2025/12/07 by Pavolotsky, Alexey, Joint, François, Manjunatha, Udupa Sujit +6
#FOS: Physical sciences #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2512.06994
We report a Nb/Al-AlN /Nb superconducting tunnel junction process in which the AlN barrier is formed by plasma nitridation using a compact microwave electron-cyclotron-resonance (ECR) nitrogen plasma source integrated into a standard sputter cluster. This enables growth of uniform tunnel barriers across a broad range of specific resistances, with Rn A down to ≈ 3,Ω,μm2. Junctions maintain excellent quality, exhibiting Rj/Rn ≥ 25 at the highest barrier transparencies. We characterize resistivity, specific capacitance, and the evolution of junction parameters under room-temperature aging and thermal annealing. A consistent calibration of the junction specific capacitance Cs versus Rn A is established and independently validated by the performance of demonstrator SIS mixers designed using the extracted Cs.