Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 62: Focus Session: Functional Metal Oxides for Novel Applications and Devices II (joint session HL/DS)

HL 62.10: Talk

Thursday, March 19, 2020, 12:45–13:00, POT 81

Band offsets at κ-([Al,In]_xGa_1−x)₂O₃/MgO interfaces — •Thorsten Schultz^1,2, Max Kneiß³, Philipp Storm³, Daniel Splith³, Holger von Wenckstern³, Marius Grundmann³, and Norbert Koch^1,2 — 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-(Al_xGa_1−x)₂O₃ and κ-(In_xGa_1−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.