peak width and height and compare the frequency effects with the
temperature dependence.
We observe a dramatic increase of the peak value for frequencies
between 1 MHz and 1 GHz. While at low frequencies all SdH peaks
at different filling factors
show different values of conductivity (0.02 - 0.05 e2/h),
they converge at frequencies above 2 GHz to the same value of
0.17 e2/h. This value is three times smaller than the
theoretical predicted universal value of 0.5 e2/h. We
do not observe a similar converging peak value as function
of temperature though 700 mK compares to a photon energy of
15 GHz.