Regensburg 2004 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 30: Postersitzung IV: Kritische Ph
änomene, Quantenstörstellen, niederdimensionale Systeme

TT 30.33: Poster

Donnerstag, 11. März 2004, 14:30–19:00, Poster A

Optical measurements of two-dimensional electron systems on helium films — •Andreas Faustein, Jörg Angrik, Jürgen Klier, and Paul Leiderer — Fachbereich Physik, Universität Konstanz, Postfach M676, D-78457 Konstanz

We measure, with optical methods, the two-dimensional electron system on helium films which are adsorbed on metallic substrates as van-der-Waals films. Using plasmon spectroscopy and ellipsometry we are able to measure the helium film thickness with a resolution of approximately one Angström. The electrostatic pressure of the electrons decreases the film thickness which allows us to determine the electron density in the range from about 10¹³ to 10¹⁵ m⁻². Our experiments show a surprisingly high stability of the electrons on thin helium films of about 30 nm thickness adsorbed on evaporated gold films. Therefore not only static, but also transport and mobility measurements become possible. We show first measurements to determine electron densities on a source, split-gate, and drain electrode structure, where a quasi-one-dimensional electron transport through a confining channel is realized.