Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 95: Poster IV B (Quantum dots and wires: Prepration, characterization, optical properties, and transport)
HL 95.27: Poster
Donnerstag, 19. März 2015, 14:00–20:00, Poster B
Determination of the inelastic diffusion length in GaAs/AlGaAs heterostructures by hot electron thermopower — •Oliver Kreiter1, Ulrich Wieser1, Arne Ludwig2, Andreas Dirk Wieck2, and Ulrich Kunze1 — 1Lehrstuhl für Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum, D-44780 Bochum, Germany — 2Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum, Germany
Precise determination of material parameters such as the charge carrier scattering length gain a growing interest in theoretical modelling of nanostructures for reliably predicting the appropriate device characteristics. On GaAs/AlGaAs (electron density n=3.04 · 1011 cm−2, mobility µ = 7.70 · 105 cm2(Vs)−1 at 4.2 K), we measured hot-electron thermopower (HETP) in quantum point contacts (QPCs). The sample consists of a symmetric cross junction of 600 nm wide channels, one supplied by a heating current and the other equipped with a series of split-gate contacts forming QPCs at distances ranging from 625 nm to several microns. We recorded the HETP signal at fixed heating current while one of the QPCs is tuned from positive gate voltages into pinch-off and all the others are kept open. At T = 4.2 K apart from quantum oscillations reflecting the QPC subband structure the HETP signal exhibits a maximum close to the threshold voltage. From the exponential decay of this maximum as a function of distance we extract the inelastic diffusion length. At temperatures above 10 K this length rapidly decreases due to lattice vibrations.