Berlin 2018 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 10: Oxide Semiconductors for Novel Devices (Focussed Session): Session II
DS 10.9: Vortrag
Montag, 12. März 2018, 17:15–17:30, E 020
Thermal Conductivity of β-Ga2O3 Bulk and thin Films — •Martin Handwerg1, Robin Ahrling1, Rüdiger Mitdank1, Günter Wagner2, Zbigniew Galazka2, and Saskia F. Fischer1 — 1Novel Materials Group, Humboldt-Universität zu Berlin, 12489 Berlin, Germany — 2Leibniz Institute for Crystal Growth, 12489 Berlin, Germany
The transparent conductive oxide β-Ga2O3 is of huge interest for high power electronics and optoelectronics because of its high band gap (EG≈ 4.7 eV). Knowledge of the thermal conductivity is crucial to design stable applications.
Here, we investigate the thermal conductivity of thin MOVPE grown polycristalline β-Ga2O3 films on sapphire-substrates and
single-crystalline, electrically conductive β-Ga2O3 films on insulating Mg-doped Czochralski-grown β-Ga2O3 substrates.
In order to measure the thermal conductivity of films and substrates, we used multiple aspects of the 3ω-method: the differential 3ω-method with a separate measurement of the substrate; a variation of multiple heater lines with different line widths and a 2ω approach.
We observe a reduction of the bulk thermal conductivity in dependence of the crystallinity and film thickness.
This reduction can be explained with the reduced mean free path of the phonons due to the film thickness and grain sizes.
This result, as well as an observed electrical conductivity reduction with decreasing film thickness, leads to a limitation of thermally influenced applications with films thinner than ≈150 nm or the need of an improved thermal management.