Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 91: Poster Session: Quantum dots and wires: preparation & characterization & optical properties & transport properties
HL 91.29: Poster
Donnerstag, 14. März 2013, 16:00–20:00, Poster A
Thermal noise measurements of low-dimensional electron gases — •Christian Riha1, Philipp Miechowski1, Sven S. Buchholz1, Olivio Chiatti1, Dirk Reuter2, Andreas D. Wieck3, and Saskia F. Fischer1 — 1Neue Materialien, Humboldt-Universität zu Berlin, D-10099 Berlin — 2Optoelektronische Materialien und Bauelemente, Universität Paderborn, D-33098 Paderborn — 3Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum
Transport properties in low dimensional mesoscopic systems strongly differ from those of bulk material. We investigate the transport properties in 1D and 2D electron gases in the presence of temperature gradients. We apply Johnson noise thermometry to measure the spectral noise density in GaAs-AlGaAs heterostructures at temperatures below 10 K. The current heating technique allows us to create temperature gradients in 2D electron gases as well as in quantum point contacts. The cross-correlation technique and an improved measurement setup [1] enable a strong reduction of perturbation signals generated in ohmic contacts and leads. Non-local noise measurements on 1D electron gases at low temperatures have shown heat transport which is only carried by electrons. Our findings in local noise measurements differ from the expected Joule’s law due to an anomaly in thermal noise as a function of heating current. We observe time dependence of Johnson noise in structures that fulfill certain conditions. We present the results of systematic measurements and discuss possibilities of their physical origin.
[1] S.S. Buchholz et.al., Phys. Rev. B 85, 225301 (2012)