Berlin 2018 – scientific programme
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DS: Fachverband Dünne Schichten
DS 13: Oxide Semiconductors for Novel Devices (Focussed Session): Session III
DS 13.4: Invited Talk
Tuesday, March 13, 2018, 11:00–11:30, E 020
Phonons and excitons in Ga2O3 polytypes — •Markus R. Wagner — Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin
We present a comparative experimental study of the optical, vibrational and thermal properties of Ga2O3 in the alpha-, beta-, gamma-, and epsilon-modification. The anisotropic band gap energies are probed by the observation of deep UV excitation channels using temperature-dependent, polychromatic photoluminescence excitation spectroscopy (PLE). Based on these experiments, we establish an order of the bandgap for the different polymorph of Ga2O3. In addition, we investigate the optical phonon modes of the different structural configurations of Ga2O3 by polarized and angular resolve micro-Raman spectroscopy. Finally, we compare the temperature-dependent thermal conductivity of the four different Ga2O3 polytypes as obtained by 3-omega measurements. The results are discussed considering phonon boundary scattering and size effects due to structural imperfections and reduced dimensionality in ultra-thin films.