Speaker
Description
Nb3Sn is a promising alternative to bulk niobium (Nb) for superconducting radio-frequency (SRF) cavities due to its higher critical temperature and superheating field. In this study, Nb3Sn thin films were deposited via DC magnetron sputtering from a stoichiometric Nb:Sn alloy target onto various substrates, including diamond-turned Cu, bulk Nb, and Cu with a Nb bilayer. The influence of magnetron power, film thickness and substrate on the surface resistance (Rs) at 7.8 GHz was systematically investigated.
Films deposited at lower magnetron powers (50 W) demonstrated significantly lower Rs values, reaching 0.38$\mu\Omega$ at 4.2 K, whereas higher power led to increased residual resistance, likely due to Cu diffusion and surface defects. Thinner Nb3Sn films exhibited elevated Rs while Nb3Sn films on bulk Nb showed variable performance depending on surface preparation, a film with a Nb bilayer on Cu unexpectedly underperformed relative to direct deposition on Cu.
Funding Agency
STFC
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