Superconducting tantalum nitride-based normal metal-insulator-superconductor tunnel junctions

We report the development of superconducting tantalum nitride (TaN x ) normal metal-insulator-superconductor (NIS) tunnel junctions. For the insulating barrier, we used both AlO x and TaO x (Cu-AlO x -Al-TaN x and Cu-TaO x -TaN x ), with both devices exhibiting temperature dependent current-voltage characteristics which follow the simple one-particle tunneling model. The superconducting gap follows a BCS type temperature dependence, rendering these devices suitable for sensitive thermometry and bolometry from the superconducting transition temperature T C of the TaN x film at 5 K down to 0.5 K. Numerical simulations were also performed to predict how junction parameters should be tuned to achieve electronic cooling at temperatures above 1 K. V C 2014 AIP Publishing LLC .