Ferroelectricity of one-axis-preferred-oriented polycrystalline Pb(Zr,Ti)O3 films prepared by pulsed-metalorganic chemical vapor deposition

(100)- and/or (001)-preferred-oriented and (111)-preferred-oriented polycrystalline Pb(Zr,Ti)O-3 (PZT) films with Zr/(Zr+Ti) ratios of 0.35 and 0.62, corresponding to tetragonal and rhombohedral PZT, respectively, were compared with that of epitaxially grown ones with the same composition and similar orientation from the viewpoint of crystal structure and ferroelectricity. (100)- and/or (001)-preferred-oriented and (111)-preferred-oriented polycrystalline PZT films were deposited on (111) Pt/Ti/SiO2/Si substrates at 580 and 415 degreesC, respectively, by pulsed-metalorganic chemical vapor deposition (pulsed MOCVD). On the other hand, epitaxially grown PZT films with the same composition and similar orientation were deposited on SrRuO(3)parallel toSrTiO(3) substrates at 580 degreesC also by pulsed MOCVD. The difference in ferroelectricity between the polycrystalline and epitaxial films was found to be mainly due to the film composition rather than to the film orientation. Polycrystalline tetragonal PZT films deposited by pulsed MOCVD showed almost the same remanent and saturation polarizations (Pr and Ps) as the epitaxially grown ones corrected for film orientation even though the films were deposited at a low temperature of 415 degreesC. Moreover, the coercive field (Ec) values were almost the same. On the other hand, the polycrystalline rhombohedral films showed almost the same Ps value as the epitaxially grown ones, but their Pr value was smaller than that of the epitaxial ones. Moreover, the Ec value of the polycrystalline films was smaller than that of epitaxially grown ones. The difference in ferroelectricity between tetragonal and rhombohedral PZT is strongly related to the film composition's dependence on the domain wall stability when the electric field is released. (C) 2002 American Institute of Physics.