Energy gap measurement of nanostructured thin aluminium films for use in single Cooper-pair devices

Understand

Within the context of superconducting gap engineering, Al-\alox-Al tunnel junctions have been used to study the variation in superconducting gap, $\Delta$, with film thickness.

• Films of thickness 5, 7, 10 and 30 nm were used to form the small area superconductor-insulator-superconductor (SIS) tunnel junctions.
• In agreement with previous measurements we have observed an increase in the superconducting energy gap of aluminium with a decrease in film thickness.
• In addition, we find grain size in small area films with thickness \textbf{$\geq$} 10 nm has no appreciable effect on energy gap.