Ion implantation for superconductor tape fabrication

#The present embodiments relate to superconducting materials and, more particularly, to superconductor tape fabrication.

#The synthesis of high temperature superconducting (HTS) devices such as HTS tapes involves many challenges including the need to form a complex stack of materials that constitute the HTS tape. In a conventional superconductor tape a superconductor layer is supported by a base layer that may be a steel material. A shunt metal layer or layers is formed on top of the superconductor layer on a side opposite the base layer to provide a current conduction path when a fault occurs. When a fault takes place in an SCFCL, due to the finite resistance acquired by the superconducting layer, current that is conducted almost exclusively through the superconductor layer under normal operation of the SCFCL is diverted into metallic layers that are in contact with the superconductor layer, which layers typically present lower resistance than the now-resistive superconductor layer. The current passing through the metallic layers during the fault condition may cause resistive heating that generates temperatures up to 200° C. or more in the HTS tape. As a result of high temperatures, roughening of metal surfaces as well as oxidation may take place in local spots or at a metal layer interface, leading to degradation of the metallic layers and reducing the lifetime of the HTS tape.

#On the other hand, in order to affect a significant voltage drop along the length of the superconductor tape, it may be desirable to increase the sheet resistance of the metallic layers in the HTS tape. Although this could in principle be accomplished by decreasing the thickness of a metal layer such as silver, the reduced thickness may lead to increased susceptibility to agglomeration or other degradation that may shorten the HTS tape lifetime. Accordingly, tailoring of properties of shunt metal layers in superconductor tapes in order to increase robustness may be desirable. It is with respect to these and other considerations that the present improvements are needed.

#FIG. 1A and FIG. 1B depict a top view of alternative ion implanters consistent with the present embodiments;

#FIGS. 1C and 1D depict a top view and end view, respectively, of an exemplary end station for implanting a tape;

#FIGS. 2A to 2B illustrate ion implantation of a superconductor tape according to an embodiment of the disclosure;

#The present embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which some embodiments are shown. The subject matter of the present disclosure, however, may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art. In the drawings, like numbers refer to like elements throughout.

#To address some of the deficiencies in the aforementioned superconductor tapes, embodiments are described herein that provide improved structure for superconductor tapes as well as improved techniques for forming superconductor tapes. These embodiments also provide improved devices that integrate a superconductor layer and metal layer in a stack of layers disposed on a substrate.

#To address fabrication issues of conventional superconductor tapes, the present embodiments in particular provide improved metal layers and techniques for forming metal layers for use in devices such as multilayer superconductor tapes. In various embodiments, ion implantation is used to process a metal layer in a device such as a superconductor tape to adjust properties of the metal layer including mechanical and thermal stability, as well as desired resistivity. In particular, the ion implantation may be used to create a metal alloy material in the metal layer that imparts a combination of desired properties for the metal layer.