TY - JOUR
T1 - A systematic approach to reduce macroscopic defects in c-axis-oriented YBCO films
AU - Krupke, R.
AU - Barkay, Z.
AU - Deutscher, G.
N1 - Funding Information:
This research was supported in part of the Heinrich Hertz Minerva-Center for High Temperature Superconductivity, of the Israel Science Foundation and of the Oren Family Chair for Experimental Solid State Physics.
PY - 1999
Y1 - 1999
N2 - 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.
AB - 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.
KW - Defect structure
KW - Phase diagram
KW - Sputter deposition
KW - Template
KW - Thin films
UR - http://www.scopus.com/inward/record.url?scp=0033133329&partnerID=8YFLogxK
U2 - 10.1016/S0921-4534(99)00119-7
DO - 10.1016/S0921-4534(99)00119-7
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AN - SCOPUS:0033133329
SN - 0921-4534
VL - 317-318
SP - 536
EP - 539
JO - Physica C: Superconductivity and its Applications
JF - Physica C: Superconductivity and its Applications
T2 - Proceedings of the 1998 1st Euroconference on Anomalous Complex Superconductors
Y2 - 26 September 1998 through 3 October 1998
ER -