EFFECTS OF DEPOSITION TEMPERATURE AND ANNEALING PROCESS ON THE SUPERCONDUCTING PROPERTIES OF YBA2CU3O7-X THIN-FILMS PREPARED BY METAL ORGANIC-CHEMICAL VAPOR-DEPOSITION

Abstract

Superconducting YBa2Cu3O7-x thin films were deposited on SrTiO3 (100) single crystals by Metal Organic Chemical Vapor Deposition (MOCVD) using Y(thd)3, Ba(thd)2 and Cu(thd)2 as source materials. The effects of the deposition temperature and the in situ annealing process on the epitaxy, superconducting phase and oxidation state of the films were investigated and related to the superconducting transition temperature and the critical current density. The experimental results showed that the fraction of grains with a-b plane parallel to the substrate surface, increased as the deposition temperature increased and the cooling rate decreased. The critical temperature and critical current density of the films decreased as the deposition temperature decreased, whereas the oxygen stoichiometries of the films were close to 7 (orthorhombic structure) regardless of the deposition temperature. Therefore, it is suggested that the deterioration of superconducting properties of the films with decreasing deposition temperature is not owing to insufficient oxidation of the superconducting phase but owing to incomplete superconducting phase formation.