Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 29: Poster II
HL 29.98: Poster
Dienstag, 18. März 2025, 18:00–20:00, P1
Ballistic Phonon Transport in β-Ga2O3 — Rüdiger Mitdank1, Robin Ahrling1, Johannes Boy1, •Olivio Chiatti1, Andreas Popp3, Zbigniew Galazka3, and Saskia F. Fischer1,2 — 1Novel Materials Group, Humboldt-Universität zu Berlin, 10099 Berlin, Germany — 2Center for the Science of Materials Berlin, Humboldt-Universität zu Berlin, 12489 Berlin, Germany — 3Leibniz-Institut für Kristallzüchtung, 12489 Berlin, Germany
β-Ga2O3 is a transparent ultra-wide bandgap semiconductor of interest for deep UV-devices, gas sensors and high power electronic applications [1]. Due to its low room temperature thermal conductivity heat dissipation is a major challenge in electronic device design [2].
Here, we observe the cross-over from resistive to ballistic phonon transport [3]: The anisotropic thermal conductivity and the phonon mean free path (mfp) of monoclinic β-Ga2O3 single crystals and homoepitaxial films are determined by the 3ω-method for temperatures from 300 K down to 10 K. Above 80 K phonon-phonon-Umklapp scattering dominates the phonon mfp, and below point-defect scattering is observed. Ballistic phonon transport is observed below 20 K and boundary effects of the sample size become dominant. These findings open a route to harness the phonon-drag to enhance the thermoelectric functionality by controlling the electron and phonon interaction.
[1] Galazka et al., Semicond. Sci. Technol. 33, 113001 (2018)
[2] Handwerg et al., Semicond. Sci. Technol. 30, 024006 (2015); Semicond. Sci. Technol. 31, 125006 (2016)
[3] Ahrling et al., Phys. Rev. B 110, 085302 (2024)
Keywords: Gallium Oxide; Ballistic phonon transport; Thermal conductivity; Phonon scattering