Properties of Y₁Ba₂Cu₃O7-x Superconducting Thin Films Prepared by Reactive Evaporation Method

The superconducting YBa 2 Cu 3 O 7- x (YBCO) thin films on MgO(100) substrates were prepared by a reactive evaporation method. Superconducting transition temperature and crystal quality were examined as a function of the substrate temperature ( T s ) and the oxygen partial pressure ( P O 2 ). The as-grown thin films at the substrate temperature of 620°C exhibited a zero resistance temperature ( T c zero ) of 83 K with the onset ( T c onset ) temperature of 88 K under the P O 2 of 2×10 -3 Torr. The lattice parameter c was about 11.74 Å for the as-grown film with T c zero of 80 K and was shortened to about 11.70 Å by the post-annealing at 900°C for 10 min in O 2 flow, although T c zero was not changed. This phenomena may be ascribed to the deficiency of oxygen in the CuO 2 plane of the YBCO layered perovskite structure.