Publication Type:Journal Article
Source:Journal of Materials Research, Volume 6, Number 11, p.2264-2271 (1991)
Keywords:Crystals - Atomic Structure, Cubic Structure, Growth Interfaces, High temperature superconductors, Oxide superconductors, Oxides - Superconductivity, Perovskite structure, Superconducting Films - Interfaces, Yttrium barium copper oxides
We have examined the atomic structure of growth interfaces in thin films of Y-Ba-Cu-O grown on  perovskite or cubic substrates. At substrate heater temperatures in the range of 780–820 °C c-axis oriented growth is observed on these substrates. On SrTi03, the first layer appears to be either a BaO or a CuO2plane while on LaA103the first layer appears to be a CuO chain layer. The mismatch on the a-b plane is accommodated by the formation of interface dislocations. Defects on the substrate surface propagate as defects in the film. These defects are primarily translational boundaries and in some cases second phases. At lower substrate heater temperatures, i.e., 650–700 °C, a, b-axis growth dominates. Defects and steps on the substrate surface are more detrimental in the growth of a, b-axis oriented films, since they tend to favor the nucleation of c-axis oriented domains. This is ascribed to the ledge mechanism of c-axis film growth, for which the surface steps are good nucleation sites. © 1991, Materials Research Society. All rights reserved.
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