Regensburg 2025 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 39: Poster III
HL 39.14: Poster
Mittwoch, 19. März 2025, 15:00–18:00, P3
Optical properties of α-(CrxGa1−x)2O3 — •Dmitry Sayenko, Clemens Petersen, Jakob Seifert, Christiane Dethloff, Holger von Wenckstern, Chris Sturm, and Marius Grundmann — Felix Bloch Institute for Solid State Physics, Leipzig University, Leipzig, Germany
Due to its high bandgap energy in the order of 4.6 − 5.0 eV and its high predicted electrical breakdown field of about 8 MV cm−1, Ga2O3 is a promising material for transparent electronic devices and high power applications [1]. Of special interest is the corundum-structured α-phase as it has the largest band gap energy of the Ga2O3 polymorphs. Further, its band gap energy can be tuned by alloying with Cr without changing its crystal structure. Here we present the dielectric function of α-(CrxGa1−x)2O3 as a function of the cation composition. The sample was grown by combinatorial pulsed laser deposition. As expected, the onset of absorption increases with increasing Ga concentration from around 3.2 eV for x ≈ 0.74 to 4.2 eV for x ≈ 0.13. Whereas we observe for all concentrations a negative birefringence in the visible range, i.e. neo < no, the polarization of the energetically lowest transition changes with Cr concentration. For large Cr concentration the absorption sets in at first for light polarized perpendicular to the c-axis whereas for large Ga concentration the first absorption is observed for light parallel to the c-axis. This change of the polarizability leads to a decrease of the birefringence with decreasing Cr concentration, but neo < no holds for all x.
[1] M. Higashiwaki et al., Appl. Phys. Lett. 100, 013504 (2012).
Keywords: dielectric function; birefringence; Ga2O3; bandgap engineering