Josephson bicrystal junctions on sapphire substrates for subMM waves receiver

This paper presents the results of fabrication and characterization of cuprate Josephson junctions on sapphire bicrystal substrates both at dc and sub mm waves. The Josephson junctions were fabricated on the r-cut sapphire bicrystal substrates consisting of two crystals for which the direction for both parts were misoriented at the angles±12° to the plane of interface. The YBCO was grown at T=750-770°C by dc sputtering at high oxygen pressure (4 mbar) after the CeO₂ epitaxial buffer layer magnetron sputtering at T=600-750°C and pressure 0.01mbar in an Ar/O₂ mixture. The amplitude-frequency characteristics (AFC) for the junction coupled with log-periodic antenna was obtained from the ratio of the detector and the Halley sell measured signals.