Berlin 2012 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 44: Poster Session: Quantum Dots and Wires - Transport & Optical Properties

HL 44.4: Poster

Dienstag, 27. März 2012, 09:30–12:30, Poster D

Thermal white noise measurements of 2D and 1D electron gases — •Philipp Miechowski¹, Sven S. Buchholz¹, Dirk Reuter², Andreas D. Wieck², and Saskia F. Fischer¹ — ¹Neue Materialien, Humboldt-Universität zu Berlin, D-10099 Berlin — ²Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum

Electron-phonon interactions in semiconductors depend strongly on the lattice temperature, as thoroughly investigated in high-mobility 2D electron gases (2DEG) at temperatures below some 10 K. Open questions with respect to electron-phonon interactions remain for systems at the transition from 2D to 1D and suitable thermometry methods need to be established.
We apply thermal voltage noise measurements in the cross-correlation technique (0-20 kHz) [1]. For the setup calibration, we use discrete resistors. We make use of heating currents to create a temperature gradient over quasi-1D quantum structures. An improved measurement setup allows to eliminate noise contributions of the serial resistances caused by ohmic contacts and leads.
We investigate the influence of the lateral electronic confinement from 2D to 1D on the electron-phonon interaction and observe different temperature dependences for wide and narrow etched structures.
Noise thermometry proves to be an adequate instrument for the investigation of electron-phonon interactions in nano-structured semiconductors.

[1] S.S. Buchholz et.al., arxiv: 1111.1591 (2011).