Phonons in Single-Domain κ-Ga2O3 Studied by Polarization Angle-Resolved Raman Scattering

Wüthrich A, Janzen BM, Gillen R, Tornatzky H, Ardenghi A, Bierwagen O, Sacchi A, Mazzolini P, Ries M, Ogawa T, Nishinaka H, Wagner MR (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Advanced Electronic Materials Wiley

DOI: 10.1002/aelm.202500497

Abstract

Gallium oxide (Ga2O3) is an ultra-wide bandgap semiconductor with several polymorphs, among which the orthorhombic κ-phase is particularly attractive for high-power electronics, non-volatile memory, and charge-tunable devices due to its large spontaneous polarization and potential ferroelectric behavior. However, commonly grown κ-Ga2O3 thin films contain nanoscale rotational domains, hindering the characterization of intrinsic properties and complicating device integration. In this work, we present the first combined experimental and theoretical Raman spectroscopy study of single-domain κ-Ga2O3 thin films grown on orthorhombic ε-GaFeO3 substrates. Using polarization- and angle-resolved Raman spectroscopy, we identify over 100 phonon modes, which correlate with 117 modes calculated via density functional perturbation theory. A systematic nomenclature is introduced based on mode symmetry and frequency to aid identification and comparison across future studies. Direct comparison with rotational-domain samples shows that single-domain films exhibit pronounced angle-dependent Raman intensities consistent with theoretical selection rules, features that are obscured in multi-domain films due to domain averaging. These findings establish polarization angle-resolved Raman spectroscopy as an effective alternative to XRD and TEM for domain structure analysis and provide a robust framework for further studies of κ-Ga2O3 in electronic applications.

Authors with CRIS profile

Roland Gillen Lehrstuhl für Experimentalphysik

Involved external institutions

Technische Universität Berlin DE Germany (DE) Forschungsverbund Berlin e.V. DE Germany (DE) University of Parma / Università degli Studi di Parma IT Italy (IT) Thermo Fisher Scientific Germany Limited & Co. KG DE Germany (DE) Kyoto Institute of Technology (KIT) / 京都工芸繊維大学 JP Japan (JP)

How to cite

APA:

Wüthrich, A., Janzen, B.M., Gillen, R., Tornatzky, H., Ardenghi, A., Bierwagen, O.,... Wagner, M.R. (2026). Phonons in Single-Domain κ-Ga2O3 Studied by Polarization Angle-Resolved Raman Scattering. Advanced Electronic Materials. https://doi.org/10.1002/aelm.202500497

MLA:

Wüthrich, Alwin, et al. "Phonons in Single-Domain κ-Ga2O3 Studied by Polarization Angle-Resolved Raman Scattering." Advanced Electronic Materials (2026).

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