FABRICATION AND PROPERTIES OF YBCO TUNNEL-JUNCTIONS BY ION-BEAM SPUTTERING

Au/SrTiO3/YBCO tunnel junctions were fabricated by ion beam sputtering . The electrode of YBCO and SrTiO3 barrier layer were deposited on MgO (100) substrate at 700 degrees C and 550 degrees C respectively. The electrodes of YBCO had a Tc of 70 similar to 80 K. SrTiO3/YBCO bilayer s have been examined by X-ray diffraction and the results show that bo th the YBCO and barrier layer were well oriented. The current-voltage (I-V) and dV/dI-V characteristics of the junctions were measured. In a pin hole free junction, the resistance dip, corresponding to the dens ity of states, was obtained at voltage of 22 mV.