An Observation of Quasi-Particle Tunneling Characteristics in All Y-Ba-Cu-O Thin Film Tunnel Junction
The first results are shown on the tunnel junction using high Tc superconducting oxide (Y-Ba-Cu-O) thin films for both base and counter electrodes. The tunnel junction with electrodes made of two crossing stripes of Y-Ba-Cu-O thin films was fabricated by an RF magnetron sputtering on an MgO substrate. A highly resistive thin barrier layer was prepared by p1asma-f1uorination of the surface of the Y-Ba-Cu-O base electrode prior to the deposition of the counter electrode.
A clear tunnel characteristic in an I–V curve with a well defined gap voltage and a small sub-gap leakage current was observed at 4.2K, although Josephson currents were not observed. The gap voltage was about 18mV at 4.2K, decreasing as the temperature was increased. The gap structure was observed up to 77K which was about the superconducting on-set temperature of the electrode films.
KeywordsJosephson Junction Tunnel Junction Oxide Superconductor Josephson Current Superconducting Film
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