Optimization Of Electrical And Structural Parameters Of Yba2cu3o7-X Thin-Film Bicrystal Josephson Junctions With Chemical And Thermal Treatments Of Substrates

The [100]-tilt high-T-c Josephson junctions are characterized by high characteristic voltages IcRn but their current range is limited by low critical currents I-cf of the thin-film electrodes with tilted c-axes. The impact of chemical and thermal treatments of NdGaO3 substrates on morphology and IV curves of the YBa2Cu3O7-x thin films and the bicrystal thin-film junctions have been studied. It was found that IV curves of the films above a critical current Icf are described by a power-law dependence V = V-0(I/I-cf - 1)(n), where I-cf, V-0 and n are dependent on the c-axis tilt of the film and treatment of the substrate. Critical current densities j(c)(78K) up to 1.4.10(7) A/cm(2) have been reached in 1.7 degrees-tilt YBa2Cu3O7-x films perpendicular to the tilt. Bicrystal junctions have been fabricated with optimized YBa2Cu3O7-x thin films, and RSJ-like IV-curves in the current ranges from I-c up to 5 I-c with IcRn (78K)-values of 1 mV have been achieved.