SUPERCONDUCTIVITY IN AMORPHOUS TA GE MULTILAYERS/

This paper reports measurements of the superconducting transition temp erature (T-c) of Ta/Ge multilayers for a range of individual layer thi cknesses. Thick amorphous Ta layers which are isolated by thick insula ting (Ge) layers have a transition at 0.9 K, and it is noted that for thinner isolated layers T-c approaches zero as the resistance per squa re approaches the quantum resistance h/(2e)(2). However, the transitio n temperature is enhanced in samples with thin Ge layers, and in films with Ta layers thinner than 1.5 nm T-c rises to near 3 K. The enhance ment is consistent with a proximity effect involving layers of a Ta-Ga allow at the layer boundary.