Niイオン打込み層を介したNbN/Pbジョセフソン素子の特性

概要

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Superconductor-Normal-Superconductor (SNS) Josephson junctions were fabricated by ion implantation. The base electrode, NbN was prepared by reactive sputtering. After the NbN film surface was cleaned by Ar^+ ion (5.4keV), Ni^+ ion (16.2keV) was implanted. The doses of ion bombard the junction region were in the range of 1×10^<16>∿1×10^<17> ions/cm^2 for Ar^+ ion and 0.5×10^<15>∿1×10^<16> ions/cm^2 for Ni^+ ion. The counterelectrode was Pb. Current-voltage characteristics of the junctions subjected to the microwave radiation were measured. The junctions exhibited the well-defined ac Josephson steps, the best of which can show microwave induced Josephson steps up to 0.6mV. The magnetic field dependence of the maximum dc Josephson current was measured and found to be simillar to that of dc SQUID.
山梨大学の論文