Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 24: Thermal Properties
HL 24.2: Vortrag
Dienstag, 18. März 2025, 12:30–12:45, H14
Impact of AlGaAs interlayers on the thermal conductivity of GaAs micropillars — •Guillaume Würsch1, Ching-Wen Shih2, Mahmoud Elhajhasan1, Katharina Dudde1, Imad Limame2, Stefan Reitzenstein2, and Gordon Callsen1 — 1Institut für Festkörperphysik, Universität Bremen, Germany — 2Institut für Festkörperphysik, Technische Universität Berlin, Germany
First measurements of coherent heat conduction in semiconductor superlattices (SL) were reported over a decade ago. Interestingly, such an effect that is based on phonon interference can already be observed at room temperature, which sparks interest in measuring and controlling most fundamental phonon parameters like their mean free path lmfp and wavelength λtherm.Observing the effects of phonon interference in SLs can be challenging, because material stacks with superb crystalline quality and interfaces is required. In this work, we follow a step-by-step approach, meaning that we analyse GaAs micropillars (diameter: 0.5 - 2 µm) with a rising number (0 - 7) of Al0.8Ga0.2As interlayers. A thin layer of gold on top of these structures enables the measurement of the thermal conductivity κ via the frequency-domain thermal reflection (FDTR) technique, which is complementary to the Raman thermometry that we apply.Our study on first samples with a small numbers of interlayers provides not only insight into the thermal impact of each individual interface, but highlights the impact of the micropillar diameter. Building on such knowledge will allow us in future studies on larger SLs to disentangle phonon interference effects and phonon scattering phenomena.
Keywords: Thermal conductivity; GaAs; Phonons; Raman thermometry; Arsenides