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

摘要

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 1K.