Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 38: Oxide Semiconductors II

HL 38.3: Talk

Thursday, March 21, 2024, 10:00–10:15, ER 325

Molecular beam epitaxy of ε/κ-Ga₂O₃ using In as a surfactant — •Alexander Karg, Alexander Hinz, Marco Schowalter, Niklas Krantz, Patrick Vogt, Stephan Figge, Andreas Rosenauer, and Martin Eickhoff — Institute of Solid State Physics, University of Bremen, Bremen, Germany

This study is focused on the metastable orthorhombic ε-Ga₂O₃, for which a high spontaneous polarization along the c-axis is predicted, thus making two-dimensional electron gases with high sheet carrier densities at heterointerfaces conceivable [1]. The initiation of the ε-Ga₂O₃ growth by MBE requires the use of additives like Sn, added under Ga metal-rich growth conditions [2].

We present a systematic investigation of the role of In as a surfactant for MBE-growth of ε-Ga₂O₃ [3]. Starting from an ε-Ga₂O₃ buffer layer, realized by initial deposition of an ultrathin SnO₂ layer on the c-Al₂O₃ substrate[4], we deposited ε-(In,Ga)₂O₃ layers with varied In flux. The structural properties, the surface morphology and the In concentration in the resulting ε-(In,Ga)₂O₃ layers were investigated by X-ray diffraction, atomic force microscopy and scanning transmission electron microscopy. Based on these results we discuss the role of In as a surfactant during growth of ε-Ga₂O₃. Additionally, we demonstrate the use of indium as a surfactant to realize ε-(In,Al,Ga)₂O₃ heterostructures with well-defined and sharp interfaces.

[1] Macchioni et al., Appl. Phys. Exp. 9, 041102 (2016). [2] Kracht et al., Phys. Rev. Appl. 8, 054002 (2017). [3] Karg et al., APL Mater. 11, 091114 (2023). [4] Karg et al., J. Appl. Phys. 132, 195304 (2022).

Keywords: Epitaxial Growth; Gallium Oxide; Surfactant; Oxide Semiconductors; Wide Band Gap Semiconductor