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HL: Fachverband Halbleiterphysik

HL 38: Oxide Semiconductors II

HL 38.7: Vortrag

Donnerstag, 21. März 2024, 11:15–11:30, ER 325

Phase-selective growth of κ- vs β-Ga₂O₃ and (In_xGa_1−x)₂O₃ by In-mediated metal exchange catalysis in plasma-assisted molecular beam epitaxy — •Andrea Ardenghi¹, Oliver Bierwagen¹, Jonas Lähnemann¹, Joe Kler², Andreas Falkenstein², Manfred Martin², and Piero Mazzolini³ — ¹Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, 10117 Berlin, Germany — ²Institute of Physical Chemistry, RWTH Aachen University, D-52056 Aachen, Germany — ³Department of Mathematical, Physical and Computer Sciences, University of Parma, Parco Area delle Scienze 7/A, 43124 Parma, Italy

Monoclinic β-Ga₂O₃ is an ultra-wide bandgap semiconductor (Eg ≈ 4.8 eV) that is attracting increasingly attention for power electronics applications. The metastable kappa polymorph (κ-Ga₂O₃), which shares a comparable bandgap, exhibits piezoelectric and potentially ferroelectric properties. In-incorporation into any polymorphs of Ga₂O₃ allows to lower their bandgap. In this work, we provide a guideline to achieve single phase κ-, β-Ga₂O₃ as well as their (In_xGa_1−x)₂O₃ alloys up to x = 0.14 and x = 0.17 respectively, using In-mediated metal exchange catalysis in plasma assisted molecular beam epitaxy (MEXCAT-MBE). The polymorph transition from κ to β is addressed, highlighting the role played by the thermal stability of the κ-Ga₂O₃. Additionally, we demonstrate the growth of (-201) β-Ga₂O₃ on c-Al₂O₃ at temperatures at least 100 ^∘C above those achievable with conventional non-catalyzed MBE.

Keywords: Gallium oxide; Molecular beam epitaxy; Polymorphism; Catalysis