Effect of annealing on the superconducting properties of a-NbxSi1-x thin films
Abstract
a-NbxSi1-x thin films with thicknesses down to 25 Å have been structurally characterized by transmission electron microscopy measurements. As-deposited or annealed films are shown to be continuous and homogeneous in composition and thickness, up to an annealing temperature of 500 ∘C. We have carried out low-temperature transport measurements on these films close to the superconductor-to-insulator transition (SIT) and shown a qualitative difference between the effect of annealing or composition and a reduction of the film thickness on the superconducting properties of a-NbSi. These results question the pertinence of the sheet resistance R□ as the relevant parameter to describe the SIT.