A systematic approach to reduce macroscopic defects in c-axis-oriented YBCO films

R. Krupke*, Z. Barkay, G. Deutscher

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

Abstract

c-axis-oriented YBCO films with Tc = 90 K and low macroscopic defect density were grown reproducibly on STO, LAO and YSZ/Al2O3 with a radio frequency (rf)-sputtering system using a pressure-controlled self-template (PST) process under optimized conditions. Hole formation in YBCO films was prevented and the target lifetime enhanced with a proper adjustment of the rf-power and the deliberate adding of H2O molecules to the sputtering gas. Variation of the oxygen pressure demonstrates that at low pressure, YBCO films with Tc = 85 K and a smoother surface are grown, while at high pressure, films with Tc = 90 K and a rough surface due to CuO particles are obtained. The benefits of both pressure regimes are merged in the PST process where the growth starts at low oxygen pressure. After the growth of a few unit cells, the pressure is increased and stabilized until the end of growth, resulting in YBCO films with Tc = 90 K and a significant smoother surface. We conclude that nucleation sites of CuO are located only on the substrate surface and that it is a necessity to grow YBCO in the stability region of CuO to obtain films with Tc = 90 K.

Original languageEnglish
Pages (from-to)536-539
Number of pages4
JournalPhysica C: Superconductivity and its Applications
Volume317-318
DOIs
StatePublished - 1999
EventProceedings of the 1998 1st Euroconference on Anomalous Complex Superconductors - Crete, Greece
Duration: 26 Sep 19983 Oct 1998

Keywords

  • Defect structure
  • Phase diagram
  • Sputter deposition
  • Template
  • Thin films

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