High-frequency and below bandgap anisotropic dielectric constants in α-(AlxGa1-x)2O3 (0 ≤ x ≤ 1)

Matthew Hilfiker, Ufuk Kilic, Megan Stokey, Riena Jinno, Yongjin Cho, Huili Grace Xing, Debdeep Jena, Rafał Korlacki, Mathias Schubert

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


A Mueller matrix spectroscopic ellipsometry approach was used to investigate the anisotropic dielectric constants of corundum α-(AlxGa1−x)2O3 thin films in their below bandgap spectral regions. The sample set was epitaxially grown using plasma-assisted molecular beam epitaxy on m-plane sapphire. The spectroscopic ellipsometry measurements were performed at multiple azimuthal angles to resolve the uniaxial dielectric properties. A Cauchy dispersion model was applied, and high-frequency dielectric constants are determined for polarization perpendicular and parallel ∞ to the thin film c-axis. The optical birefringence is negative throughout the composition range, and the overall index of refraction substantially decreases upon incorporation of Al. We find small bowing parameters of the high-frequency dielectric constants with ⊥and 0.307.

Original languageEnglish (US)
Article number092103
Pages (from-to)1ENG
JournalApplied Physics Letters
Issue number9
StatePublished - Aug 30 2021

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)


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