Microwave properties of superconducting tunnel structures based on refractory materials

The electrophysics and microwave properties of Niobium oxide-barrier tunnel junctions with critical current densities up to 10⁵A/cm²were studied. Millimeter wave mixing using strong nonlinearity of quasi-particle tunnelling curve is described. Nonhysteretic Josephson junctions obtained by the low inductance resistive shunting of the tunnel structures were investigated in the large frequency band. The frequency range where these junctions obey the resistively shunted junction model was determined. The shunted tunnel junctions have been shown to be suitable for various applications which require stable enough Josephson junctions with nonhysteretic I-V curve (IVC).