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The occupation sites of Dy- or Y-substituted PZT films were identified using Raman spectroscopy, and the correlation between the occupation site and ferroelectric property was investigated. When Dy or Y was less than 2%, the ferroelectric properties improved because substitution occurred at the B-sites of the PZT films. However, the ferroelectric properties decreased when the substituted ions exceeded 4% because substitution occurred at both B- and A-sites. Consequently, it is important to accurately introduce substituted ions into the B-sites in a PZT film to improve the ferroelectric properties. [ABSTRACT FROM AUTHOR]

Tetragonal Pb(Zr, Ti)O3 films were epitaxially grown on SrRuO3-coated SrTiO3 substrates by metal organic chemical vapor deposition. Perfect polar-axis-oriented 50 nm thick tetragonal films were successfully grown on (100)SrRuO3//(100)SrTiO3 substrates. The single phase of the tetragonal symmetry region was expanded to a Zr/(Zr + Ti) ratio of around 0.6 for these films but was reduced to around 0.4 when (100)/(001)-mixture oriented 250 nm thick films were obtained. The dependence of spontaneous polarization (Ps) on the lattice parameter of c-axis to a-axis (c/a ratio) was demonstrated using perfectly polar-axis-oriented films with various Zr/(Zr + Ti) ratios. The 250 nm thick (100)/(001), (110)/(101), and (111)-oriented tetragonal films were grown on (100), (110), and (111)-oriented substrates. The domain structure was analyzed in detail, and it was found that the observed saturation polarization (Psat) value can be explained by the Ps value and the 90° domain contribution. These data clearly demonstrate the importance of epitaxial film research for actual ferroelectric random access memories applications. [ABSTRACT FROM AUTHOR]