Dresden 2026 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 40: Oxide Semiconductors: Transport and Spectroscopy
HL 40.6: Vortrag
Donnerstag, 12. März 2026, 10:45–11:00, POT/0251
Bandgap, exciton dynamics, and anisotropic thermal transport in rutile-GeO2 — •Markus R. Wagner1,2, Luca S. M. Choi2, Nils Bernhard2, Pouria Emtenani2, Felix Nippert2, Moritz Meißner1, Hans Tornatzky1, and Zbigniew Galazka3 — 1Paul-Drude-Institut für Festkörperelektronik — 2Technische Universität Berlin, Institut für Physik und Astronomie — 3Leibniz-Institut für Kristallzüchtung
Rutile germanium dioxide (r-GeO2) is a promising ultra-wide bandgap material, predicted to support ambipolar doping and display high thermal and electronic conductivity, making it a strong candidate for power electronics. However, essential aspects of its properties, such as exciton and phonon dynamics as well as the role of defects and impurities, remain only partially explored. Here, we present our recent spectroscopic studies on r-GeO2. High-resolution spectroscopy of free exciton ground and excited states enables us to determine exciton binding energies and the temperature dependence of the bandgap. Polarization-resolved photoluminescence reveals pronounced differences between near-UV and visible emission bands, which we analyze regarding thermal quenching, recombination dynamics, and charge transfer through temperature- and power-dependent PL, TRPL, and PLE. Using time-domain thermoreflectance down to cryogenic temperatures, we establish the temperatur dependence of thermal conductivity and anisotropy, supported by Boltzmann transport calculations. Finally, polarization-resolved Raman spectroscopy identifies all first-order Raman-active phonons and their relative tensor elements.
Keywords: rutile GeO2; thermal transport; exciton binding energy; photoluminescence excitation spectroscopy; optical bandgap