Vapor annealing synthesis of non-epitaxial MgB2 films on glassy carbon

A. A. Baker, L. B.Bayu Aji, J. H. Bae, E. Stavrou, D. J. Steich, S. K. McCall, S. O. Kucheyev

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

We describe the fabrication and characterization of 25-800 nm thick MgB2 films on glassy carbon substrates by Mg vapor annealing of sputter-deposited amorphous B films. Results demonstrate a critical role of both the initial B film thickness and the temperature-time profile on the microstructure, elemental composition, and superconducting properties of the resultant MgB2 films. Films with thicknesses of 55 nm and below exhibit a smooth surface, with a roughness of 1.1 nm, while thicker films have surface morphology consisting of elongated nano-crystallites. The suppression of the superconducting transition temperature for thin films scales linearly with the oxygen impurity concentration and also correlates with the amount of lattice disorder probed by Raman scattering. The best results are obtained by a rapid (12 min) anneal at 850 °C with large temperature ramp and cooling rates of ∼540 °C min-1. Such fast processing suppresses the deleterious oxygen uptake.

Original languageEnglish
Article number055006
JournalSuperconductor Science and Technology
Volume31
Issue number5
DOIs
StatePublished - 29 Mar 2018
Externally publishedYes

Keywords

  • levitation
  • MgB
  • superconductivity
  • thin film

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