High t_c superconducting thin films and devices made from yba₂cu₃o_y

Abstract

We have used both electron-beam vapor deposition and sputtering systems to deposit superconducting thin films of the compound YBa2Cu3Oy. In the e-beam deposition system the three metals are individually evaporated in an oxygen partial pressure while the sputtering system uses composite targets. After a high temperature furnace anneal in flowing oxygen these films can have transition temperatures as high as 91 K. The films in thicknesses ranging from 0.07 to several microns are deposited on a variety of substrates such as alumina, Si, MgO, zirconia and SrTiO3. The epitaxial films which are grown on polished SrTiO3 single crystals generally show the highest critical current density, around 107A/cm2 observed at 4 K. Device applications of these films such as SQUIDs and transmission lines will be discussed with particular reference to the processing and patterning techniques used in their fabrication. These techniques include photo-and e-beam lithography, ion implantation and milling and laser ablation. © 1988, SPIE.