Dresden 2026 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 26: Poster II

HL 26.40: Poster

Wednesday, March 11, 2026, 09:30–11:30, P1

Optical properties of (Ti_xGa_1−x)₂O₃ — •Leonard Käferstein, Clemens Petersen, Daniel Splith, Holger von Wenckstern, Chris Sturm, and Marius Grundmann — Felix Bloch Institute for Solid State Physics, Leipzig University, Leipzig, Germany

The high bandgap energy in the order of 5.3 eV and its high predicted electrical breakdown field of about 10 MV cm⁻¹ make α-Ga₂O₃ a quite promising material for transparent electronic devices and high power applications [1]. Alloying αGa₂O₃ with Ti leads to a decrease of the band gap. Here we report on the optical properties, especially the dielectric function, of (Ti_xGa_1−x)₂O₃ determined by spectroscopic ellipsometry as a function of the cation composition.

A (Ti_xGa_1−x)₂O₃ thin film with a lateral composition gradient was deposited by combinatorial pulsed laser deposition [2]. X-ray diffraction indicates a transformation from the tetragonal rutile phase for large Ti concentration (x > 0.55) toward a rhombohedral phase for x < 0.4. As (Ti_xGa_1−x)₂O₃ is optically uniaxial and the optic axis is within the surface plane, generalized spectroscopic ellipsometry was applied. In the transparent spectral range, we determined a decrease from positive birefringence for high x towards negative birefringence for x ≈ 0. As expected, we observe a redshift of the bandgap energy with increasing Ti-content from 5.1  eV for x ≈ 0 down to 4.3  eV for x ≈ 0.85.

[1] M. Higashiwaki et al., Appl. Phys. Lett. 100, 013504 (2012).

[2] H. v. Wenckstern et al., Ph. Status Solidi B 257, 1900626 (2020).

Keywords: Gallium oxide; titanium gallium oxide alloys; spectroscopic ellipsometry; dielectric function