Berlin 2015 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 34: Focussed Session: Oxide semiconductors I (joint session with HL)
DS 34.5: Vortrag
Donnerstag, 19. März 2015, 10:45–11:00, H 2032
Temperature-dependent thermal conductivity in Mg-doped and undoped β-Ga2O3 bulk-crystals — •Martin Handwerg1,2, Rüdiger Mitdank1, Zbigniew Galazka3, and and Saskia F. Fischer1 — 1AG Neue Materialien, Humboldt-Universität zu Berlin, 12489 Berlin, Germany — 2Helmholtz-Zentrum Berlin für Materialien und Energie GmbH,Hahn-Meitner-Platz 1, 14109 Berlin, Germany — 3Leibniz Institute for Crystal Growth, Max-Born-Strasse 2, 12489 Berlin, Germany
Transparent semiconducting insulators like Ga2O3 are important materials for high power electronics and optoelectronics.
For β-Ga2O3 only little information exist concerning the thermal properties, especially the thermal conductivity λ.
Here, the thermal conductivity is measured by applying the electrical 3ω-method on Czochralski-grown β-Ga2O3 bulk crystals, which have a thickness of 200 µ m and 800 µ m. At room temperature the thermal conductivity along the [100]-direction in Mg-doped electrical insulating and undoped semiconducting β-Ga2O3 is confirmed as 13± 1 Wm−1K−1 for both crystals [1]. The phonon contribution of λ dominates over the electron contribution below room temperature.
The observed function λ(T) is in accord with phonon-phonon-Umklapp scattering and the Debye-model for the specific heat at T 90 K which is about 0.1 fold of the Debye-temperature θD. Here a detailed discussion of the phonon-phonon-Umklapp scattering for T< θD is carried out. The influence of point defect scattering is considered for T<100 K.
[1] Martin Handwerg et al. , 2014, SST, accepted (arXiv 1407 4272)