Structural study of epitaxial NdBa₂Cu₃O_7- films by laser chemical vapor deposition

Epitaxial NdBa₂Cu₃O_7- films were prepared on (100) LaAlO₃ single crystal substrates by laser chemical vapor deposition (laser CVD). The effect of deposition temperature on preferred orientation, crystallinity, microstructure, deposition rate of films was investigated. The preferred orientation of the NdBCO films changed from a, c-axis to c-axis, then back to a, c-axis, as the deposition temperature was increased from 993 to 1093 K. The highly c-axis-oriented epitaxial NdBa₂Cu₃O_7- film with critical transition temperature of 87 K was obtained at T _dep = 1033 K, with the in-plane epitaxial orientation relationship of NdBCO [100]∥LAO [010] and NdBCO [010]∥LAO [001]. The growth orientation varied from a-axis to c-axis as the film thickness increased in the case of the a, c-co-oriented NdBCO film. The contribution of thickness-dependent strain relaxation to preferred orientation of the NdBCO films was also discussed.