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O: Fachverband Oberflächenphysik
O 48: Metal & Semiconductor substrates: Structure, epitaxy and growth
O 48.6: Vortrag
Dienstag, 10. März 2026, 15:45–16:00, HSZ/0204
Atomic structure of MBE-grown Ta-Ge alloy on Ge(001). — •Suhani Singh1, David Sommers1, Patrick Strohbeen2, Yi-Hsun Chen1, Javad Shabani2, Arkady Fedorov1, and Peter Jacobson1 — 1School of Mathematics and Physics, University of Queensland, St. Lucia, Queensland 4072, Australia — 2Center for Quantum Information Physics, Department of Physics, New York University, New York, New York 10003, USA
Tantalum-germanium (Ta-Ge) alloys are a promising option for superconducting devices.[1] Here, we study the atomic-scale structure and thermal evolution of an MBE-grown Ta-Ge alloy film on Ge(001) using scanning tunnelling microscopy (STM) and synchrotron-based soft x-ray photoemission (XPS). A series of annealing steps between 673 K and 873 K smoothed the initially corrugated surface and enabled atomic-resolution STM. Short anneals at 873 K, reveal three-fold symmetric surface domains. Longer anneals at 873 K led to the appearance of square lattice consistent with Ta(100), coexisting with more corrugated regions. Further temperature increase made the surface progressively rougher and difficult to image. Synchrotron-based XPS shows higher temperature annealing produces a Ge-rich surface, suggesting Ta migrates into the bulk. These preliminary results map out how thermal processing affects the Ta-Ge surface and will guide strategies to obtain cleaner, sharper superconductor-semiconductor interfaces.
[1] Patrick J Strohbeen et al. *Molecular beam epitaxy growth of superconducting tantalum germanide*. Applied Physics Letters 124, 9 (2024).
Keywords: Scanning tunnelling microscopy; Germanium; Tantalum; Superconductor; soft x-ray photoemission spectroscopy