Document Type

Conference Paper

Publication Date

2011

Publication Title

Proceedings of SRF 2011

Pages

819-825

Conference Name

SRF 2011, 25-29 July 2011, Chicago, Illinois

Abstract

An energetic condensation thin film coating technique with an electron cyclotron resonance (ECR) induced Niobium (Nb) plasma ion source is used to deposit Nb thin films on crystalline insulating substrates, such as a-plane and c-plane sapphire (Al₂O₃) and on magnesium oxide, MgO (100), (110), and (111).

Hetero-epitaxial Nb films were produced by ECR deposition with regulated substrate temperature. The residual resistivity ratio (RRR) of about 1 micron thick films on a-plane (1,1,-2,0) sapphire substrates reach values (350 - 450) comparable to high RRR bulk NB commonly used for SRF cavities.

The epitaxial relationship of Nb/crystalline substrate is found to be strongly influenced by the substrate bias voltage (added to the initial Nb+ kinetic energy, 64 eV), the substrate crystalline orientation, and heating conditions.

At low substrate temperature, the Nb films demonstrated non-epitaxial crystalline textures, revealed by XRD Pole Figure technique and Electron Backscattering Diffraction (EBSD). The texture might be caused by “Volmer-Weber” growth mode, i.e. island growth.

This study shows that the film’s crystal structural character has great impact on its RRR/Tc value.

Rights

© 2011 The Authors.

Published under the terms of the Creative Commons Attribution 3.0 Unported (CC BY 3.0) License.

Original Publication Citation

Zhao, X., Valente-Feliciano, A.-M., Spradlin, J. K., Phillips, H. L., Reece, C., Gu, D., Baumgart, H., Wu, A., & Seo, K. (2011). Structural characterization of Nb films deposited by ECR plasma energetic deposition on crystalline insulators. In Proceedings of SRF 2011 (pp. 819-825). JACOW. https://accelconf.web.cern.ch/SRF2011/papers/thpo044.pdf

ORCID

0000-0001-8272-2151 (Baumgart)

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