Regensburg 2019 – wissenschaftliches Programm
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  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 . 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 , 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.
 Chris Sturm et al., Phys. Rev. B 94, 035148 (2016)
 Maria B. Maccioni et al., Appl. Phys. Expr. 9, 041102 (2016)
 Max Kneiß et al., APL Materials, Accepted (2018)