Search Results (23)

To facilitate the utility of field effect transistor (FET)-type sensors, achieving sensitivity enhancement beyond the Nernst limit is crucial. Thus, this study proposed a novel approach for the development of ferroelectric FETs (FeFETs) using lead zirconate titanate (PZT) ferroelectric films integrated with indium–tungsten oxide (IWO) channels synthesized via a cost-effective sol-gel process. The electrical properties of PZT-IWO FeFET devices were significantly enhanced through the strategic implementation of PZT film treatment by employing intentional annealing procedures. Consequently, key performance metrics, including the transfer curve on/off ratio and subthreshold swings, were improved. Moreover, unprecedented electrical stability was realized by eliminating the hysteresis effect during double sweeps. By leveraging a single-gate configuration as an FeFET transformation element, extended-gate (EG) detection methodologies for pH sensing were explored, thereby introducing a pioneering dimension to sensor architecture. A measurement paradigm inspired by plane gate work was adopted, and the proposed device exhibited significant resistive coupling, consequently surpassing the sensitivity thresholds of conventional ion-sensitive field-effect transistors. This achievement represents a substantial paradigm shift in the landscape of ion-sensing methodologies, surpassing the established Nernst limit (59.14 mV/pH). Furthermore, this study advances FeFET technology and paves the way for the realization of highly sensitive and reliable ion sensing modalities. Full article

Integration and miniaturization are the inevitable trends in the development of electronic devices. PZT and graphene are typical ferroelectric and carbon-based materials, respectively, which have been widely used in various fields. Achieving high-quality PZT/graphene heterogeneous integration and systematically studying its electrical properties is of great significance. In this work, we reported the characterization of a PZT film based on the sol–gel method. Additionally, the thickness of the PZT film was pushed to the limit size (~100 nm) by optimizing the process. The test results, including the remnant and leakage current, show that the PZT film is a reliable and suitable platform for further graphene-integrated applications. The non-destructive regulation of the electrical properties of graphene has been studied based on a domain-polarized substrate and strain-polarized substrate. The domain structures in the PZT film exhibit different geometric structures with ~0.3 V surface potential. The I–V output curves of graphene integrated on the surface of the PZT film exhibited obvious rectification characteristics because of p/n-doping tuned by an interfacial polarized electric field. In contrast, a ~100 nm thick PZT film makes it easy to acquire a larger strain gradient for flexural potential. The tested results also show a rectification phenomenon, which is similar to domain polarization substrate regulation. Considering the difficulty of measuring the flexural potential, the work might provide a new approach to assessing the flexural polarized regulation effect. A thinner ferroelectric film/graphene heterojunction and the polarized regulation of graphene will provide a platform for promoting low-dimension film-integrated applications. Full article

The direct growth of ferroelectric films onto flexible substrates has garnered significant interest in the advancement of portable and wearable electronic devices. However, the search for an optimized bottom electrode that can provide a large and stable remnant polarization is still ongoing. In this study, we report the optimization of an oxide-based LaNiO₃ (LNO) electrode for high-quality Pb(Zr_0.52Ti_0.48)O₃ (PZT) thick films. The surface morphology and electrical conductivity of sol-gel-grown LNO films on a fluorophlogopite mica (F-mica) substrate were optimized at a crystallization temperature of 800 °C and a film thickness of 120 nm. Our approach represents the promising potential pairing between PZT and LNO electrodes. While LNO-coated F-mica maintains stable electrical conductivity during 1.0%-strain and 10⁴-bending cycles, the upper PZT films exhibit a nearly square-like polarization–electric field behavior under those stress conditions. After 10⁴ cycles at 0.5% strain, the remnant polarization shows decreases as small as ~14%. Under flat (bent) conditions, the value decreases to just 81% (49%) after 10¹⁰ fatigue cycles and to 96% (85%) after 10⁵ s of a retention test, respectively. Full article

In response to the growing demand for high-sensitivity accelerometers in vector hydrophones, a piezoelectric MEMS accelerometer (PMA) was proposed, which has a four-cantilever beam integrated inertial mass unit structure, with the advantages of being lightweight and highly sensitive. A theoretical energy harvesting model was established for the piezoelectric cantilever beam, and the geometric dimensions and structure of the microdevice were optimized to meet the vibration pickup conditions. The sol-gel and annealing technology was employed to prepare high-quality PZT thin films on silicon substrate, and accelerometer microdevices were manufactured by using MEMS technology. Furthermore, the MEMS accelerometer was packaged for testing on a vibration measuring platform. Test results show that the PMA has a resonant frequency of 2300 Hz. In addition, there is a good linear relationship between the input acceleration and the output voltage, with V = 8.412a − 0.212. The PMA not only has high sensitivity, but also has outstanding anti-interference ability. The accelerometer structure was integrated into a vector hydrophone for testing in a calibration system. The results show that the piezoelectric vector hydrophone (PVH) has a sensitivity of –178.99 dB@1000 Hz (0 dB = 1 V/μPa) and a bandwidth of 20~1100 Hz. Meanwhile, it exhibits a good “8” shape directivity and consistency of each channel. These results demonstrate that the piezoelectric MEMS accelerometer has excellent capabilities suitable for use in vector hydrophones. Full article

This paper presents the fabrication and characterization of a biaxial MEMS (MicroElectroMechanical System) scanner based on PZT (Lead Zirconate Titanate) which incorporates a low-absorption dielectric multilayer coating, i.e., a Bragg reflector. These 2 mm square MEMS mirrors, developed on 8-inch silicon wafers using VLSI (Very Large Scale Integration) technology are intended for long-range (>100 m) LIDAR (LIght Detection And Ranging) applications using a 2 W (average power) pulsed laser at 1550 nm. For this laser power, the use of a standard metal reflector leads to damaging overheating. To solve this problem, we have developed and optimised a physical sputtering (PVD) Bragg reflector deposition process compatible with our sol-gel piezoelectric motor. Experimental absorption measurements, performed at 1550 nm and show up to 24 times lower incident power absorption than the best metallic reflective coating (Au). Furthermore, we validated that the characteristics of the PZT, as well as the performance of the Bragg mirrors in terms of optical scanning angles, were identical to those of the Au reflector. These results open up the possibility of increasing the laser power beyond 2W for LIDAR applications or other applications requiring high optical power. Finally, a packaged 2D scanner was integrated into a LIDAR system and three-dimensional point cloud images were obtained, demonstrating the scanning stability and operability of these 2D MEMS mirrors. Full article

Lead zircon titanate (PZT) composite films were advantageously prepared by a novel hybrid method of sol-gel and electrohydrodynamic jet (E-jet) printing. PZT thin films with thicknesses of 362 nm, 725 nm and 1092 nm were prepared on Ti/Pt bottom electrode via Sol-gel method, and then the PZT thick films were printed on the base of the PZT thin films via E-jet printing to form PZT composite films. The physical structure and electrical properties of the PZT composite films were characterized. The experimental results showed that, compared with PZT thick films prepared via single E-jet printing method, PZT composite films had fewer micro-pore defects. Moreover, the better bonding with upper and lower electrodes and higher preferred orientation of crystals were examined. The piezoelectric properties, dielectric properties and leakage currents of the PZT composite films were obviously improved. The maximum piezoelectric constant of the PZT composite film with a thickness of 725 nm was 69.4 pC/N, the maximum relative dielectric constant was 827 and the leakage current was reduced to 1.5 × 10⁻⁶A at a test voltage of 200V. This hybrid method can be widely useful to print PZT composite films for the application of micro-nano devices. Full article

High-quality, uniaxially oriented, and flexible PbZr_0.52Ti_0.48O₃ (PZT) films were fabricated on flexible RbLaNb₂O₇/BaTiO₃ (RLNO/BTO)-coated polyimide (PI) substrates. All layers were fabricated by a photo-assisted chemical solution deposition (PCSD) process using KrF laser irradiation for photocrystallization of the printed precursors. The Dion–Jacobson perovskite RLNO thin films on flexible PI sheets were employed as seed layers for the uniaxially oriented growth of PZT films. To obtain the uniaxially oriented RLNO seed layer, a BTO nanoparticle-dispersion interlayer was fabricated to avoid PI substrate surface damage under excess photothermal heating, and the RLNO has been orientedly grown only at around 40 mJ·cm⁻² at 300 °C. The prepared RLNO seed layer on the BTO/PI substrate showed very high (010)-oriented growth with a very high Lotgering factor (F(010) = 1.0). By using the flexible (010)-oriented RLNO film on BTO/PI, PZT film crystal growth was possible via KrF laser irradiation of a sol–gel-derived precursor film at 50 mJ·cm⁻² at 300 °C. The obtained PZT film showed highly (001)-oriented growth on the flexible plastic substrates with F(001) = 0.92 without any micro-cracks. The RLNO was only uniaxial-oriented grown at the top part of the RLNO amorphous precursor layer. The oriented grown and amorphous phases of RLNO would have two important roles for this multilayered film formation: (1) triggering orientation growth of the PZT film at the top and (2) the stress relaxation of the underneath BTO layer to suppress the micro-crack formation. This is the first time that PZT films have been crystallized directly on flexible substrates. The combined processes of photocrystallization and chemical solution deposition are a cost-effective and highly on-demand process for the fabrication of flexible devices. Full article

PbZr_0.35Ti_0.65O₃ (PZT), PbZrO₃ (PZO), and PZT/PZO ferroelectric/antiferroelectric multilayer films were prepared on a Pt/Ti/SiO₂/Si substrate using the sol–gel method. Microstructures and physical properties such as the polarization behaviors, leakage current, dielectric features, and energy-storage characteristics of the three films were systematically explored. All electric field-dependent phase transitions, from sharp to diffused, can be tuned by layer structure, indicated by the polarization, shift current, and dielectric properties. The leakage current behaviors suggested that the layer structure could modulate the current mechanism, including space-charge-limited bulk conduction for single layer films and Schottky emission for multilayer thin films. The electric breakdown strength of a PZT/PZO multilayer structure can be further enhanced to 1760 kV/cm, which is higher than PZT (1162 kV/cm) and PZO (1373 kV/cm) films. A recoverable energy-storage density of 21.1 J/cm³ was received in PZT/PZO multilayers due to its high electric breakdown strength. Our results demonstrate that a multilayer structure is an effective method for enhancing energy-storage capacitors. Full article

Polarization switching in ferroelectric films is exploited in many applications, such as non-volatile memories and negative capacitance field affect transistors. This can be inhomogeneous or homogeneous, depending on if ferroelectric domains are forming or not during the switching process. The relation between the polarization switching, the structural quality of the films and the negative capacitance was not studied in depth. Here, Pb(Zr_0.2Ti_0.8)O₃ (PZT) layers were deposited by pulse laser deposition (PLD) and sol-gel (SG) on single crystal SrTiO₃ (STO) and Si substrates, respectively. The structural quality was analyzed by X-ray diffraction and transmission electron microscopy, while the electric properties were investigated by performing hysteresis, dynamic dielectric measurements, and piezo-electric force microscopy analysis. It was found that the PZT layers grown by PLD on SRO/STO substrates are epitaxial while the layers deposited by SG on Pt/Si are polycrystalline. The polarization value decreases as the structure changes from epitaxial to polycrystalline, as well as the magnitude of the leakage current and of the differential negative capacitance, while the switching changes from homogeneous to inhomogeneous. The results are explained by the compensation rate of the depolarization field during the switching process, which is much faster in epitaxial films than in polycrystalline ones. Full article

Compared to aluminum nitride (AlN) with simple stoichiometry, lead zirconate titanate thin films (PZT) are the other promising candidate in advanced micro-electro-mechanical system (MEMS) devices due to their excellent piezoelectric and dielectric properties. The fabrication of PZT thin films with a large area is challenging but in urgent demand. Therefore, it is necessary to establish the relationships between synthesis parameters and specific properties. Compared to sol-gel and pulsed laser deposition techniques, this review highlights a magnetron sputtering technique owing to its high feasibility and controllability. In this review, we survey the microstructural characteristics of PZT thin films, as well as synthesis parameters (such as substrate, deposition temperature, gas atmosphere, and annealing temperature, etc.) and functional proper-ties (such as dielectric, piezoelectric, and ferroelectric, etc). The dependence of these influential factors is particularly emphasized in this review, which could provide experimental guidance for researchers to acquire PZT thin films with expected properties by a magnetron sputtering technique. Full article

This paper proposes an electric field microsensor (EFM) with mutual shielding electrodes. Based on the charge-induction principle, the EFM consists of fixed electrodes and piezoelectric-driving vertically-movable electrodes. All the fixed electrodes and movable electrodes work as both sensing electrodes and shielding electrodes. In other words, all the fixed and movable electrodes are sensing electrodes, and they are mutually shielding electrodes simultaneously. The movable electrodes are driven to periodically modulate the electric field distribution at themselves and the fixed electrodes, and the induced currents from both movable and fixed electrodes are generated simultaneously. The electrode structure adopts an interdigital structure, and the EFM has been simulated by finite element methods. Simulation results show that, since the sensing area of this EFM is doubled, the variation of induced charge is twice, and therefore the output signal of the sensor is increased. The piezoelectric material, lead zirconate titanate (PZT), is prepared by the sol–gel method, and the microsensor chip is fabricated. Full article

In this paper, a piezoelectric wave-energy converter (PWEC), consisting of a buoy, a frequency up-conversion mechanism, and a piezoelectric power-generator component, is developed. The frequency up-conversion mechanism consists of a gear train and geared-linkage mechanism, which converted lower frequencies of wave motion into higher frequencies of mechanical motion. The slider had a six-period displacement compared to the wave motion and was used to excite the piezoelectric power-generation component. Therefore, the operating frequency of the piezoelectric power-generation component was six times the frequency of the wave motion. The developed, flexible piezoelectric composite films of the generator component were used to generate electrical voltage. The piezoelectric film was composed of a copper/nickel foil as the substrate, lead–zirconium–titanium (PZT) material as the piezoelectric layer, and silver material as an upper-electrode layer. The sol-gel process was used to fabricate the PZT layer. The developed PWEC was tested in the wave flume at the Tainan Hydraulics Laboratory, Taiwan (THL). The maximum height and the minimum period were set to 100 mm and 1 s, respectively. The maximum voltage of the measured value was 2.8 V. The root-mean-square (RMS) voltage was 824 mV, which was measured through connection to an external 495 kΩ resistive load. The average electric power was 1.37 μW. Full article

We reported a sandwich structured Pb(Zr_0.4Ti_0.6)O₃/BaZr_0.2T_i0.8O₃/Pb(Zr_0.4Ti_0.6)O₃ (PZT/BZT/PZT) film fabricated by using the sol–gel method, which was dense and uniform with a unique perovskite structure. The PZT/BZT/PZT films displayed high dielectric constants up to 1722.45 at the frequency of 10 kHz. Additionally, the enhanced energy storage density of 39.27 J·cm⁻³ was achieved at room temperature and 2.00 MV/cm, which was higher than that of the individual BaZr_0.2T_i0.8O₃ film (21.28 J·cm⁻³). Furthermore, the energy storage density and efficiency of PZT/BZT/PZT film increased slightly with the increasing temperature from −140 °C to 200 °C. This work proves the feasibility and effectiveness of a sandwich structure in improving dielectric, leakage, and energy storage performances, providing a new paradigm for high-energy–density dielectrics applications. Full article

As a promising functional material, ferroelectric Pb(Zr_xTi_1−x)O₃ (PZT) are widely used in many optical and electronic devices. Remarkably, as the film thickness decreases, the materials’ properties deviate gradually from those of solid materials. In this work, multilayered PZT thin films with different thicknesses are fabricated by Sol-Gel technique. The thickness effect on its microstructure, ferroelectric, and optical properties has been studied. It is found that the surface quality and the crystalline structure vary with the film thickness. Moreover, the increasing film thickness results in a significant increase in remnant polarization, due to the interfacial layer effect. Meanwhile, the dielectric loss and tunability are strongly dependent on thickness. In terms of optical properties, the refractive index of PZT films increase with the increasing thickness, and the photorefractive effect are also influenced by the thickness, which could all be related to the film density and photovoltaic effect. Besides, the band gap decreases as the film thickness increases. This work is significant for the application of PZT thin film in optical and optoelectronic devices. Full article

The composition of fine-ground lead zirconate-titanate powder Pb(Zr_0.52Ti_0.48)O₃, suspended in PZT and bismuth titanate (BiT) solutions, is deposited on the curved surface of IN718 and IN738 nickel-based supper alloy substrates up to 100 µm thickness. Photochemical metal organic and infiltration techniques are implemented to produce smooth, semi-dense, and crack-free random orientated thick piezoelectric films as piezo-sensors, free of any dopants or thickening polymers. Every single layer of the deposited films is heated at 200 °C with 10 wt.% excess PbO, irradiated by ultraviolet lamp (365 nm, 6 watt) for 10 min, pyrolyzed at 400 °C, and subsequently annealed at 700 °C for one hour. This process is repeated successively until reaching the desired thickness. Au and Pt thin films are deposited as the bottom and top electrodes using evaporation and sputtering methods, respectively. PZT/PZT and PZT/BiT composite films are then characterized and compared to similar PZT and BiT thick films deposited on the similar substrates. The effect of the composition and deposition process is also investigated on the crystalline phase development and microstructure morphology as well as the dielectric, ferroelectric, and piezoelectric properties of piezo-films. The maximum remnant polarization of P_r = 22.37 ± 0.01, 30.01 ± 0.01 µC/cm², the permittivity of ε_r = 298 ± 3, 566 ± 5, and piezoelectric charge coefficient of d₃₃ = 126, 148 m/V were measured versus the minimum coercive field of E_c = 50, 20 kV/cm for the PZT/PZT and PZT/BiT thick films, respectively. The thick film piezo-sensors are developed to be potentially used at frequency bandwidth of 1–5 MHz for rotary structural health monitoring and also in other industrial or medical applications as a transceiver. Full article