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

Niobium-titanium multilayers generally have depressed critical temperature, T/sub c/. In this paper the variation of T/sub c/ and resistivity of magnetron sputtered 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 electron 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 data indicate a transition in the morphology of the film as power increases, which affects the rate at which interstitial atoms are incorporated into the growing film. After the target lost /spl sim/50% of its mass and acquired strong surface relief, bulk properties could not be obtained, because deposition 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.