High resolution transmission electron microscopy study of interface structures and growth defects in epitaxial Bi{sub 2}Sr{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 4+2{ital n}+{delta}} films on SrTiO{sub 3} and LaAlO{sub 3}

Journal Article · Tue Oct 01 00:00:00 EDT 1996 · Journal of Materials Research

DOI:https://doi.org/10.1557/JMR.1996.0305· OSTI ID:389278

Zakharov, N D; Hesse, D ^[1]; Auge, J; Roskos, H G; Kurz, H ^[2]; Hoffschulz, H; Dreen, J; Stahl, H; Guentherodt, G ^[3]

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1. Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle/Saale (Germany)
2. Institut fuer Halbleitertechnik II, RWTH Aachen, Templergraben 55, D-52056 Aachen (Germany)
3. 2. Physikalisches Institut, RWTH Aachen, Templergraben 55, D-52056 Aachen (Germany)

The defect structure of epitaxial, {ital c}-oriented Bi{sub 2}Sr{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 4+2{ital n}+{delta}} (BSCCO) thin films grown by dc-sputtering and layer-by-layer MBE on SrTiO{sub 3} and LaAlO{sub 3} single crystal substrates was investigated by high-resolution transmission electron microscopy (HRTEM). Particular emphasis was put on the structure of the film/substrate interface. The films grown by dc-sputtering show a rather perfect structure involving a regular stacking of the unit cells. In spite of this regularity, there are many defects, such as twins, chemical stacking faults, and precipitates, as well as interfacial dislocations accommodating the film/substrate lattice misfit. The MBE-grown films contain twins and interfacial dislocations, but most prominent are precipitates of various size and rather high number density. Composition and structure of the precipitates were analyzed. Interfacial dislocations were found to be located in the films at a distance of up to 3 nm from the film/substrate interface. The experiments showed that the quality of the film/substrate interface in MBE-grown films is considerably higher with respect to smoothness, sharpness and regularity, if the layer-by-layer MBE process starts with a Sr{endash}O layer instead of a Bi{endash}O layer. This observation is in correspondence to the observed interface structure of the dc-sputtered films, where the first film layer was a Sr{endash}O layer, not a Bi{endash}O layer, in spite of the films being sputtered from a composite target. A structure model of the Bi{sub 2}Sr{sub 2}Ca{sub {ital n}{minus}1}Cu{sub {ital n}}O{sub 4+2{ital n}+{delta}}/(100)SrTiO{sub 3} interface is proposed. The prolonged MBE process was shown to imply a chemical interaction between the SrTiO{sub 3} substrate and the growing film, resulting in the formation of Sr-rich phases in the near-interface substrate regions. {copyright} {ital 1996 Materials Research Society.}

• OSTI ID: 389278
• Journal Information: Journal of Materials Research, Vol. 11, Issue 10; Other Information: PBD: Oct 1996
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
HIGH-TC SUPERCONDUCTORS
SUPERCONDUCTING FILMS
INTERFACES
SUBSTRATES
BISMUTH OXIDES
STRONTIUM OXIDES
CALCIUM OXIDES
COPPER OXIDES
TITANIUM OXIDES
LANTHANUM OXIDES
ALUMINIUM OXIDES
SPUTTERING
MOLECULAR BEAM EPITAXY
CRYSTAL DEFECTS
PHASE STUDIES
CHEMICAL COMPOSITION
TRANSMISSION ELECTRON MICROSCOPY