Large remanent polarization of 100% polar-axis-oriented epitaxial tetragonal Pb(Zr0.35Ti0.65)O3 thin films

Abstract

100% polar-axis (c-axis)-oriented epitaxial Pb(Zr0.35Ti0.65)O3 (PZT) thin films were grown and their large remanent polarization (Pr) was directly measured. Perfectly c-axis-oriented epitaxial PZT thin films were obtained on (100)cSrRuO3//(100)SrTiO3 substrates when the deposition temperature increased to 540 °C together with a decrease in the film thickness down to 50 nm. Polarization–electric-field hysteresis loops were well saturated and had a square shape. The Pr of a 50 nm thick film saturated at 0.9 V, and its value was over 90 μC/cm2; almost independent of the measurement frequency within the range from 20 Hz to 1 kHz. This value was in good agreement with the estimated one from the a- and c-axes mixture-oriented epitaxial PZT film having the same composition taking into account the fact that only the c-axis-oriented domain contributed to the polarization. On the other hand, the coercive field value of a perfectly c-axis-oriented film was 140 kV/cm and almost the same as that of the mixture-oriented one having the same film thickness. These results show that PZT has a large Pr applicable for high-density ferroelectric random access memory.

Shifting of the morphotropic phase boundary and superior piezoelectric response in Nb-doped Pb(Zr, Ti)O3 epitaxial thin films

“…4b, suggesting that the E c value is strongly influenced by the tetragonality (c/a) in the epitaxial films. These dependencies of the ferroelectric property on Zr/Ti ratios for epitaxial PNZT thin films are quite different from the dependencies in bulk polycrystalline PZT ceramics where P r exhibits its maximum value at the MPB of the bulk PZT, that may be due to the P r value of PZT ceramics depends primarily on their polarizability while the P r value of epitaxial PNZT films depends primarily on the intrinsic contributions from c-domains [33].…”

Structural transition on Pb1−xSrxTiO3 produced by chemical method

“…The dependence of the additive concentration on the ferroelectric-paraelectric transition has been demonstrated in several solutions as, for example, Pb x Ca 1−x TiO 3 (PCT), Pb x Sr 1−x TiO 3 (PST), and PbZr 1−x Ti x O 3 (PZT). The last one has been extensively studied due to its useful piezoelectric properties [4,[12][13][14][15]. Chu and Chen [16] also observed Sr-doping effect on Sm-modified PT and verified that it can reduce the lattice anisotropy (c/a), and keep good dielectric and piezoelectric anisotropy properties.…”

Domain distributions in tetragonal Pb(Zr,Ti)O3 thin films probed by polarized Raman spectroscopy

“…The x-ray reciprocal space mapping ͑PANalytical X'Pert MRD͒ was measured for estimating the volume fraction of the polar-oriented c domain in the films having the mixture orientation of ͑00ᐉ͒ ͑c domain͒ and ͑h00͒ ͑a domain͒, followed by the same procedure as in Ref. 9. Here, we collected the reciprocal mappings of the in-plane and out-ofplane lattice parameters, and the relative volume fraction of the c domain, V͑00ᐉ͒ / ͓V͑h00͒ + V͑00ᐉ͔͒, is estimated using a͒ Author to whom the correspondence should be addressed; electronic mail: osada.minoru@nims.go.jp the integrated intensities of the PZT204/402 spots.…”

“…[9][10][11] The film thickness was changed from 150 nm to 4.7 m by controlling the deposition time. The compositions of PZT were x = 0.35± 0.02, which correspond to the Ti-rich tetragonal region of the morphotropic phase boundary.…”

“…Details of preparation and characterization are described elsewhere. [9][10][11][12] Raman spectra were measured with the 514.5 nm line from an Ar + laser ͑ϳ1 mW͒ by focusing on a 1 -2-m-diam spot on the sample surface. The backward scattering light was collected and dispersed by a subtractive triple spectrometer ͑Jobin-Yvon T64000͒ equipped with a liquid-nitrogencooled charge-couple-device detector.…”