Dresden 2020 – scientific programme

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DS: Fachverband Dünne Schichten

DS 42: Focus Session: Functional Metal Oxides for Novel Applications and Devices III (joint session HL/DS)

DS 42.5: Talk

Thursday, March 19, 2020, 16:00–16:15, POT 81

Electric and Thermoelectric Properties of ZnGa₂O₄ Bulk Crystals — •Johannes Boy¹, Martin Handwerg¹, Rüdiger Mitdank¹, Zbigniew Galazka², and Saskia F. Fischer¹ — ¹Novel Materials Group, Humboldt-Universität zu Berlin, Newtonstraße 15, 12489 Berlin, Germany — ²Leibniz Institute for Crystal Growth, Max-Born-Strasse 2, 12489 Berlin, Germany

In the past years, intense research has been done in the field of oxide semiconductor materials, which are promising candidates for the design of novel high power devices, optoelectronics and sensing systems due to their wide bandgap. ZnGa₂O₄ is a transparent material of blue coloration, with a high bandgap E_g=4.6 eV at room temperature [1]. The majority charge carrier type is n-type. Electron mobilities up to 100 cm²/Vs with charge carrier concentrations in the order of 10¹⁸ - 10¹⁹ cm⁻³ have been reported [1]. In this work, we manufactured microlabs on the chip [2] to investigate the temperature dependence of the Seebeck coefficient S, Hall charge carrier density n and mobility µ between T=10 K and T=320 K. At high bath temperatures T>230 K, the scattering is determined by electron-phonon-interaction. At low bath temperatures (between 10 and 150 K) we observe a temperature-independent maximum, which can be explained by electrons interacting with ionized impurities. The room temperature Seebeck coefficient is S_{(300 K)}=(−120±3) µV/K and decreases with decreasing bath temperature.[1] Z. Galazka, et al.; APL Materials 7, 022512 (2019).
[2] J. Boy, et al.; APL Materials 7, 022526 (2019).