SKM 2023 – wissenschaftliches Programm
HL 41.4: Vortrag
Donnerstag, 30. März 2023, 15:45–16:00, POT 81
Anisotropic IR active phonon modes and fundamental direct band-to-band transitions in α-(AlxGa1−x)2O3 alloys grown by MOCVD — •Elias Kluth1, A F M Anhar Uddin Bhuiyan2, Lingyu Meng2, Hongping Zhao2, Rüdiger Goldhahn1, and Martin Feneberg1 — 1Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Germany — 2Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio, USA
The corundum-like Ga2O3 polymorph α-Ga2O3 is of high research interest as it allows bandgap-engineering by alloying e.g. with α-Al2O3, α-In2O3, α-Ti2O3 and similar materials. Since the corundum-like crystal structure is anisotropic, a direction dependent investigation of the material properties is crucial. m-plane α-(AlxGa1−x)2O3 thin film samples up to x=0.76, grown on m-plane sapphire substrate by MOCVD have been investigated by infrared (IR) and visible-ultraviolet (UV) spectroscopic ellipsometry. IR ellipsometry yields the anisotropic IR active phonons and their shift to higher wavenumbers with increasing x. Furthermore, with UV ellipsometry, we find the anisotropic dielectric functions up to 6.6eV and the shift of the fundamental direct band-to-band transitions with increasing x. We report an anisotropic bowing parameter for α-(AlxGa1−x)2O3 of bord=2.7eV and bextra=2.5eV.