Anomalous misfit strain relaxation in ultrathin YBa sub 2 Cu sub 3 O sub 7 minus. delta. epitaxial films

Journal Article · Fri Mar 15 00:00:00 EST 1991 · Journal of Applied Physics; (USA)

DOI:https://doi.org/10.1063/1.348513· OSTI ID:5638295

Kamigaki, K; Terauchi, H ^[1]; Terashima, T; Bando, Y ^[2]; Iijima, K; Yamamoto, K; Hirata, K; Hayashi, K ^[3]; Nakagawa, I; Tomii, Y ^[4]

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1. Faculty of Science, Kwansei-Gakuin University, Nishinomiya 662, Japan (JP)
2. Institute for Chemical Research, Kyoto University, Uji 611 (Japan)
3. Research Institute for Production Development, Kyoto 606, (Japan)
4. Metal Science and Technology, Faculty of Engineering, Kyoto University, Kyoto 606, (Japan)

Ultrathin YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} epitaxial films were successfully grown {ital in} {ital situ} on (001) SrTiO{sub 3} and MgO substrates by means of ozone-incorporating activated reactive evaporation. The x-ray-diffraction study was carefully examined to determine the structural properties of the grown films. Excellent crystallinity with no interfacial disorders was revealed by the appearance of the Laue oscillations. It was found that in a well lattice-matched YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/SrTiO{sub 3} system, the crystallinity was deteriorated due to defect introduction at the critical layer thickness {ital h}{sub {ital c}} ( {similar to} 130 {ital A}). Interestingly, also in a poorly lattice-matched YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/MgO system, excellent crystallinity was revealed even at above {ital h}{sub {ital c}} ( {lt} 24 {ital A}). This implies that an anomalous misfit relaxation process exists in the YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/MgO system. In such a system, no crystal imperfection of the MgO substrate caused by defect introduction was elucidated by the grazing incidence x-ray scattering, which indicated that the MgO substrate did not contribute to the anomalous misfit relaxation. The anomalous growth manner was also found in YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}/MgO according to surface morphology investigations. Below 40 {ital A}( {gt} {ital h}{sub {ital c}}), island nucleation growth was found. Above 40 A, it was observed that an atomically smooth surface was obtained and the crystallinity was simultaneously improved. It is suggested that YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} possesses an anomalous misfit relaxation mechanism, and that especially in the growth on MgO, it couples with the characteristic growth behavior at the initial stage.

• OSTI ID: 5638295
• Journal Information: Journal of Applied Physics; (USA), Vol. 69:6; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CRYSTAL STRUCTURE
COPPER OXIDES
THIN FILMS
STRAINS
YTTRIUM OXIDES
DISLOCATIONS
MICROSTRUCTURE
STRESS RELAXATION
SUBSTRATES
VACUUM EVAPORATION
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CHALCOGENIDES
COPPER COMPOUNDS
CRYSTAL DEFECTS
EVAPORATION
FILMS
LINE DEFECTS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
RELAXATION
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies