Lead Titanate Thin Films Research Articles

Domain Walls Creep in Thin Ferroelectric Films

The switching processes in lead titanate thin films in subcritical rectangular pulsed fields have been investigated. Based on the obtained results, the dynamic exponent factor in the dependence of the domain wall velocity on the value of external field has been evaluated. It was shown that the value of the exponent factor increases as the film thickness decreases. The growth of the dynamic factor is associated with an increase in the crystallite axes orientation, when the thickness of polycrystalline films decreases.

The role of nanoporosity on the local piezo and ferroelectric properties of lead titanate thin films

Nanoporous PbTiO3 films present enhanced tetragonality at lower temperatures than respective dense films. Moreover, the porosity present in the nanoporous films allows an increase of the local piezoelectric response and a decrease of the local coercive field. As a result, these nanoporous films might be used to improve the switching behaviour of ferroelectric thin films.

The potential role of amorphous lead titanate thin films as nanodielectric layer for capacitor applications

A Study of thin films preparation faces many challenges due to the environmentally sensitivity that could initiate effect towards device performance. Requirement to fabricate the passive device like capacitor at such nanoscaled thickness is quite challenges that would initiate the effect on the device performance. Nowadays, capacitor not just only existed by conventional dielectric material, it can become a complex device when ferroelectric materials get involved. This material promotes useful knowledge of their polarization behavior which contains switching element that premier contribution for memory storage applications. The present study demonstrates the potential of amorphous PbTiO3 thin films as nanodielectric layer for high performance capacitor at low voltage applications. This unique characteristic of amorphous structure performs such incredible high dielectric constant value about ~100 and tangent loss of 4-5%, measured at 1 kHz. The PbTiO3 films also involve other electrical measurement like P-E hysteresis loop.

Effect of Addition Pb Content on Lead Titanate Thin Films for MIM Capacitor

Lead titanate (PbTiO3) has been precisely studied on the films preparation due to its unique perovskite structure having ferroelectric behaviour with high permittivity factor for complex storage applications such as capacitor, transistor, and ferroelectric random access memory. In the need to have high quality (PbTiO3) thin films, the lead (Pb) volatilization during crystallization process by means of applying heat treatment as part of crystal growth purpose must be realized. Therefore addition of Pb excess is the highest consideration in lead based composite to ensure perfect crystal growth ever form as well as yield to great particles polarization. There are some issues like fatigue, imprinting, and leakage current that need to be considered to assess the thin films performance. However, the present study focuses only on the crucial issue of leakage current behaviour of the nanoscaled thickness that might be in relation to the microstructural properties of the thin films. Thus, the influence of having extra Pb content might ascertain the benefits of PbTiO3 thin films towards high performance metal-insulator-metal capacitor.

Effect of Molar Concentration on Electrically Resistive Lead Titanate Thin Films by Simple Sol-Gel Method

Lead titanate thin films were successfully prepared using a simple sol-gel method. In the present study extra Pb excess was not taken into consideration in such a way that the ratio of Pb:Ti is 1:1. Different molar concentration (0.1, 0.2, 0.3, 0.4, and 0.5) involved in this study and it was found that the solutions increased in acidic level by the increment of molar concentration that being measured by pH and conductivity meter (JENWAY-3540). It also indicated that the solutions were electrically resistive at low concentration which might due to the existence of lead and oxygen ionic bonding. The solutions were then deposited onto cleaned glass substrate by spin coating technique indeed to have better thin film homogeneity at room temperature. The prepared thin films were characterized on electrical property considering the resistivity measured by solar simulator (BUKOH KEIKI EP-2000). After that structural and physical property of thin films were observed by atomic force microscopy (Park System, XE-100).

Thickness Dependency on Dielectric Property of Lead Titanate Thin Film

Previous studies have shown that lead titanate (PbTiO3) with its full potential brings out the ferroelectric property provided by its perovskite structure. It was predicted that from origination to become a modified lead titanate is most preferable, i.e. lead zirconium titanate (PZT). In the present study, PbTiO3 thin films were made through a simple sol-gel method by using spin coating technique. The deposition of thin films was at constant rate, 100rpm/s and took about 25s to complete. The fabricated thin films were then annealed at different temperature. After that, the films thickness measurement was taken by surface profiler (KLA Tencor) and characterization on dielectric property comprised at different anneal temperature. This feature indicates the power loss that will be taken into account under ac condition. The measurement of thin films was executed at 1Hz to 1MHz by using impedance spectroscopy analyzer (Solartron S1 1260A-1296) and electrical part was measured by solar simulator (BUKOH KEIKI EP-2000).

High pyroelectric coefficient modified lead titanate thin films deposition using gold electrode

Reported is the deposition and characterisation of lead zirconium titanate (PbZr0.4Ti0.6O3) (PZT) and lead calcium titanate (Pb0.7Ca0.3Ti03) (PCT) deposited on a gold electrode with a gold top electrode to form a capacitor structure. Pulsed laser deposition was utilised to deposit the thin films. The thin films were characterised for their dielectric constant and loss tangent variation with temperature as well as the pyroelectric coefficient. The thin films were poled to improve the pyroelectric effect. The highest pyroelectric coefficient was found to be 280 µC/m2 K for PZT film and 400 µC/m2 K for the PCT film after poling.

Perovskite-Structured PbTiO3 Thin Films Grown from a Single-Source Precursor

Perovskite-structured lead titanate thin films have been grown on FTO-coated glass substrates from a single-source heterometallic molecular complex, [PbTi(μ2-O2CCF3)4(THF)3(μ3-O)]2 (1), which was isolated in quantitative yield from the reaction of tetraacetatolead(IV), tetrabutoxytitanium(IV), and trifluoroacetic acid from a tetrahydrofuran solution. Complex 1 has been characterized by physicochemical methods such as melting point, microanalysis, FTIR, (1)H and (19)F NMR, thermal analysis, and single-crystal X-ray diffraction (XRD) analysis. Thin films of lead titanate having spherical particles of various sizes have been grown from 1 by aerosol-assisted chemical vapor deposition at 550 °C. The thin films have been characterized by powder XRD, scanning electron microscopy, and energy-dispersive X-ray analysis. An optical band gap of 3.69 eV has been estimated by UV-visible spectrophotometry.

Direct Observation of Atomic Arrangement around 90° Domain Wall in Lead Titanate Thin Films.

AbstractThe growth mechanism of large-size domains in PbTiO3/SrTiO3 heteroepitaxial thin films was examined using annular bright field (ABF) – scanning transmission electron microscopy and geometric phase analysis (GPA). {101} domain walls surrounded 90° domains. The large 90° domain grows by the coalescence of the nano-size domains of less than 5 nm width. A strain map obtained from the GPA of ABF-STEM image showed that 90° domains interacted elastically and attractively with edge dislocations at PbTiO3/SrTiO3 interface through simple shear strain.

The effect of post deposition anneal temperature on the structure of BiFeO3–PbTiO3 thin films

Pulsed laser deposition was used to produce 0.7BiFeO3–0.3PbTiO3 bismuth ferrite–lead titanate thin films on polycrystalline platinised silicon substrates. The films were post deposition annealed at different temperatures ranging from 500 to 700°C in an oxygen atmosphere for 30min. The films annealed at 500–550°C possess a single perovskite phase tetragonal structure, with (001) preferred orientation appearing in films annealed at 550°C. Films annealed at 600°C possess a mixed tetragonal–rhombohedral perovskite phase structure with {100} preferential orientation. At anneal temperatures between 650 and 700°C, non-perovskite secondary phases are present with the film structure. The ability to tailor film crystallographic structure and texture using varying anneal temperatures is discussed.

Nanoporous Piezo- and Ferroelectric Thin Films

Nanoporous barium titanate and lead titanate thin films (∼100 nm calculated from ellipsometric data) are prepared starting from sol-gel solutions modified with a commercially available block-copolymer and evaporation-induced self-assembly methodology. The tuning of the thermal treatment followed by in situ ellipsometry allows the decomposition of the organic components and of the structuring agent leading to the formation of porous tetragonal crystalline perovskite structures as observed by XRD, HRTEM, SEM, and ellipsoporosimetry. Both nanoporous barium titanate and lead titanate thin films present local piezoelectric and ferroelectric behavior measured by piezoresponse force microscopy (PFM), being promising platforms for the preparation of the generation of new multifunctional systems.

Strain tunability of dielectric and ferroelectric properties in epitaxial lead titanate thin films

Many distinguished properties of epitaxial ferroelectric thin films can be tunable through the misfit strain. The strain tunability of ferroelectric and dielectric properties in epitaxial lead titanate ultrathin films is numerically investigated by using a phase field model, in which the surface effect of polarization is taken into account. The response of polarization to the applied electric field in the thickness direction is examined with different misfit strains at room temperature. It is found that a compressive misfit strain increases the coercive field and the remanent polarization while a tensile misfit strain decreases both of them. The nonlinear dielectric constants of the thin films with tensile misfit strains are much larger than those of the thin films without misfit strains, which are attributed to the existence of the a/c/a/c multiple domains in the thin films under tensile misfit strains.

Piezoelectric Materials Synthesized by the Hydrothermal Method and Their Applications.

Synthesis by the hydrothermal method has various advantages, including low reaction temperature, three-dimensional substrate availability, and automatic polarization alignment during the process. In this review, powder synthesis, the fabrication of piezoelectric thin films, and their applications are introduced. A polycrystalline lead zirconate titanate (PZT) thin film was applied to a micro ultrasonic motor, and an epitaxial lead titanate (PbTiO3) thin film was estimated as a ferroelectric data storage medium. Ferroelectric and piezoelectric properties were successfully obtained for epitaxial PbTiO3 films. As lead-free piezoelectric powders, KNbO3 and NaNbO3 powders were synthesized by the hydrothermal method and sintered together to form (K,Na)NbO3 ceramics, from which reasonable piezoelectric performance was achieved.

Effects of annealing technique and TiO 2 seed layer on the phase composition of 0.7Pb(Mg 1/3Nb 2/3)O 3–0.3PbTiO 3 film

The lead magnesium niobate–lead titanate (PMN–PT) thin films with and without the TiO 2 seed layer were prepared by a pulsed laser deposition (PLD) deposited on Pt/Ti/SiO 2/Si substrates. The films were treated by two-step annealing and normal annealing with rapid thermal annealing (RTA). The effects of two-step annealing and the TiO 2 seed layer on the phase composition of PMN–PT films were studied. The results show that the PMN–PT film with TiO 2 seed layer can gain a pure perovskite phase with a high (1 0 0) preferential orientation after the two-step annealing technique.

Polarization direction and stability in ferroelectric lead titanate thin films

In this article, we examine the initial polarization of PbTiO3 thin films grown epitaxially on SrRuO3 electrodes. It is found that the as-grown predominant polarization is directed toward the SrRuO3 bottom electrode in films thinner than 20 nm and directed toward the top surface in thicker films. The data is interpreted in terms of a Landau–Ginzburg–Devonshire model for a semiconducting ferroelectric with asymmetric boundary conditions. Based on the measured hysteresis loops and the stability of the two polarization directions with time, it is concluded that charged defects serve to impose a preferential downward polarization in very thin films.

Frequency dependence of the coercive field and the internal bias field in ferroelectric thin films

The dependences of the coercive field and the internal bias field on the switching field frequency for lead zirconate titanate and lead titanate thin films are experimentally studied over a wide temperature range. It is shown that, as the frequency increases, the coercive field and the bias field in these films increase at the rate dependent on the temperature and the substrate used.

Switching Frequency Dependence in Thin Films of Lead Titanate and Lead Zirconate Titanate

The dependencies of coercive field and internal bias field on the frequency of the applied external field were experimentally studied in the films of lead titanate and lead zirconate titanate in a wide temperature range. It was demonstrated that with the frequency increase in the above films a build up of coercive field and internal bias field is observed, the rate of which depends on the temperature. The nature of the above phenomenon was analyzed and its relation to activation processes accompanying switching in ferroelectrics was shown.

Origin of Compressive Residual Stress in Alkoxide Derived PbTiO3 Thin Film on Si Wafer

In this paper, we describe the estimation of residual stress in the alkoxide-derived lead titanate (PTO) thin film on Si substrate by X-ray diffraction (XRD) and Raman analyses. The residual stress that was estimated by XRD and Raman analyses was compressive, and the values obtained by both methods were nearly the same. The residual stress in the PTO thin film increased with decreasing film thickness. We also attempted to calculate the theoretical stress in PTO thin films with random orientation. From the theoretical calculations, the thermal stress that comes from the difference in the thermal expansion coefficient between the Si substrate and the PTO film is calculated to be tensile. On the other hand, the phase transition stress is calculated to be compressive. In addition, this compressive phase transition stress canceled out the tensile thermal stress.

Effect of titanium dioxide (TiO 2) seed layer on the phase composition of 0.7Pb (Mg 1/3Nb 2/3)O 3–0.3PbTiO 3 film prepared by pulsed laser deposition

Lead–magnesium niobate–lead titanate (PMN–PT) thin films with and without the TiO 2 seed layer were deposited on Pt/Ti/SiO 2/Si substrates through pulsed laser deposition. The study aimed to characterize the effect of the TiO 2 seed layer on the phase composition and properties of PMN–PT film. Without the TiO 2 seed layer, the pure perovskite phase could be obtained in the thinner PMN–PT film while with the TiO 2 seed layer, the pure perovskite phase was formed in the thicker PMN–PT film. The ferroelectric properties of PMN–PT films with the TiO 2 seed layer were exhibited. As a result, the maximum amount of remnant polarization reached the amount of 32 μC/cm 2 for the PMN–PT thin film with the TiO 2 seed layer.

THIN FILMS OF UNDOPED LEAD TITANATE: MORPHOLOGY AND ELECTRICAL PROPERTIES

ABSTRACT The synthesis of lead titanate thin films by two different chemical solution deposition routes and via nanoparticle dispersions is described. The differences in decomposition kinetics of the solutions were determined and correlated to the morphology evolution and ferroelectric characteristics of the deposited films. High remanent polarisation values of up to 55 μC cm−2 were obtained by the sol-gel method as well as the nanoparticle dispersion technique. Measurements of the dielectric properties of the films revealed low leakage current densities in the range of 10−6 A cm−2 and a maximum dielectric constant of ∼360.