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.
@article{arxiv.2407.16227,
title = {alpha-Ta Films on c-plane Sapphire with Enhanced Microstructure},
author = {Lena N. Majer and Sander Smink and Wolfgang Braun and Bernhard Fenk and Varun Harbola and Benjamin Stuhlhofer and Hongguang Wang and Peter A. van Aken and Jochen Mannhart and Felix V. E. Hensling},
journal= {arXiv preprint arXiv:2407.16227},
year = {2024}
}