Planar Josephson junctions fabricated by focused-ion beam

We have fabricated nano-scaled planar superconductor-insulator-superconduct or Josephson junctions using focused ion beam (FIB) with beam spot size sim ilar to 5nm To study the effectiveness of this fabrication technique and fo r the purpose of comparisons, a variety of samples have been made based on high temperature superconducting (HTS) YBa2Cu3O7-delta electrodes. The insu lators are either vacuum or silicon dioxide. The samples showed current-vol tage (IV) characteristics typical of a resistively shunted junction (RSJ). We will discuss various aspects of the processing methods and the. physical significance of the junction characteristics.