Surface reactions and long time stability of YBCO thin films
1993
Abstract The surfaces of c -axis oriented YBa 2 Cu 3 O 7−δ (YBCO) thin films prepared by DC-magnetron sputtering on SrTiO 3 (100) substrates were studied by means of X-ray photoelectron spectroscopy (XPS). The measurements were carried out subsequently during a period of a three-months-storage of the samples in ambient air as well as immediately after the film deposition without exposing the film surfaces to atmosphere. A chemical reaction with formation of hydroxides and carbonates on top of the film surface was observed in the case of the air-exposed samples. The thickness of this top layer was found to develop proportionally to the square root of time with a time constant of 0.1 nm/h 0.5 . Accompanying measurements of the critical temperature ( T c ) and the critical current density ( j c ) show that T c and j c of the films are normally not affected by the top layer formation and remain nearly unchanged over periods longer than eight months.
Keywords:
- Sputter deposition
- Critical point (thermodynamics)
- Thin film
- Sputtering
- Chemical reaction
- Nuclear magnetic resonance
- Physics
- Ageing
- Surface layer
- X-ray photoelectron spectroscopy
- Inorganic chemistry
- High-temperature superconductivity
- Analytical chemistry
- Condensed matter physics
- Deposition (law)
- Inorganic compound
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