Dependence of critical temperature and resistivity of thin film Nb47wt%Ti on magnetron sputtering conditions

Niobium-titanium multilayers generally have depressed critical temperature, T-c. In this paper the variation of T-c and resistivity of magnetron sputt ered Nb47wt%Ti thin films is studied as a function of the cathode power and target usage. The data are compared with analyses by Auger and scanning el ectron microscopy. Films made using a new target have properties which are similar to those of bulk Nb47wt%Ti when high cathode power is used. The dat a indicate a transition in the morphology of the film as power increases, w hich affects the rate at which interstitial atoms are incorporated into the growing film. After the target lost similar to 50% of its mass and acquire d strong surface relief, bulk properties could not be obtained, because dep osition rates for a given cathode power were lower than before. A small Ti enrichment (3-5%) between the films and the target was found for both sets of films.