Fabrication and characteristics of vertically stacked NbCN/MgO/NbCN Josephson junctions with thin intermediate electrodes

Vertically stacked NbCN/MgO/NbCN Josephson junctions with thin intermediate electrodes (2 nm-11 nm) have been fabricated on a wafer in a computer-controlled sputtering. The tunneling characteristics of fabricated junctions have been evaluated as functions of the number of stacks and thickness of intermediate electrodes d. As a result, it has been found that the energy gap for intermediate electrodes reduced with d linearly depending on 1/d. The junction quality parameter R/sub SG//R/sub N/ gradually decreased with d.