Thin-film synthesis of the high-T_c oxide superconductor YBa₂Cu₃O₇ by electron-beam codeposition

The successful synthesis of high-T_c YBa₂Cu₃O₇ films by means of electron-beam codeposition are reported. Several important growth parameters have been surveyed in a preliminary way. The substrates investigated include Al₂O₃, ZrO₂, MgO, and SrTiO₃, The films were characterized by resistivity measurements, x-ray diffraction, microprobe, and Rutherford backscattering analysis. Some TEM and critical current density studies were also carried out. The best results to date have been obtained on SrTiO₃ substrates with which polycrystalline epitaxial growth has been achieved. Resistive superconducting transitions with zero resistance at 89.5 K and a 2 K width have been observed in these films.