Intrinsically shunted NbN/TaN/NbN Josephson junctions on Si substrates for large-scale integrated circuits applications

Superconducting circuits based on Josephson junctions have the potential to achieve high speed and ultra-low power consumption, but their integration is limited by the low controllability of Nb-based tunnel junction and the existence of shunt resistors. In this work, we report the fabrication of superconductor/normal metal/superconductor (SNS) Josephson junctions with high reproducibility on oxidized Si substrates. The junctions based on NbN/TaN/NbN trilayers measured at 4.2 K show excellent Josephson properties with a wide range of critical current (I (c)) from 227 to 2000 mu A. The variations of critical current density (J (c)) and characteristic voltage (V (c)) are respectively less than 7.1% and 7.5% in the 2 inch region. The standard deviation of I (c) is calculated to be less than 1.7% for Josephson arrays with the number of junctions up to 10 000 occupying an area of 0.34 mm(2). The results provide a guarantee for the applications of NbN-SNS Josephson junctions in superconducting large-scale integrated circuits.