Dresden 2020 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 37: Focus Session: Functional Metal Oxides for Novel Applications and Devices II (joint session HL/DS)
DS 37.10: Vortrag
Donnerstag, 19. März 2020, 12:45–13:00, POT 81
Band offsets at κ-([Al,In]xGa1−x)2O3/MgO interfaces — •Thorsten Schultz1,2, Max Kneiß3, Philipp Storm3, Daniel Splith3, Holger von Wenckstern3, Marius Grundmann3, and Norbert Koch1,2 — 1Humboldt-Universität zu Berlin, Institut für Physik, Berlin, Germany — 2Helmholtz-Zentrum für Energie und Materialien GmbH, Berlin, Germany — 3Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik, Leipzig, Germany
Conduction and valence band offsets are amongst the most crucial material parameters for semiconductor heterostructure device design. Due to its expected high spontaneous electrical polarization and the possibility of polarization doping at heterointerfaces, the metastable orthorhombic κ-phase of Ga2O3 and its indium and aluminum alloy systems are an interesting material class. We report on valence and conduction band offsets of κ-(AlxGa1−x)2O3 and κ-(InxGa1−x)2O3 thin films to MgO as reference dielectric by X-ray photoelectron spectroscopy. The determined band alignments reveal the formation of a type I heterojunction to MgO for all compositions with conduction band offsets of at least 1.4 eV, providing excellent electron confinement. We further found that the conduction band offsets in the alloy system are mainly determined by the evolution of the bandgaps. Therefore, tunable conduction band offsets of up to 1.1 eV within the alloy system allow for subniveau transition energies in corresponding quantum wells from the IR to the visible regime, which are promising for application in, e.g., quantum-well infrared photodetectors.