alpha-Ta Films on c-plane Sapphire with Enhanced Microstructure

Lena N. Majer; Sander Smink; Wolfgang Braun; Bernhard Fenk; Varun Harbola; Benjamin Stuhlhofer; Hongguang Wang; Peter A. van Aken; Jochen Mannhart; Felix V. E. Hensling

arXiv · 2407.16227

alpha-Ta Films on c-plane Sapphire with Enhanced Microstructure

Lena N. Majer·Sander Smink·Wolfgang Braun·Bernhard Fenk·Varun Harbola·Benjamin Stuhlhofer·Hongguang Wang·Peter A. van Aken·Jochen Mannhart·Felix V. E. Hensling

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Abstract

Superconducting films of alpha-Ta are promising candidates for the fabrication of advanced superconducting qubits. However, alpha-Ta films suffer from many growth-induced structural inadequacies that negatively affect their performance. We have therefore explored a new synthesis method for alpha-Ta films which allows the growth of these films with unprecedented quality. Using this method, high quality alpha-Ta films are deposited at a comparably high substrate temperature of 1150 C. They are single-phase alpha-Ta and have a single out-of-plane (110) orientation. They consist of grains above 2 um that have one of three possible in-plane orientations. As shown by scanning transmission electron microscopy and electron energy loss studies the substrate-film interfaces are sharp with no observable intermixing. The obtained insights into the epitaxial growth of body-centered-cubic films on quasi-hexagonal substrates lay the basis for harnessing the high structural coherence of such films in various applications.

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Lena N. Majer, Sander Smink, Wolfgang Braun, Bernhard Fenk, Varun Harbola, Benjamin Stuhlhofer, Hongguang Wang, Peter A. van Aken, Jochen Mannhart, Felix V. E. Hensling. 2024-07-23. alpha-Ta Films on c-plane Sapphire with Enhanced Microstructure. https://arxiv.org/abs/2407.16227

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