Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 23: Oxide Semiconductors I

HL 23.9: Vortrag

Dienstag, 8. März 2016, 12:00–12:15, H13

Dielectric and Raman tensor of monoclinic Ga₂O₃ — •Chris Sturm¹, Christian Kranert¹, Jürgen Furthmüller², Friedhelm Bechstedt², Rüdiger Schmidt-Grund¹, and Marius Grundmann¹ — ¹Institut für Experimentelle Physik II, Universität Leipzig, Linnéstr. 5, 04103 Leipzig, Germany — ²Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena, Germany

Ga₂O₃ is a promising material for deep UV applications due to its band-gap energy of about 4.8 eV. At ambient conditions it crystalizes in a monoclinic structure and the dielectric function is a tensor consisting of 4 independent elements. The magnitude and dispersion of these elements were not known previously. We determined the full dielectric tensor in the spectral range of 0.5 − 8.5 eV by using generalized spectroscopic ellipsometry. The obtained DF is in excellent agreement with that obtained by many-body perturbation theory including quasiparticle and excitonic effects. This analysis yield that the off-diagonal element cannot be neglected in the entire investigated spectral range. Although this element seems to be negligible small in the transparent spectral range (|ε_xz | ≤ 0.02), it causes a rotation of the dielectric axis of about 20^∘. Using this DF we applied a new formalism for Raman scattering in anisotropic crystals to model the dependency of the Raman intensities on the scattering geometry for most phonon modes and determined the Raman tensor elements for these modes.

[1] C. Sturm et al., APL Mater. 3, 106106 (2015).