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PZT thin films are one of the most effective materials attractive for MEMs applications. In this research, high-quality PZT thin films were deposited on (111)Pt/Ti/SiO 2 /(100)Si substrates by RF magnetron sputtering from a Pb(Zr 0.52 Ti 0.48)O 3 ceramic target. The sputtered PZT films with deposition times of 90 min–180 min were annealed at different temperatures; 550°C-700 °C. The results indicated that the film's crystallinity, density, and morphology were affected by the sputtering time and the annealing conditions due to grain growth. Post-annealing improved the microstructure and properties of PZT thin films. The increase in annealing temperatures virtually caused the decrease of PZT thin-film thickness. Densification and PZT grain size were found to increase with increasing annealing temperatures. The XRD and SEM results demonstrated that the PZT thin films were well-crystallized and contained a uniform grain distribution. With sputtered time of 90 min, 120 min, 150 min, and 180 min, the thickness of PZT thin films were 168 nm, 228 nm, 266 nm, and 275 nm, respectively. WDS results showed that the atomic percentages of zirconium content decreased by increasing annealing temperature. At the 180 min-sputtered time, the remaining lead content after annealing temperatures of 550°C–700 °C showed an estimated 1.0 at%. Increased annealing temperatures affected significantly lead loss due to volatilization. The surface roughness was confirmed by AFM analysis of the proposed systems. The roughness values of films increased from 1.28 nm to 4.25 nm with increasing annealing temperature. The dielectric functions (ε 1) and (ε 2) of sputtered PZT thin films at different annealed temperature and different thicknessess were analyzed by Spectroscopic Ellipsometry (SE). The (ε 1) and (ε 2) of as-deposited PZT thin film showed different dispersion shapes, and (ε 2) amplitude was shifted to the lower photon energy in comparison with annealed PZT thin films, which can correspond to differences in the crystal structure. [ABSTRACT FROM AUTHOR]

PbTi 1-x Zr x O 3 (PZT) thin films prepared by sol-gel method have paid much attention due to the excellent performances in piezoelectric, dielectric, ferroelectric and electro-optical. However, the high crystallization temperature of the PZT thin films restricts the compatibility with modern COMS technology. In this work, PbZr 0.52 Ti 0.48 O 3 (PZT) ferroelectric thin films were successfully prepared by sol-gel method at an ultra-low temperature (∼450 °C) in an oxygen plasma-assisted environment. A large spontaneous polarization ∼30 μC/cm2 and a large dielectric breakdown ∼2,900 kV/cm were obtained in the sample annealed at 450 °C for 25 h. We believe that the oxygen plasma-assisted ultra-low temperature (OPAULT) annealing process is a promising way for the sol-gel technology applied in the modern COMS devices. [ABSTRACT FROM AUTHOR]

In this research, the effects of annealing temperatures on the crystallization and morphology of Pb(Zr0.52Ti0.48)O3 (PZT) thin films on (111) Pt/Ti/SiO2/(100)Si and (111) Au/Cr/(100)Si substrates prepared by RF magnetron sputtering were investigated. Two types of thin films: PZT/Pt/Ti/SiO2/Si and PZT/Au/Cr/Si were obtained from a Pb(Zr0.52Ti0.48)O3 ceramic target and were annealed at different temperatures of 600 °C, 650 °C, and 700 °C for 1 h, in air, with heating rate of 5 °C/min. The XRD studies showed that the crystal structures of the PZT thin films could be affected by varying annealing temperatures. The annealed PZT thin films exhibited perovskite structures that crystallographic orientations increased remarkably with annealing temperatures. Phases of PZT thin films on two types of substrates oriented differently. The FE-SEM images along with energy dispersive spectroscopy (EDS) studies confirmed the homogeneous and compact films. The increase of annealing temperatures virtually caused the decrease of PZT thin-film thickness, increase of densification of the films, and increase of PZT grain size. Moreover, the phase composition state of the PZT thin films changed quantitatively with increase in annealing temperatures. The dielectric, ferroelectric and piezoelectric properties of PZT thin films will be further investigated. [ABSTRACT FROM AUTHOR]

Charge transport mechanisms governing DC resistance degradation in ferroelectric films are influenced by defects, particularly oxygen vacancies. This paper demonstrates that oxygen vacancies migrate in lead zirconate titanate (PZT) films under a DC bias field and contribute to resistance degradation. Model PZT thin films were developed in which the concentration and distribution of oxygen vacancies were controlled via (a) changing the dopant type and concentration from 1%–4% Mn (acceptor) to 1%–4% Nb (donor) or (b) annealing undoped PZT films at varying partial pressures of PbO. The presence of associated (immobile) and dissociated (mobile) oxygen vacancies was distinguished by thermally stimulated depolarization current (TSDC) measurements. The impact of mobile oxygen vacancies on local defect chemistry and associated charge transport mechanisms was explored by electron energy loss spectroscopy (EELS). For Mn‐doped PZT films, following resistance degradation, TSDC studies revealed only one depolarization peak with an activation energy of 0.6–0.8 eV; this peak was associated with ionic space charge presumably due to migration of oxygen vacancies. The magnitude of the depolarization current peak increased with increasing degradation times. A similar depolarization current peak attributed to the existence of mobile oxygen vacancies was also observed for undoped and Nb‐doped PZT films; the magnitude of this peak decreased as the Nb or PbO contents in PZT films increased. An additional TSDC peak associated with polaron hopping between Ti3+ and Ti4+ was found in both Nb‐doped PZT films and undoped PZT films annealed under low PbO partial pressure. Degraded Nb‐doped samples exhibited a chemical shift in the TiL2,3 peak to lower energy losses and the appearance of shoulders on the t2g and eg peaks, implying a reduction of Ti cations in regions near the cathode. [ABSTRACT FROM AUTHOR]

This work reports on direct crystallization of PbZr 0.53 Ti 0.47 O 3 (PZT) thin films on glass and polymeric substrates, using pulsed thermal processing (PTP). Specifically, xenon flash lamps deliver pulses of high intensity, short duration, broadband light to the surface of a chemical solution deposited thin film, resulting in the crystallization of the film. Structural analysis by X-ray diffraction (XRD) and transmission electron microscopy show the existence of perovskite structure in nano-sized grains (≤5 nm). Local functional analysis by band excitation piezoelectric spectroscopy and electrostatic force microscopy confirm the presence of a ferroelectric phase and retention of voltage-written polarization for multiple days. Based on structural and functional analyses, strategies are discussed for optimization of pulse voltage and duration for the realization of crystalline ferroelectric thin films. For ∼200 nm-thick PZT films on glass substrates, 500 μs-long pulses were required for crystallization, starting with 100 pulses at 350 V, 10 or 25 pulses at 400 V and in general lower number of pulses at higher voltages (resulting in higher radiant energy). Overall power densities of >6.4 kW/cm2 were needed for appearance of peaks corresponding to the perovskite phase in the XRD. Films on glass processed at 350–400 V had a higher degree of 111-oriented perovskite grains. Higher applied radiant energy (through increased pulse voltage or count) resulted in more random and/or partially 001-oriented films. For ∼1 μm-thick PZT films on polymeric substrates, 10 to 25 250 μs-long pulses at voltages ranging between 200 to 250 V, corresponding to power densities of ∼2.8 kW/cm2, were optimal for maximized perovskite phase crystallization, while avoiding substrate damage. [ABSTRACT FROM AUTHOR]

The intrinsic contribution of dielectric permittivity was obtained in thin films of PZT pyrolyzed at different temperatures. Pyrochlore phases were observed in films pyrolyzed at temperatures above 350 °C, while only the perovskite phase grows in films pyrolyzed at temperatures lower than 300 °C. Dielectric and ferroelectric properties were characterized, and their behaviors were related to pyrolysis temperature. The dielectric permittivity dependence on the bias electric field was investigated at room temperature for different PZT thin films, and these curves were used to reconstruct the hysteresis loops. In this work, a model was used to reconstruct the hysteretic behavior of the films. The experimental results are in excellent agreement with the applied model. [ABSTRACT FROM AUTHOR]

Electric properties for ferroelectric lead zirconate titanate (PZT50/50, 45/55, 40/60, 30/70) thin films on base metal plates with different thermal expansion coefficient (TEC) were calculated by a phenomenological model. Results show that when the TEC of substrates increases, dielectric constant, tunability and piezoelectric coefficient d 33 of all PZT thin films with tetragonal phase are decreased due to the larger compressive thermal strain. PZT50/50 thin films deposited on smaller TEC substrates can achieve higher dielectric constant, tunability and d 33. The computed dielectric constant of PZT50/50 thin films is in accordance with the measured results from sol-gel experimental process, and the trend of dielectric constant of PZT films adjacent to morphotropic phase boundary (MPB) derived from some references also agrees with that from calculation. These results suggest that higher tunability and d 33 of PZT films can be obtained by choosing smaller TEC substrates. [ABSTRACT FROM AUTHOR]

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Abstract One of the challenges in fabricating pyroelectric infrared (PIR) detector arrays using microelectromechanical system (MEMS) technique lies in finding an optimal growth method of sensing thin films. In this study, lead zirconate titanate (PbZr 0.3 Ti 0.7 O 3 , PZT) thin films were successfully prepared on Pt/TiO 2 /Si 3 N 4 /SiO 2 /Si substrates by RF magnetron sputtering. The structure, morphology and electrical properties of the films annealed at different temperatures were investigated. PZT thin films deposited at a working pressure of 3.0 Pa with an Ar/O 2 gas flow ratio of 80/20 and annealed at 700 °C exhibited smooth surface and excellent dielectric, ferroelectric and pyroelectric properties. The dielectric constant and the loss tangent of the films are 500 and 0.018 at 1 kHz, respectively. The remnant polarization (P r) and the coercive field (E c) of the films are 33 μC cm−2 and 42 kV cm−1, respectively. The pyroelectric coefficient of the films is 0.033 μC cm−2 K−1. The value of the figure of merit of detectivity (F D) of PZT thin films reaches up to 1.29 × 10−5 Pa−1/2, which indicates that the films have met the requirements for sensitive layers utilized in pyroelectric infrared detector arrays. [ABSTRACT FROM AUTHOR]

Abstract: For piezoelectric energy harvesters, a large volume of piezoelectric material with a high figure of merit is essential to obtain a higher power density. The work describes the growth of highly (001) oriented sputtered lead zirconate titanate (PZT) films (f ≈ 0.99) exceeding 4 µm in thickness on both sides of an Ni foil to produce a bimorph structure. These films are incorporated in novel wrist‐worn energy harvesters (<16 cm2) in which piezoelectric beams are plucked magnetically using an eccentric rotor with embedded magnets to implement frequency up‐conversion. The resulting devices successfully convert low‐frequency vibration sources (i.e., from walking, rotating the wrist, and jogging) to higher frequency vibrations of the PZT beams (100–200 Hz). Measured at resonance, six beams producing an output of 1.2 mW is achieved at 0.15 G acceleration. For magnetic plucking of a wrist‐worn nonresonant device, 40–50 µW is produced during mild activity. [ABSTRACT FROM AUTHOR]

Abstract: A composite structure with an highly flexible polymer substrate and a thin film of lead zirconate titanate, Pb(Zr,Ti)O3 (PZT), is realized using an all‐chemical process. The fabrication of the structure comprises three steps: first, PZT is deposited on an aluminum thin foil, then the PZT thin film is bonded to a polymer, and, finally, aluminum foil is removed by selective chemical etching. Structural characterization techniques are used to ensure the quality of the PZT/polymer composite structure. Electrical measurements are also performed to confirm the ferroelectric characteristics of the composite. Finally, energy harvesting measurements are realized with interdigitated electrodes structure. A maximal energy density of 20 μJ cm−2 is obtained with manual mechanical excitation and an output voltage up to 35 V under free oscillations conditions in bending mode. This demonstrates that the recently developed PZT/polymer thin films are very promising for low‐frequency vibrating energy‐harvesting applications. [ABSTRACT FROM AUTHOR]

It is shown that the character and orientation of a self-polarization depends on the superstoichiometric amount of lead in thin Pb(Zr1-xTix)O3 films (x = 0.46) formed on a Pt/TiO2/SiO2/Si substrate by a two-stage RF-magnetron sputtering (ex-situ) method. The lead content was changed by varying the pressure of the working Ar+O2 mixture in the range of 2-8 Pa. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT) thin films deposited on Pt electrode and Pb1+x(Zr0.52,Ti0.48)O3(x = 0.10, 0.15, 0.25, 0.30) buffer layer have been prepared by sol-gel methods to investigate the effects of lead content in the buffer layer on crystalline orientation, electric and fatigue properties of PZT films. XRD and SEM showed that all films exhibited dense perovskite structure with (100) preferential orientation. The maximum dielectric constant (1571 at 100 Hz) was obtained in the PZT film with buffer layer containing 25% excess lead, which increased by 42.5% compared with the film without buffer layer. Fatigue resistance was improved by introducing buffer layer. [ABSTRACT FROM AUTHOR]

PbZrTiO thin films on stainless steel substrates were fabricated by an ethylene glycol modified sol-gel method. Perovskite structure of PbZrTiO thin films was examined by the X-ray diffraction analysis. With the increase of ethylene glycol, PbZrTiO thin films with enhanced dielectric and ferroelectric properties were got. Crack-free PbZrTiO thin films with thickness of 1.6 μm were prepared for ethylene glycol content of 50%, and the dielectric permittivity and dielectric loss were 224 and 5.4% respectively at the frequency of 1 kHz showing better dielectric properties compared with PbZrTiO thin films without ethylene glycol modified. The remnant polarization ( P ) of 50% content ethylene glycol modified PbZrTiO thin films was nearly twice reaching 12.3 μC/cm, and lower leakage current density was obtained with 4.6 × 10 A· cm under the field of 50 kV· cm. Such enhanced performance indicated that the PbZrTiO thin films prepared on stainless steel substrates by the ethylene glycol modified sol-gel process exhibited their potentiality in applications. Graphical abstract: [ABSTRACT FROM AUTHOR]

Pb(Zr0.52Ti0.48)O3 (PZT) sols were prepared by a modified sol-gel route using both solvents - acetic acid and stabilizer solution (n-propanol : 1,2-propanediol in the rate 10 : 1). The sols were deposited by spin-coating onto platinized Al2O3 or SiO2/Si substrates. Results of SEM and XRD analyses confirmed, that the transformation of the amorphous PZT film to perovskite structure happened after sintering at 650°C. The mechanism of microstructure formation has described for morphologicaly different perovskite particle types in 1, 2 and 3-layered PZT thin films with thickness of 200-500 nm on used substrates. Three different PZT film microstructure types in dependence on the applied sol concentration were found. It was found, that the PZT/Pt/Al2O3 film microstructure at 1.0 M sol concentration was composed of two forms of perovskite particles, big rosette and irregular cuboidal particles. Small spherical particles and rosette structure were found in PZT/Pt/Si/SiO2 films.

A thermal energy harvester based on a double transduction mechanism and which converts thermal energy into electrical energy by means of piezoelectric membranes and bimetals, has previously been developed and widely presented in the literature In such a device, the thermo-mechanical conversion is ensured by a bimetal whereas the electro-mechanical conversion is generated by a piezoelectric ceramic. However, it has been shown that only 19% of the mechanical energy delivered by the bimetal during its snap is converted into electrical energy. To extract more energy from the bimetallic strip and to increase the transduction efficiency, a new way to couple piezoelectric materials with bimetals has thus been explored through direct deposition of piezoelectric layers on bimetals. This paper consequently presents an alternative way to harvest heat, based on piezoelectric bimetallic strip heat engines and presents a proof of concept of such a system. In this light, different PZT (Lead zirconate titanate) thin films were synthesized directly on aluminium foils and were attached to the bimetals using conductive epoxy. The fabrication process of each sample is presented herein as well as the experimental tests carried out on the devices. Throughout this study, different thicknesses of the piezoelectric layers and substrates were tested to determine the most powerful configuration. Finally, the study also gives some guidelines for future improvements of piezoelectric bimetals.

We investigated the behavior of the capacitance and dielectric loss tangent under bias voltage in Pt/PZT/Pt thin film structures annealed at 540–570°C. Internal field in PZT films was determined on a basis ofC-Vcharacteristics. Also, the frequency dependence of the dielectric response of these films was obtained. A correlation between dielectric properties and the microstructure of the films was revealed. Observed strong dependences of electrophysical characteristics of PZT films on the annealing temperatures are evidence in favor of this correlation. [ABSTRACT FROM PUBLISHER]

Dielectric response of thin-film capacitor structures of Pt/PZT/Pt deposited by the RF magnetron sputtering method and annealed at temperatures of 540–570 °C was investigated. It was found that dielectric properties of these structures depend on the synthesis temperature. Stability of a polarized state is considered on the basis of the analysis of hysteresis loops and capacitance–voltage ( C–V ) characteristics. The contribution of the domain mechanism in the dielectric response of the capacitor structure comprising a ferroelectric is discussed. Extreme dependences of electrophysical characteristics of PZT films on their synthesis temperature were observed. Correlation of dielectric properties with microstructure of these films is found out. [ABSTRACT FROM AUTHOR]

In this paper, Pb(Zr 0.52 Ti 0.48 )O 3 (PZT) thin films were prepared via sol-gel method. The effects of Ba(Mg 1/3 Ta 2/3 )O 3 (BMT) buffer layer on the temperature dependence and dielectric tunability properties of PZT thin films were studied. As the thickness of BMT buffer layer increases, the tan δ and tunability of PZT thin films decrease while tunability still maintains above 10%. This result shows that BMT buffer layer can improve the dielectric tunability properties of PZT thin films. Furthermore, the temperature coefficient of the dielectric constant decreases from 2333.4 to 906.9 ppm/°C with the thickness of BMT buffer layer increasing in the range from 25 to 205 °C, indicating that BMT buffer layer can improve the temperature stability of PZT thin films. Therefore, BMT buffer layer plays a critical role in improving temperature dependence and dielectric tunability properties of PbZr 0.52 Ti 0.48 O 3 thin films. [ABSTRACT FROM AUTHOR]

The effects of heat treatment on the phase transformations of lead zirconate titanate Pb(Zr0.50Ti0.50)O3(PZT) thin films were studied. The pyrolysis temperature directly affected the densification, residual stresses, and suppression of the pyrochlore phase observed in the studied films. The evolution of the crystalline phases and the residual stress were characterized by different temperatures of pyrolysis in PZT thin films, using the X-ray diffraction technique. The phase transformations in the films are discussed in terms of theoretical and experimental calculations of residual stress. [ABSTRACT FROM PUBLISHER]

In this paper, Pb(ZrTi)O (PZT) thin films were prepared on Pt/Ti/SiO/Si substrates via sol-gel method. The effects of residual stress on the electrical properties in PZT thin films were investigated. There is no significant difference in grain size and orientation for PZT thin films, indicating that the influences of grain size and orientation on electrical properties of PZT thin films can be neglected. The residual stresses in PZT thin films, which decrease with increase in the film thickness, were detected by the phonon mode shift of Raman scattering. In the thin films, the interface between PZT thin films and platinum electrodes is the main factor that affected dielectric properties. As the film thickness increases, the contribution of the interface is increasingly attenuated and the residual stress is the main factor. To relieve some of the residual stress, there are more 90° domains to form, which can improve the ferroelectric and piezoelectric properties of PZT thin films. Graphical Abstract: The value of dielectric constants decreases at 1 MHz, and tan δ increases with the decrease in film thickness. In this paper, the processing was designed to control grain size and crystal orientation. Therefore, residual stress and interface are the main factors that affect the dielectric constant. For the sample with the thickness of 162 and 324 nm, there is a ~45 % increase in measured dielectric constant and this change appears to be too much to be accounted for by the residual stress alone. The main factor that affects dielectric constant in the thinner films is the interface which can dilute the effective dielectric constant. As the film thickness increases, the contribution of the interface is increasingly attenuated and there is only 4 % change in the dielectric constant, indicating that residual stress is the main factor that affected dielectric constant. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

An accuracy of elemental composition of submicron PZT films was investigated using nondestructive method of the electron probe X-ray microanalysis based on energy dispersive analyzer. PZT films RF-magnetron sputtered on Pt/SiO2/Si substrate were annealed to create the perovskite phase in the temperature range of 530-570°C. Unusual changes of lead content at elevated annealing temperatures were observed. The variation of incident angle of probing electrons was used to evaluate qualitatively lead excess on the film depth. Mechanisms of perovskite phase formation in the films are discussed. [ABSTRACT FROM PUBLISHER]

In this paper, Pb(ZrTi)O (PZT) thin films were deposited on Pt/Ti/SiO/Si substrates via sol-gel method by using Ba(MgTa)O (BMT) thin film as buffer layer. The effects of BMT buffer layer on the fatigue behavior in PZT thin films were investigated. After 1.04 × 10 reversal cycles, the remnant polarization value of buffered PZT thin films decreases only 12.1 %, while it decreases 58.2 % in PZT thin films. The results reveal that BMT buffer layer can greatly improve the fatigue properties of PZT thin films, which are related to the oxygen vacancies accumulation. The oxygen vacancies accumulation can reduce the electric field across the PZT layer and inhibit the motion of domain. BMT buffer layer can modify the PZT/Pt interface, which can reduce mobility of oxygen vacancies from PZT thin films to PZT/Pt interface. Moreover, the energy bandgap of PZT films (E = 3.6 eV) is similar to that of BMT films (E = 3.7 eV), which can minimize the oxygen vacancies accumulation. Furthermore, BMT buffer layer can reduce the residual stress, which can reduce suppression of domain switching. [ABSTRACT FROM AUTHOR]

This paper describes the effects of pyrolysis temperature and film thickness before annealing on the orientation and microstructure of the lead zirconate titanate (PZT) thin films prepared by chemical solution deposition method (CSD). Different thickness of the pyrolytic films were obtained by repeating deposition and pyrolysis with different times. The orientation and microstructures of the PZT thin films were characterized by X-ray diffractometry (XRD) and field-emission scanning electron microscope (SEM). The results show that the thickness of the pyrolytic films was the principal factor that affects the crystalline structures in PZT thin films. [ABSTRACT FROM PUBLISHER]

We report on the first peristaltic micropump with active microvalves actuated by piezoelectric thin-films. We developed an original process to combine state of the art sol-gel Pb(Zr,Ti)O3 (PZT) thin-films with a highly performing silicon micropump. The device thus takes advantage of both technologies, especially with respect to low voltage actuation and high precision. It can produce μl/min flows for 24 V actuation voltage, opening a new range of applications for low consuming pumps and autonomous microfluidic systems, especially implanted devices for drug delivery. [ABSTRACT FROM AUTHOR]

Abstract: The conduction mechanisms through a lead zirconate titanate (PZT) thin film grown by pulsed laser deposition with a La0.67Sr0.33MnO3 (LSMO) buffer layer on epitaxial Pt (111) were assessed in the 230–330K temperature range. X-Ray diffraction and transmission electron microscopy evidenced a columnar growth of (001)- and (011)-oriented PZT grains. The leakage current through the Pt/PZT/LSMO/Pt structure was then systematically measured. From current vs. time curves, a threshold voltage was found below which stable and reproducible current values are obtained, thus avoiding resistance degradation. The conduction mechanism changes from interface controlled at low temperatures to bulk controlled around room temperature. The hopping-type conductivity evidenced above 270K is consistent with the extended defects and columnar microstructure of the PZT film. [Copyright &y& Elsevier]

Pb(Zr0.52Ti0.48)O3or PZT thin films embedded with CuO nano-particles were successfully prepared by a hybrid sol-gel process. In this process, CuO (0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1wt%) nanopowder was suspended in an organometallic solution of PZT, and then coated on platinised silicon substrates using a spin-coating technique. X-ray diffraction patterns showed a perovskite phase in all the films. The CuO particles were not detected in the film, but the small amount of second phase was present when CuO concentration was above 0.4 wt%. The addition of CuO nano-particles also affected the orientation of PZT films. The CuO nano-particles were generally found to reduce both dielectric and ferroelectric properties of PZT films. However, at 0.2 wt% CuO concentration, the film exhibited good ferroelectric properties which were comparable to those of pure PZT thin films. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pulsed laser deposited PZT thin films. [•] Seed layer effect on the structural and ferroelectric properties of the PZT films. [•] The stability of P r was improved with the introduction of the LSCO layer. [ABSTRACT FROM AUTHOR]

Morphology of the surface and local ferroelectric properties of thin lead zirconate titanate (PZT) films synthesized by the sol-gel technique are studied by scanning probe microscopy. It is shown that the surface of the films has quite low roughness of ∼2 nm and small average grain size of 20 nm. It is found that the film is polarized under impact of a positive or negative potential applied to the 'probe-sample' system. The relaxation times of signals of residual ferroelectric responses are measured, and the rate of the lateral movement of the domain wall for PZT film is calculated. [ABSTRACT FROM AUTHOR]

Abstract: 2% Nb-doped [111]-oriented lead zirconate titanate films (PNZT) of different Zr/Ti ratios ranging from 30/70 to 70/30 with a fixed thickness were deposited on the Pt(111)/Ti/SiO2/Si(100) substrates by sol–gel method. The orientation degree, film morphology and phase transition of the PNZT films were investigated as a function of Zr/Ti ratios. The experimental results verified the composition-dependent phase transition from tetragonal to rhombohedral of the PNZT films with a visible [111] preferred orientation. To obtain high performance by making use of rhombohedrel [111]-oriented thin films, Pb(Zr0.6Ti0.4)Nb0.02O3 films with various thicknesses varying from 70nm to 300nm were studied to reveal the relationship among the film thickness, stress and ferroelectric response. It was found that ferroelectric property reached a high remnant polarization (P r ) of 61.7μC/cm2 and a minimum coercive field (E c ) of 70.7kV/cm at 300nm due to the release of residual tensile stress. [Copyright &y& Elsevier]

The study of conductivity of thin film capacitor structures on the basis of PZT was carried out. The obtained asymmetry ofI-Vcharacteristics showed the distinction of potential barrier height on interfaces of the Pt/PZT/Pt heterostructures, which changed depending on synthesis conditions. Time dependences of the electric current on DC voltage were investigated. Two main mechanisms of conductivity: Ohmic and Poole-Frenkel emission were revealed. [ABSTRACT FROM AUTHOR]

In this paper scanning probe microscopy investigations of surface morphology and local ferroelectric properties of sol-gel deposited PZT thin films are presented. It is shown that the films have sufficiently low surface roughness about 2 nm and small grain size about 20 nm. Possibility of the film polarization by applying both positive and negative DC voltage between the SPM probe and the sample is demonstrated. Additionally, times of residual piezoresponse signal relaxation are measured and domain wall velocity for the PZT films is calculated. [ABSTRACT FROM AUTHOR]

High quality pulsed laser deposited lead zirconate titanate (PZT) films are obtained by pulsed laser deposition on SrRuO3(111) single crystal layers and characterized by X-ray photoelectron spectroscopy (XPS), to determine the surface composition. It is found that a minor amount of Pb forms PbO2 at the surface and also some Pb is included into the contamination layer, in form of a Pb(CO3)2 layer of about 1 nm thickness, occupying about one quarter of the PZT surface. The stoichiometry of the outermost 4-5 nm layers yielded as PbZr0.25Ti0.80O2.5, which suggest the formation of an oxygen depleted, Brownmillerite-like layer at the surface, of at least 5 nm thickness. [ABSTRACT FROM AUTHOR]

High quality pulsed laser deposited lead zirconate titanate (PZT) films are obtained by pulsed laser deposition on SrRuO3(111) single crystal layers and characterized by X-ray photoelectron spectroscopy (XPS), to determine the surface composition. It is found that a minor amount of Pb forms PbO2 at the surface and also some Pb is included into the contamination layer, in form of a Pb(CO3)2 layer of about 1 nm thickness, occupying about one quarter of the PZT surface. The stoichiometry of the outermost 4-5 nm layers yielded as PbZr0.25Ti0.80O2.5, which suggest the formation of an oxygen depleted, Brownmillerite-like layer at the surface, of at least 5 nm thickness. [ABSTRACT FROM AUTHOR]

Abstract: Spontaneous Zr/Ti gradient formation during crystallization in sol–gel-processed Pb(Zr x Ti1− x )O3 films is used to prepare superlattice-like (SL), highly (100)-oriented thin films on Pt/Ti/SiO2/Si substrates. SLs with stacking periodicity ranging from 13 up to 60nm are synthesized with compositional gradient normal to the film surface and composition centered at x ≈0.53. X-ray diffraction (XRD) shows high order satellite peaks and no secondary phases. XRD structural refinement, along with XPS depth profile chemical analysis, reveals that the crystal structure alternates between rhombohedral and in-plane polarized tetragonal phases, effectively corresponding to “artificially created” phase boundaries. SL films have ∼45% and ∼20% higher d 33,f piezoelectric coefficient and dielectric permittivity, respectively, with respect to compositional-gradient-free films of similar thickness, possibly due to enhanced reorientation of electrical dipoles and higher extrinsic contributions due to the motion of the “artificially created” phase boundaries in SL films. Dielectric nonlinear studies indicate a higher amount of extrinsic contributions to the dielectric response in SL and gradient-enhanced films than in conventional films of similar average composition. This processing method provides a simple chemical route to create thin ferroelectric films with enhanced dielectric and piezoelectric properties suitable for a range of miniaturized applications. [Copyright &y& Elsevier]

Abstract: A common design of piezoelectric microactuators adopts a membrane structure that consists of a base silicon diaphragm, a layer of bottom electrode, a layer of piezoelectric thin film, and a layer of top electrode. In particular, the piezoelectric thin film is often made of lead–zirconate–titanate (PZT) for its high piezoelectric constants. When driven electrically, the PZT thin film extends or contracts flexing the membrane and generating an out-of-plane displacement. Many manufacturing defects, however, could significantly reduce the designed actuator displacement. Examples include residual stresses, warping, non-uniform etching of the silicon diaphragm, and misalignment between the top electrode and the silicon diaphragm. The purpose of this paper is to develop a dual top-electrode design to enhance the actuator displacement. In this design, the top electrode consists of two disconnected (thus independent) electrode areas, while a continuous bottom electrode serves as the ground. The two top electrodes are located in two regions with opposite curvature when the diaphragm deflects. When the two top electrodes are driven in an out-of-phase manner, the actuator displacement is enhanced. Finite element analyses and experimental measurements both confirm the feasibility of this design. When manufacturing defects are present, experimental results indicate that the actuator displacement can be optimized by adjusting the phase difference between the dual top electrodes. [Copyright &y& Elsevier]

This study investigated the crystalline orientation and electromechanical characteristics of PZT films fabricated with various concentrations of sol-gel solution, and dopants such as Nb and Zn. Crack-free and 1-μm-thick films with a pure perovskite phase were obtained on Pt/Ti/SiO2/Si by modified sol-gel deposition method. The degree of (111) orientation was promoted by a higher concentration of a sol-gel solution. Excellent electromechanical characteristics were measured in PZN-PZT films. The highest remnant polarization and d33 piezoelectric coefficient were 25.1 μC/cm2 and 240 pC/N, respectively. The sol-gel driven PZN-PZT films could be attractive for application to piezoelectrically operated microelectronic devices. [ABSTRACT FROM AUTHOR]

A thin adhesion layer is required to glue Pt bottom electrodes of ferroelectric Pb(Zr,Ti)O3 thin films to a SiO2/Si wafer. Here we report the effect of adhesion layers, Ti and TiO2, on the crystalline structure and surface properties of Pt electrode. The results show that the hillock formation is observed for the case of Ti glue layer, while the surface of Pt layer is flat and uniform with TiO2 layer used instead. The crystallization in PZT thin films on Pt/TiO2/SiO2/Si substrate is investigated during post-deposition annealing. The perovskite phase is completely formed in the film annealed at 650°C for one hour. [ABSTRACT FROM AUTHOR]

Abstract: The preparation process, micro-structure and electrical properties of Pb(Zr x Ti1− x )O3 (PZT) thin films were investigated in this paper. The Ag/PZT(x =0.95)/YBCO/Si thin films were prepared by pulsed laser deposition (PLD). Si was the substrate; Ag and YBCO were the top electrode and the bottom electrode respectively. The bottom electrode YBCO was deposited on the Si substrate by PLD, and PZT was epitaxially deposited on YBCO also by PLD. After rapidly annealing, the AFM, XRD and the analysis of their electrical characters showed the films had good ferroelectric and pyroelectric properties. At 50°C, the pyroelectric coefficient (p) was 3.5×10−8 C/(cm2 K), the remanent polarization (Pr ) and the coercive field (Ec ) were 43.6μC/cm2 and 19.3kV/cm respectively. [Copyright &y& Elsevier]

The polycrystalline Pt film with an excellent (111) orientation and a small grain size of about 30 nm was successfully prepared on a SiO2/Si substrate by the new structured-sputtering system. By optimizing annealing process and using the highly (111)-oriented Pt film as a bottom electrode, an epitaxial-grade (111)-oriented PZT film was successfully prepared by the sol-gel method. Operation of the ferroelectric-gate thin film transistor (FGT) with indium-tin-oxide (ITO) channel, which was based on the optimum Pt and PZT films, has been verified. The FGT device exhibited good properties and performance with high 'on/off' current ratio (∼105), adequate memory window (1.2 V) and small swing factor (∼88 mV/decade). [ABSTRACT FROM AUTHOR]

Lead zirconium titanate Pb (Zr0.58Ti0.42) O3 (PZT) thin films were deposited on silicon substrates by sol-gel process. The structural, morphological, dielectric and nano mechanical properties of these films have been studied systematically. The thicknesses of the films were around 160 nm. During the deposition of each layer, the films were baked in a microwave oven which in turn resulted in a low temperature crystallization of these thin films compared to the conventional method. The crystallite sizes of the films were ranged between 25-35 nm depending up on the annealing temperature. The dielectric constant of the films decreased with increase in frequency whereas the loss has increased and ranged between (480-100) and (0.03-0.30), respectively. The DFM (Dynamic force microscopy) images of the films shows the spherical grains with uniform microstructure and an average grain size of 80-110 nm. The hardness of the films ranged between 2-5 GPA. The film annealed at 600°C was having a dielectric constant of 400 with hardness of 4.8 GPa which is suitable combination of properties for micromechanical systems. [ABSTRACT FROM AUTHOR]

Electrical properties of ferroelectric thin films depend on the quality of not only the ferroelectric thin layer but also the ferroelectric/electrode interfaces. In the present study, attempts were made to minimize the Pb depletion at the bottom electrode/ferroelectric interface in lead zirconate titanate ferroelectric thin films by adding a PbO interfacial layer using a chemical solution deposition method. The crystallographic structure of the PZT thin films with and without PbO layer were examined by X-ray diffraction. The microstructure of the thin film samples was characterized using optical microscope and atomic force microscope. [ABSTRACT FROM AUTHOR]

Abstract: A common design of piezoelectric microactuators adopts a membrane structure that consists of a base silicon structure, a layer of bottom electrode, a layer of piezoelectric thin film, and a layer of top electrode. In particular, the piezoelectric thin film is often made of lead–zirconate–titanate (PZT) for its high piezoelectric constants. When driven electrically, the PZT thin film extends or contracts flexing the membrane generating an out-of-plane displacement. For PZT thin-film microactuators, residual stresses are unavoidable from fabrication and can significantly reduce the actuation displacement. In this paper, the authors present a fourfold approach to address the issue of residual stresses. First, we demonstrate experimentally that two PZT thin-film actuators may present substantially different displacement and natural frequency even though dimensions of the two actuators are similar. Through a series of finite element analyses, we conclude that only residual stresses can produce such a significant frequency shift reducing the displacement of a PZT thin-film microactuator. Second, we measure the warping of the PZT thin-film actuator via interferometry to detect residual stresses. A simple calculation using shell theories indicates that the warping only causes a tiny shift in natural frequencies. Therefore, most of the degradation of actuator performance results from the nature that residual stresses are in-plane rather than the warping caused by the residual stresses. Third, we develop a vibration analysis to determine when residual stresses could significantly reduce actuator displacement. Fourth, we demonstrate two simple ways to mitigate the negative effects of residual stresses: poling at an elevated temperature and applying a DC bias voltage. [Copyright &y& Elsevier]

Abstract: In this paper, we propose innovative valveless pumping devices for microfluidic systems. The liquid in the microchannel was transported by generating a traveling wave on the channel wall, which was composed of a piezoelectric Pb(Zr,Ti)O3 (PZT) thin film actuator array. The PZT thin films were deposited on the silicon-on-insulator (SOI) substrates where microchannels, 200 and 500μm wide, were fabricated by deep reactive ion etching (DRIE). The displacement profiles and frequency response of the vibrating wall were measured using a laser Doppler vibrometer. The maximum displacements of the 200 and 500μm wide empty channels at 10Vpp were about 62 and 229nm, respectively. Minor displacement reductions were observed when the channel was filled with liquid, although the resonant frequencies dropped remarkably. On generating a traveling wave on the channel wall, clear liquid flow could be induced with a mean flow velocity of about 118 and 172μm/s for the 200 and 500μm wide channels, respectively. [Copyright &y& Elsevier]

Microactuators provide controlled motion and force for applications ranging from radio frequency switches to microfluidic valves. Large amplitude response in piezoelectric actuators requires amplification of the small strain, exhibited by the piezoelectric material, used in the construction of such actuators. This paper studies a uniflex microactuator that combines the strain amplification mechanisms of a unimorph and flexural motion to produce large displacement and blocking force. The design and fabrication of the proposed uniflex microactuator are described in detail. An analytical model is developed with three connected beams and a reflective symmetric boundary condition that predicts actuator displacement and blocking force as a function of the applied voltage. The model shows that the uniflex design requires appropriate parameter ranges, particularly the clearance between the unimorph and aluminum cap, to ensure that both the unimorph and flexural amplification effects are realized. With a weakened joint at the unimorphlcap interface, the model is found to predict the displacement and blocking force for the actuators fabricated in this work. [ABSTRACT FROM AUTHOR]