Dresden 2020 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 30: Poster I

HL 30.11: Poster

Tuesday, March 17, 2020, 13:30–15:45, P3

Rectifying contacts to κ-Ga₂O₃ — •Max Kneiss, Anna Hassa, Peter Schlupp, Daniel Splith, Holger von Wenckstern, Michael Lorenz, and Marius Grundmann — Universität Leipzig, Felix-Bloch-Institut für Festkörperphysik

The orthorhombic κ-phase of Ga₂O₃ possesses a similarly high bandgap of  5 eV as the thermodynamically stable β-phase. Further, it is expected to exhibit a high spontaneous electrical polarization of 23 µC/cm² [1] that can be utilized for polarization doping in heterostructures to localize a 2DEG by polarization differences at interfaces which then can serve as active layer in device applications. To employ κ-Ga₂O₃ in devices such as UV- or quantum-well infrared photodetectors, the realization of rectifying contacts is a prerequisite. However, reports on such contacts to κ-Ga₂O₃ are rare. In this talk, we present sputtered PtO_x/Pt and PdO_x/Pd Schottky contacts to κ-Ga₂O₃ as well as PLD grown NiO/κ-Ga₂O₃ and ZnCo₂O₄/κ-Ga₂O₃ pn-heterojunctions. The κ-Ga₂O₃ thin films were grown epitaxially by PLD from tin-containing targets [2] on ZnO/ZnO:Al growth templates on a-sapphire. The Al-doped ZnO layer is needed as highly conductive current-spreading backcontact since lateral transport is suppressed in our κ-Ga₃O₃ thin films due to the presence of rotation domains. A Ti/Al/Au layer stack was employed as ohmic contact. By IV-measurements, we found rectifying behavior for all investigated types of contacts with rectification ratios of up to 8 orders of magnitude. [1] Maccioni et al., Appl. Phys. Expr. 9, 041102 (2016) [2] Kneiß et al., APL Materials 7, 022516 (2019)