SKM 2023 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 17: Optical Analysis of Thin Films III

DS 17.2: Hauptvortrag

Donnerstag, 30. März 2023, 16:45–17:15, SCH A 316

The physics of low symmetry semiconductors: Gallium oxide for the future of green energy as example — •Mathias Schubert — Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA — NanoLund and Solid State Physics, Lund University, 22100 Lund, Sweden

The physics of Gallium arsenide (zincblende structure) and Gallium nitride (wurtzite structure) led to disruptive technologies driven by extreme properties such as small effective mass, large direct bandgap, and piezoelectric polarization. Gallium reappears in a monoclinic crystal structure Oxide with enormous prospects for applications in power electronics for the future of green energy. Numerous new phenomena hitherto unknown for traditional semiconductors occur in monoclinic symmetry semiconductors such as non-parallel phonon-plasmon scattering, hyperbolic shear polaritons, splitting of associated transverse and longitudinal phonon modes, non-degenerate highly anisotropic fundamental excitonic band-to-band transitions, directional band offsets, and complex defect spin interactions within the highly anisotropic host lattice. The influences of composition, strain, doping, and defects are discussed for Gallium oxide and related alloys, and special emphasis is given to new semiconductor physics, and consequences for thin film growth and device designs are pointed out. Methods such as generalized ellipsometry, the optical Hall effect, Terahertz electron paramagnetic resonance ellipsometry, and density functional perturbation theory computations are employed for characterization and analysis.