I n s i t u processing of epitaxial Y-Ba-Cu-O high T c superconducting films on (100) SrTiO3 and (100) YS-ZrO2 substrates at 500–650 °C

Abstract

We report the formation of excellent quality epitaxial YBa₂Cu₃O₇ films on (100) SrTiO₃ and (100) ZrO₂ (yttria stabilized) substrates in the temperature range of 500–650 °C by XECl excimer laser ablation in a 0.2 Torr oxygen ambient. By applying a dc bias voltage of +300 V to an interposing ring, we were able to reduce the substrate temperatures from 650 to 500 °C for obtaining epitaxial films. The quality of the epitaxial films was found to decrease with temperature, particularly below 550 °C. The thickness of the superconducting films was varied from 500 to 5000 Å with superconducting transition temperatures T_c (zero resistance) varying from 87 to 90 K for 650 °C deposits. The critical current density J_c of films was found to vary linearly with temperature with values of (zero magnetic field at 77 K) 5.0×10⁶ and 1.0×10⁶ for films deposited at 650 °C on (100) SrTiO₃ and (100) yttria‐stabilized zirconia substrates, respectively. X‐ray diffraction, transmission electron microscopy, electron channeling patterns, and Rutherford backscattering (RBS)/channeling showed excellent epitaxial quality of films on both substrates with best values of minimum ion channeling yield of 3.5% on (100) SrTiO₃ substrates.