The Preparation of Thin Films of B-1 Structure Superconducting Ternary Compounds

NbN, a binary B-1 structure superconducting compound, has been successfully prepared in thin film form by a high-purity sputtering process [J. R. Gavaler, J. K. Hulm, M. A. Janocko, and C. K. Jones, J. Vac. Sci. Technol. 6, 177 (1969)]. In this paper, we report on the deposition of ternary compounds, based on NbN, using a similar technique. The inclusion of a third element, such as carbon, titanium, or zirconium into the NbN structure was accomplished by sputtering in an argon-nitrogen atmosphere from a two-element target. These targets were made either by hot pressing a powder mixture of the elements into a proper form or by welding together two metal sheets into a single unit. Superconducting transition temperatures of ≳ 17 K have been obtained in both Nb–C–N and Nb–TiN thin films by depositing these films at very high temperatures. However, critical current and field data measured at 4.2 K showed that the use of very high substrate temperatures also caused a deleterious effect on these properties.