Preparation method and rf behaviour of Nb3Sn thin films obtained by bronze process

Aiming to application in r.f. devices, a method to obtain Nb3Sn thin films, combining sputtering technique and bronze process, has been developed. A niobium film, 300-500 nm thick, is deposited by sputtering onto a 7 at. % tin bronze substratum. In order to allow the diffusion of tin into niobium and the formation of the A15 phase, the sample is maintained at about 700°C during the deposition, and for several hours after the deposition. A Nb3Sn film with very good adhesion on the substratum has been obtained. The rf behaviour of film has been analyzed at about 10 GHz at temperature near Tc, using a host copper cavity having the top plate substituted with the bronze-Nb3Sn sample. Both the quality factor and the frequency shift have been measured.