Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 45: HL Posters III

HL 45.48: Poster

Donnerstag, 4. April 2019, 18:30–21:00, Poster E

Optical phonon modes and dielectric function of orthorhombic κ-Ga2O3 thin films — •Andreas Müller, Chris Sturm, Max Kneiß, Vitaly Zviagin, and Marius Grundmann — Felix-Bloch-Institut für Festkörperphysik, Universität Leipzig, Linnéstraße 5, 04103 Leipzig

The large band gap energy of about 4.8  eV [1] makes Ga2O3 interesting as transparent conductive oxide. Of special interest is the orthorhombic κ-phase, due to its large predicted spontaneous electric polarization, which can be utilized for polarization doping to create high carrier densities at heterointerfaces [2]. However, the optical and phonon properties have not been explored in detail yet.

We determined the dielectric function of κ-Ga2O3 thin films, deposited by pulsed laser deposition on Al2O3, MgO and STO substrates [3], by means of spectroscopic ellipsometry from the infrared up to the ultraviolet spectral range (0.04 eV−8.50 eV). By means of a parametric model dielectric function approximation, the nature and the properties of the electronic band-to-band transitions as well as of the phonon modes were examined. Complementary to the investigations done by spectroscopic ellipsometry, we investigated the phonon modes by Raman spectroscopy and 8 phonon modes were identified.

[1] Chris Sturm et al., Phys. Rev. B 94, 035148 (2016)

[2] Maria B. Maccioni et al., Appl. Phys. Expr. 9, 041102 (2016)

[3] Max Kneiß et al., APL Materials, Accepted (2018)

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