STUDIES OF HIGH-TEMPERATURE SUPERCONDUCTING THIN-FILMS BY TRANSMISSION ELECTRON-MICROSCOPY

High temperature superconducting thin films have been studied by trans mission electron microscopy. Observations showed many superconducting and non-superconducting particles formed on the YBa2Cu3O7 (YBCO) thin films synthesized by pulsed laser deposition, which increased the surf ace microwave resistance of the film. However, if the deposition condi tions are selected properly, epitaxial single crystalline YBCO films c an be obtained. The effect of resputtering deviates the deposited film from stoichiometric composition for the DC magnetron sputtering. An o ff-axis sputtering configuration can compensate this shortcoming. The low T-c (similar to 98K) Tl2Ba2CaCu2O8 films showed many defects, but if the post annealing procedure is performed carefully, good quality T l-2212 thin films can be obtained.