We fabricated epitaxial NbN/MgO/NbN Josephson tunnel junctions with good tunneling characteristics in the range of J_(C)=0.2-70 kA/cm~(2). The counter and base NbN electrodes of the tunnel junctions had the same T_(C) and 20 K resistivity at about 15.7 K and 60 μΩ-cm, respectively. X-ray analysis showed that all the layers that formed the tunnel junctions grew epitaxially. In the range of J_(C)=0.2-15 kA/cm~(2), the tunnel junctions fabricated had large gap voltages (5.6-5.9 mV), narrow gap widths (less than 0.1 mV), high I_(C)R_(N) products (2.6-3.8 mV), and small subgap leakage current (V_(m)=40-96 mV).
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