Low-RF-Loss Superconductive Thin-Film Alloys
Abstract
Stripline resonators in conjunction with an automated RF setup were used to determine RF losses in films of Nb, NbN and Nb3Sn. Variation in the losses with frequency for some of these films seems to be associated with particulate contamination during deposition. However, measurements also indicate that if clean films can be deposited they could be used for very long delay lines (hundreds of nanoseconds) at temperature compatible with existing closed- cycle cryocoolers. High RF losses in Nb films deposited by ion beam sputtering have been shown to be associated with contamination from stainless steel sputtered from fixtures in the chamber. Nb shadow masks were used to collimate the beam and this eliminated the problem. Reactively sputtered films of NbN deposited in this system onto heated substrates have transition temperatures as high as 14 K. A series of thick film pastes selected for their good insulating properties were used to form insulating layers on NBN. Two of these pastes adhered well to the NbN. Interaction with the NbN seems to be confined to a layer of 100 A. Keywords: Nb shadow masks, Niobium, Niobium-tin, Nitride.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 31, 1985
- Accession Number
- ADA166876
Entities
People
- R. W. Ralston
Organizations
- Massachusetts Institute of Technology