Preparation and characterization of high-Tc superconducting thin films with high critical current densities

The project was carried out in relation to possible cable and electronics applications of high-Tc materials. Laser ablation was used as the deposition technique because of its stoichiometry conservation. Films were made in the YBa2Cu3O7 compound due to its relatively simple stoichiometry compared to other High-Tc compounds. Much attention was paid to the critical current density. A very high critical current density was reached. By using texture analysis by X-ray diffraction, it was found that films with high critical current densities were epitaxial, while films with low critical current densities contained several crystalline orientations. Four techniques for patterning the films were used - photo lithography and wet etch, laser ablation lithography, laser writing and electron beam lithography and ion milling. Sub-micron patterning has been demonstrated without degradation of the superconducting properties. The achieved patterning resolution is sufficient for preparation of many superconducting components. (AB)