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Epitaxial Pb(Zr,Ti)O3 (PZT) thick films of 2.0–3.0 μm thickness were grown at 600 °C on (100)cSrRuO3∥(100)SrTiO3 and (100)cSrRuO3∥(100)LaNiO3∥(100)CaF2 substrates by pulsed-metal organic chemical vapor deposition. All films showed (100) and/or (001) orientations with tetragonal symmetry. It was found that there is an almost linear relationship between the estimated thermal strain from the deposition temperature to the Curie temperature and the volume fraction of (001) orientation in the mixture of (100) and (001) orientations for the films on both substrates. Consequently, the perfectly (001)-oriented, i.e., polar-axis-oriented, PZT thick films were obtained on CaF2 with the Zr/(Zr+Ti) ratio from 0.20 to 0.40. Moreover, the lattice parameter of a- and c-axes and their ratio (c/a) of those polar-axis-oriented films were almost the same as the reported data for the powder, suggesting that the large strain is not remaining in those films. The relative dielectric constant ([variant_greek_epsilon]r) of the polar-axis-oriented Pb(Zr0.35Ti0.65)O3 thick film on CaF2 was 180 at 1 kHz, which is lower than that of (100)/(001)-oriented thick films on SrTiO3 but almost agrees with the theoretically calculated value for the c-axis of PZT single crystals. Well saturated polarization-electric-field hysteresis loops with a good square shape were observed for the polar-axis-oriented thick films, and the saturation polarization and the coercive field values were 74 μC/cm2 and 64 kV/cm, respectively. These data clearly show that the electrical properties of the polar-axis-oriented epitaxial thick films are similar to the theoretical predictions for PZT single crystals. [ABSTRACT FROM AUTHOR]

Epitaxial (100)/(001)-oriented PbTiO3 films with thickness of 2.8 μm were grown on Nb-doped (100) SrTiO3 substrates by pulsed metal organic chemical vapor deposition. Complex domain structures consisting of c-domains (c1) and three types of a-domains (a1, a2, and a3) were observed by piezoresponse force microscopy in conjunction with high-resolution x-ray diffraction analysis. The obtained results suggest that (a2/a3) and (a1/c1) domain configurations represent mostly strain-relaxed structures. This conclusion is in good agreement with theoretical predictions made for thick films [Phys. State., Solidi 37, 329 (1976)]. [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]

(100)/(001)-oriented epitaxial PbTiO3 films thicker than 1 μm were grown on various types of substrates by chemical vapor deposition. The domain structures of these films with different volume fractions of (001) were investigated. Domain structures, consisting of (100)/(001)-oriented domains, were observed regardless of the type of substrate. However, the tilting angles of the a- and c-domains from the surface normal linearly changed with the volume fraction of the (001) orientation. These results suggest that the volume fraction of the (001) orientation is crucial in identifying the domain structure of PbTiO3 thick films. [ABSTRACT FROM AUTHOR]

The authors grew (001)- and (001)/(100)-oriented epitaxial PbTiO3 films with various thicknesses on (100)SrTiO3 substrates. They used x-ray diffraction to measure the angles between surface normal [001] of (001)-oriented domains and [100] of (100)-oriented domains. The angles were found to be approximately 3.6° when the film thickness exceeded 1100 nm. This value is consistent with the value obtained by a geometric calculation for strain-free PbTiO3. This result suggests that thick epitaxial PbTiO3 films grown on (100)SrTiO3 substrates have a fully strain-relaxed structure. [ABSTRACT FROM AUTHOR]