SUB-100 NM LITHOGRAPHY AND HIGH-ASPECT-RATIO MASKS FOR FABRICATION OFJOSEPHSON DEVICES BY ION-IMPLANTATION

Freely positionable Josephson junctions in high-temperature supercondu ctor thin films are fabricated by a combination of conventional photol ithography and electron-beam lithography. In order to create weak-link s, point-defects in selected regions of YBa2Cu3O7-x, thin films were g enerated by 200 keV oxygen ion irradiation. In a temperature range jus t below the transition temperature T-c, all junctions can be described by the resistively shunted junction model. The magnetic modulation of the critical current on temperature clearly demonstrates SNS-behaviou r. Under microwave irradiation, Shapiro steps appear, and the dependen ce on microwave power reveals Josephson contributions ol er the entire temperature range.