Enhanced suppression of superconductivity in amorphous films with nano-scale patterning

We have measured the thickness dependence of the superconducting critical temperature, T(c)(d(Bi)), in amorphous Bi/Sb films patterned with a regular array of holes as well as nanoscale thickness variations. We find that the mean field T(c) is suppressed relative to simultaneously produced unstructured films of the same thickness. Surprisingly, however, the functional form for T(c)(d(Bi)), remains unaffected. The role of the thickness variations in suppressing Tc is compared to the role of the holes, through parameterization of the surface. as measured through AFM/SEM and a proximity effect calculation. These results suggest that these two nanoscale modifications suppress T(c) about equally and are consistent with T(c) being determined on a microscopic length scale. (c) 2009 Elsevier B.V. All rights reserved.