High quality step-edge substrates for high- Tc superconducting devices

Despite the significant progress in fabrication methods of step edge, the lack of reproducibility still hinders their use in more complicated systems. To pursue the high reproducibility and quality of step edge for high- Tc superconducting devices, we have developed the technique to fabricate high quality step-edge substrates with arbitrary step angles. We used two steps to improve the step ramp quality substantially. The surface microscopy of step substrates shows high uniformity with respect to any step angle. There are no needles, waves, trenches, cascades, or other flaws on these surfaces. Serial Josephson junctions and superconducting quantum interference device arrays were fabricated onto step-edge substrates. The step-edge devices exhibit excellent results.