Nature of epitaxial growth of high- T sub c laser-deposited Y-Ba-Cu-O films on (100) strontium titanate substrates

Journal Article · Sun Apr 15 00:00:00 EDT 1990 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.345024· OSTI ID:6837581

Singh, R K; Narayan, J ^[1]

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1. Department of Materials Science, North Carolina State University, Raleigh, North Carolina 27696-7916 (USA) Engineering, North Carolina State University, Raleigh, North Carolina 27696-7916 (USA)

Epitaxial YBa{sub 2}Cu{sub 3}O{sub 7} films were fabricated on (100) SrTiO{sub 3} substrates by the pulsed laser ({lambda} =308 nm, {tau}=45{times}10{sup {minus}9} s) evaporation of bulk targets in a controlled oxygen atmosphere (partial pressure 100--600 mTorr). The nature of epitaxial growth and orientation of the film was controlled by the oxygen partial pressure in the chamber and the substrate temperature during the deposition process. These parameters were also important in determining the superconducting properties of the thin films. The best films exhibited zero electrical resistance at about 90 K with very high critical current densities. Thin single-crystal films were grown {ital in} {ital situ} at substrate temperatures greater than 550 {degree}C with the {ital c} axis perpendicular to the substrate, whereas films deposited at lower substrate temperatures showed a mixture of {ital c}- and {ital a} axes perpendicular to the substrate. The films deposited in high vacuum or low oxygen partial pressure ({lt}1 mTorr) and further annealed at high temperatures ({approx}900 {degree}C) in oxygen showed rectangular grains with the {ital c} axis parallel to the substrate. Higher-temperature ({gt}920 {degree}C) annealed films showed different surface morphology with the {ital c} axis perpendicular to the substrate. The epitaxial growth of YBa{sub 2}Cu{sub 3}O{sub 7} films on (100) SrTiO{sub 3} substrates is examined as a function of lattice mismatch between the thin film and the substrate. As the {ital a}{prime} and {ital c} axes of the tetragonal unit cell (above transformation temperature) of YBa{sub 2}Cu{sub 3}O{sub {ital x}} varies both with the temperature and the oxygen content, a new method is proposed to calculate the lattice parameters of the superconducting phase.

• OSTI ID: 6837581
• Journal Information: Journal of Applied Physics; (USA), Vol. 67:8; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
EPITAXY
COPPER OXIDES
YTTRIUM OXIDES
CRITICAL CURRENT
DEPOSITION
LASER RADIATION
LATTICE PARAMETERS
OXYGEN
PARTIAL PRESSURE
PULSES
STRONTIUM COMPOUNDS
SUBSTRATES
SUPERCONDUCTING FILMS
TITANATES
TRANSITION TEMPERATURE
VAPOR DEPOSITED COATINGS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COATINGS
COPPER COMPOUNDS
CURRENTS
ELECTRIC CURRENTS
ELECTROMAGNETIC RADIATION
ELEMENTS
FILMS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
RADIATIONS
THERMODYNAMIC PROPERTIES
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies