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Domain switching not only exhibits a great effect on piezoelectric performance, but also serves as foundation of some ferroelectric applications, such as ferroelectric nonvolatile memories and nonlinear optical devices. Therefore, a thorough understanding in the process and mechanism of domain switching is of vital significance. In this paper, we observed the process of domain switching under electric field by controlling poling conditions. The domain structures, polarization orientation, and piezoelectric performance of K 0.52 Na 0.48 NbO 3 single crystals poled at different temperatures and electric fields were investigated. We found that the polarization-rotation in poling process of the crystals occurs in steps and along a specific conversion path: [ 1 ¯ 01] - [011] - [ 1 ¯ 10]. Furthermore, poling under specific conditions can construct specific domains, which can be used in optical-function devices and may significantly promote the design of new generation ferroelectric memory devices. [ABSTRACT FROM AUTHOR]

Flexible electronics strongly demand the integration of flexible and large‐scale multifunctional oxides. BiFeO3 is one of the most essential multifunctional oxides that could be used in memories, logics, sensors, and actuators. Recently, freestanding single‐crystalline BiFeO3 membranes exhibited superior elasticity and flexibility. However, fabrication and integration of large‐scale freestanding BiFeO3 membranes into flexible electronics remain elusive. In this study, inch‐scale freestanding single‐crystalline BiFeO3 membranes are fabricated with assistance from a water‐soluble sacrificial layer. To transfer flat and crack‐free membranes, all the existing methods are first followed but fail. Then the study introduces a temporary supporting Cu layer on the surface of the as‐grown SiTiO3/Sr3Al2O6/(SrRuO3/)BiFeO3 heterostructure and successfully obtains full and crack‐free 5 mm × 5 mm freestanding membranes on various substrates. The residual strain within the heterostructure releases gradually under the protection of the Cu layer. The freestanding BiFeO3 membranes are relatively uniform among different regions and exhibit good dielectric, ferroelectric, and ferromagnetic properties. Finally, flexible ferroelectric photovoltaic devices are patterned based on those BiFeO3 membranes, and they have open circuit voltage and short circuit current density up to −0.25 ± 0.03 V and 0.82 ± 0.09 µA cm−2, respectively. [ABSTRACT FROM AUTHOR]

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The polarization switching pathway plays a key role in deciding the magnitudes of the spontaneous polarization and the coercive electric field, which can be used to realize controllable ferroelectric properties. In this paper, by first-principles calculations, we reveal how the spontaneous polarization (Ps) and the switching barrier (Eb) of orthorhombic HfO2 (o-HfO2) respond to various lattice strains depending on two kinds of switching pathways, i.e., the shift-across (SA) pathway and the shift-inside pathway. It is revealed that the existence of the two pathways is most likely dependent on the interface termination of o-HfO2, and the SA pathway exhibits higher critical values of both Ps and Eb. By applying lattice strains on o-HfO2 (001) and (010) planes, a ferroelectric–paraelectric phase transition from the polar Pca21 to the nonpolar Pbcn can be observed. Importantly, the variation trends of Ps and Eb under the same lattice strains are found to be highly different depending on the switching pathways. However, by carefully designing the interfacial tail atoms, strain engineering can efficiently improve Eb and Ps for both pathways in o-HfO2 films. Our work uncovers the mechanisms of the switching pathways and opens a new avenue for preparing high-performance ferroelectric devices using strain engineering. [ABSTRACT FROM AUTHOR]

The polarization switching pathway plays a key role in deciding the magnitudes of the spontaneous polarization and the coercive electric field, which can be used to realize controllable ferroelectric properties. In this paper, by first-principles calculations, we reveal how the spontaneous polarization (Ps) and the switching barrier (Eb) of orthorhombic HfO2 (o-HfO2) respond to various lattice strains depending on two kinds of switching pathways, i.e., the shift-across (SA) pathway and the shift-inside pathway. It is revealed that the existence of the two pathways is most likely dependent on the interface termination of o-HfO2, and the SA pathway exhibits higher critical values of both Ps and Eb. By applying lattice strains on o-HfO2 (001) and (010) planes, a ferroelectric–paraelectric phase transition from the polar Pca21 to the nonpolar Pbcn can be observed. Importantly, the variation trends of Ps and Eb under the same lattice strains are found to be highly different depending on the switching pathways. However, by carefully designing the interfacial tail atoms, strain engineering can efficiently improve Eb and Ps for both pathways in o-HfO2 films. Our work uncovers the mechanisms of the switching pathways and opens a new avenue for preparing high-performance ferroelectric devices using strain engineering. [ABSTRACT FROM AUTHOR]

The fabrication of epitaxial ferroelectric materials on Si substrates is key to the design of superior ferroelectric devices for applications involving microelectromechanical systems (MEMS). The domain structures of epitaxial PbTiO3 films grown on Si substrates with an epitaxial SrTiO3 buffer layer were investigated, especially in terms of film thickness dependence. The low thermal expansion coefficient of Si was found to affect the volume fraction of (001)-oriented domains not only in relatively thick film regions but also in the thinner ones. Compared with the PbTiO3 films deposited on SrTiO3 substrates, (100)-oriented domains were observed in films as thin as 18 nm, notwithstanding the strong misfit strain induced by the substrate. Moreover, the saturated volume fraction of the (001)-oriented domain was smaller than that of PbTiO3 on SrTiO3. Thermal strain plays a critical role in determining domain structures and is, therefore, expected to govern the electric properties of films useful in MEMS devices. [ABSTRACT FROM AUTHOR]

2D ferroelectric materials are promising for designing low-dimensional memory devices. Here, we explore strain-tunable ferroelectric properties of group-IV monochalcogenides MX (M = Ge , Sn; X = S , Se) and their potential application in lateral field tunnel junction devices. We find that these monolayers have in-plane ferroelectricity, with their ferroelectric parameters being on par with other known 2D ferroelectric materials. Among SnSe, SnS, GeSe, and GeS, we find that GeS has the best ferroelectric parameters for device applications, which can be improved further by applying uniaxial tensile strain. We use the calculated ferroelectric properties of these materials to study the tunneling electroresistance (TER) of a 4 nm device based on a lateral ferroelectric tunnel junction. We find a substantial TER ratio of 10 3 – 10 5 in the devices based on these materials, which can be further improved up to a factor of 40 on the application of tensile strain. [ABSTRACT FROM AUTHOR]

With the development of artificial intelligence technology, it remains a challenge to improve the resistive switching performance of next-generation nonvolatile ferroelectric memristor device (FMD). Here, we report an epitaxial Na0.5Bi0.5TiO3 ferroelectric memristor device (NBT-FMD) with temperature sensing. The NBT epitaxial films with strong polarization strength and suitable oxygen vacancy concentration were obtained by temperature adjustment (700 °C). In addition, the function of the spiking-time-dependent plasticity and paired-pulse facilitation is simulated in ferroelectric memristor devices of Pt/NBT/SrRuO3 (SRO)/SrTiO3 (STO). More importantly, we have designed a neuronal circuit to confirm that NBT-FMD can serve as temperature receptors on the human skin, paving the way for bio-inspired application. [ABSTRACT FROM AUTHOR]

Improving the endurance performance for hafnia-based ferroelectric thin films and devices is of considerable significance from both scientific and technological perspectives. Here, we obtained robust ferroelectricity in Hf0.5Zr0.5O2 (HZO) thin films without the need of the confinement from top electrodes by systematically optimizing the conditions and parameters for the post-deposition annealing (PDA) process. Compared with the post-metallization annealing (PMA) process, PDA is found to markedly improve the ferroelectric endurance performance. In particular, wake-up-free ferroelectric HZO thin films with an exceptional endurance performance (∼3 × 1010 cycles) are obtained by PDA processing conducted under an oxygen atmosphere, which is attributed to the suppression of oxygen deficiency in the HZO thin films and the inhibition of interfacial reaction layer that inevitably forms during annealing treatment for PMA processing. Our work offers insight into improving ferroelectricity and endurance for hafnia-based ferroelectric materials and devices. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferroelectrics has emerged as a promising building block for nonvolatile memory devices. In this work, we demonstrate the out-of-plane ferroelectricity of 2D CuCrP2S6 (CCPS) at the room temperature and the switchable diode effect in 2D CCPS-based ferroelectric nanodevices. The spontaneous out-of-plane ferroelectric polarization switching and hysteresis loops are directly evidenced by the piezoresponse force microscopy. The intrinsic ferroelectricity originates from the non-centrosymmetric structure of 2D CCPS, which is confirmed by optical second-harmonic generation technique. A ferroelectric tunnel junction was built up by using 2D CCPS as a function layer. The observed diode-like forward rectification effect of CCPS diode is opposite to the direction of remnant polarization, which is attributed to the ferroelectric polarization modulation of Schottky barrier. Our work highlights the great potential of 2D CCPS in ultrathin ferroelectric memory device and motivates the development of multifunctional nanodevices. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) ferroelectrics has emerged as a promising building block for nonvolatile memory devices. In this work, we demonstrate the out-of-plane ferroelectricity of 2D CuCrP2S6 (CCPS) at the room temperature and the switchable diode effect in 2D CCPS-based ferroelectric nanodevices. The spontaneous out-of-plane ferroelectric polarization switching and hysteresis loops are directly evidenced by the piezoresponse force microscopy. The intrinsic ferroelectricity originates from the non-centrosymmetric structure of 2D CCPS, which is confirmed by optical second-harmonic generation technique. A ferroelectric tunnel junction was built up by using 2D CCPS as a function layer. The observed diode-like forward rectification effect of CCPS diode is opposite to the direction of remnant polarization, which is attributed to the ferroelectric polarization modulation of Schottky barrier. Our work highlights the great potential of 2D CCPS in ultrathin ferroelectric memory device and motivates the development of multifunctional nanodevices. [ABSTRACT FROM AUTHOR]

Synapses play a vital role in information processing, learning, and memory formation in the brain. By emulating the behavior of biological synapses, electronic synaptic devices hold the promise of enabling high‐performance, energy‐efficient, and scalable neuromorphic computing. Ferroelectric memristive devices integrate the characteristics of both ferroelectric and memristive materials and present a far‐reaching potential as artificial synapses. Here, it is reported on a new ferroelectric device on silicon, a field‐effect memristor, consisting of an epitaxial ultrathin ferroelectric Hf0.5Zr0.5O2 film sandwiched between an epitaxial highly doped oxide semiconductor SrTiO3‐δ and a top metal. Upon a low voltage of less than 2 V, the field‐effect modulation in the semiconductor enables to access multiple states. The device works in a large time domain ranging from milliseconds down to tens of nanoseconds. By gradually switching the polarization by identical pulses, the ferroelectric diode devices can dynamically adjust the synaptic strength to mimic short‐ and long‐term memory plasticity. Ionic contributions due to redox processes in the oxide semiconductor beneficially influence the device operation and retention. [ABSTRACT FROM AUTHOR]

Neuromorphic computing systems are based on new architecture inspired by biological learning behavior and biological structure to overcome the shortcomings of the von Neumann system, such as high energy consumption and generation of excessive redundant data. However, common synaptic‐device designs are still need to carry an external power source, which is detrimental to both the miniaturization of smart devices and the further reduction of energy consumption. Therefore, self‐powered optoelectronic synapses hold great promise for achieving energy‐efficient artificial intelligence applications. Given the advantages of heterogeneous integration and ferroelectric performance, the 2D ferroelectric In2Se3 has become a typical candidate material for biological synaptic devices and neuromorphic computing. Although, various structures of ferroelectric synaptic devices are developed, most of which are controlled by optical or electrical pulses, hardly any reports discuss the operation in self‐powered mode. In this work, an In2Se3/MoS2 ferroelectric lateral heterojunction‐type optoelectronic synaptic device is fabricated to mimic biological synaptic functions in voltage mode or self‐driven mode. In addition, two simplified image pre‐processing methods based on device arrays are shown to improve the recognition accuracy of a back‐end neural network. The proposed approach suggests a new route for designing and applying high‐performance synaptic devices. [ABSTRACT FROM AUTHOR]

Sr2Bi4Ti5O18 is one of the promising candidates for ferroelectric nonvolatile random access memory device applications. Albeit, this ceramic material is not suitable for certain ferroelectric device applications because of the merits and demerits associated with this material. Solid‐solution or composite ceramics in bulk configuration is the better choice to overcome the drawbacks associated with the individual compounds. Concurrently, solid‐solution of functional electro‐ceramics comprising Aurivillius family‐based lead‐free bismuth‐layered structured ceramics (1 − x) Sr2Bi4Ti5O18 (SBT) and x mol% of ilmenite structured ZnSnO3 (ZS) (where x = 0, 5, 10, and 20 mol%) were synthesized via conventional solid‐state reaction route to investigate the effect of ZS on the physical properties of SBT. X‐ray diffraction diffractograms revealed that a single phase was formed maximum up to 5 mol% of ZS in SBT and scanning electron microscopy studies suggested platelike microstructure of the samples. Intriguingly, positive‐up and negative‐down results indicated that the true switchable polarization for the 10 mol% ZS in SBT (10.87 μC/cm2), 33% higher than that of pure SBT ceramics in addition to the lower leakage current density and enhanced dielectric response in the SBT–ZS samples. The observed enhancement in electrical characteristics of SBT–ZS composite ceramics compared to pure SBT highlights the decisive role played by the ZS in lowering the thermodynamic barrier resulting in ease of polarization switching and mitigating the leakage current of SBT ceramics. [ABSTRACT FROM AUTHOR]

Ferroelectric HfO2 and ZrO2-based materials are promising candidates for next-generation ferroelectric devices, but their characterization is challenging due to complex factors such as crystal phases, degradation mechanisms, and local inhomogeneities. In this work, we propose a novel nanosized positive-up-negative-down (PUND) method to assess the ferroelectric response of doped-HfO2. This method is based on actual current probing and is immune to most electrostatic artifacts that plague other electrical atomic force microscopy (AFM) techniques. We demonstrate the PUND method's ability to induce ferroelectric switching in Si-doped HfO2 and investigate the distinctive PUND response obtained for individual grains. We also extract the polarization charge based on a direct estimate of the tip–sample contact area. The proposed PUND method is a significant innovation as it is a method to combine the high spatial resolution of AFM with the immunity to electrostatic artifacts of current probing. This makes it a powerful tool for studying ferroelectric materials at the nanoscale, where local inhomogeneities and other effects can have a significant impact on their behavior. The PUND method is also notable for its ability to extract polarization charge based on a direct estimate of the tip–sample contact area. This is a significant improvement over previous methods, which often relied on indirect or approximate estimates of the contact area. Overall, the PUND method is a novel and innovative technique that offers significant advantages for the characterization of ferroelectric materials at the nanoscale. It is expected to have a major impact on the research and development of next-generation ferroelectric devices. [ABSTRACT FROM AUTHOR]

Neuromorphic devices based on ferroelectric resistive switching (RS) effects are promising to simulate the information recognition and memory of the human brain. However, the high power of RS elements in crossbar arrays is still an issue, limiting the neuromorphic applications. Here, we propose a domain-modified engineering for low-power RS in ferroelectric diodes by locally introducing relaxor ferroelectric units to lower domain switching barriers. A low-power RS of ∼ 70 μW, with large OFF/ON resistance ratio and high endurance, is achieved in Au/0.8BaTiO3-0.1Ba0.7Sr0.3TiO3-0.1BaTi0.7Zr0.3O3/Pt diodes, which is about 48.5% lower than that in Au/BaTiO3/Pt diodes. The interaction between macrodomains is depressed by domain modification engineering, lowering domain switching barriers, thereby operating voltage and power are significantly modulated. Meanwhile, good nonvolatility is obtained since the remanent polarization is partially maintained by the initial macrodomains and its decrease is slowed down by the relaxor units. This work provides a strategy to lower RS power by domain modification engineering for developing memristors and neuromorphic computing devices. [ABSTRACT FROM AUTHOR]

How and why the reliability of ferroelectric HfO2‐ and HZO (Hf0.5Zr0.5O2)‐based memory devices strongly depends on the choice of electrode materials is currently under intense discussion. Interface conditions such as band alignment, defect formation, and doping are recognized as decisive and interrelated parameters, but a unified picture of the physical mechanisms is still missing. Here, two opposite scenarios of band alignment are found in TiN/HZO/TiN and IrO2/HZO/IrO2 using hard X‐ray photoelectron spectroscopy, revealing on the one hand the conditions for a stable device performance, and the origin of their degradation on the other. As a key difference, TiN electrodes scavenge oxygen from the HZO, while IrO2 electrodes supply it. Considering the electronic doping limit of HfO2, a key condition for the stability of ferroelectric devices can be identified: The alignment of the charge neutrality levelwith respect to the metallic Fermi level, which is pinned by the doping limit. Stable device performance can only be achieved for oxygen‐deficient HfO2‐based interfaces, where the Fermi level of the metal electrode is close to the conduction band of the ferroelectric insulator. This empirical model explains the fatigue behavior of HfO2‐based capacitors using either oxygen‐scavenging TiN or oxygen‐supplying IrO2 electrodes. [ABSTRACT FROM AUTHOR]

Ferroelectric domain walls (DWs) are spatial interfaces separating domains with distinct polarization orientations. Among these DWs, some can carry bound charges and display metallic-like conductivity. The feature is highly of interest for future nanoelectronics. However, the inherent instability of charged domain walls (CDWs) has posed a critical challenge for their experimental exploration. This Letter reports the head-to-head (HH) and tail-to-tail (TT) 180 ° CDWs within the context of ferroelectric hafnium oxide. We proposed that oxygen vacancy is a crucial factor stabilizing the periodic CDWs. Through meticulous first-principles calculations, we elaborated on the intricate properties of these CDWs, including their polarization profiles, and potential and charge distributions. Furthermore, we calculated the energy barrier for layer-by-layer propagation of a HH wall and carefully discussed the migration of a TT wall with oxygen vacancy. Our study can shed more light onto the characteristics of CDWs and their implications to hafnia-based ferroelectric devices. [ABSTRACT FROM AUTHOR]

Flexible Si-based Hf0.5Zr0.5O2 (HZO) ferroelectric devices exhibit numerous advantages in the internet of things (IoT) and edge computing due to their low-power operation, superior scalability, excellent CMOS compatibility, and light weight. However, limited by the brittleness of Si, defects are easily induced in ferroelectric thin films, leading to ferroelectricity degradation and a decrease in bending limit. Thus, a solution involving the addition of an ultra-thin Al buffer layer on the back of the device is proposed to enhance the bending limit and preserve ferroelectric performance. The device equipped with an Al buffer layer exhibits a 2Pr value of 29.5 μC/cm2 (25.1 μC/cm2) at an outward (inward) bending radius of 5 mm, and it experiences a decrease to 22.1 μC/cm2 (16.8 μC/cm2), even after 6000 bending cycles at a 12 mm outward (inward) radius. This outstanding performance can be attributed to the additional stress generated by the dense Al buffer layer, which is transmitted to the Si substrate and reduces the bending stress on the Si substrate. Notably, the diminished bending stress leads to a reduced crack growth in ferroelectric devices. This work will be beneficial for the development of flexible Si-based ferroelectric devices with high durability, fatigue resistance, and functional mobility. [ABSTRACT FROM AUTHOR]

This work systematically investigates the impact of a pre-annealed ZrO2 interfacial layer on the ferroelectric behavior of Hf0.5Zr0.5O2 (HZO) capacitors. The remanent polarization (2Pr) value of HZO capacitors, including configurations such as W/HZO/TiN/p+ Si, W/HZO/(pre-annealed) ZrO2/TiN/p+ Si, W/HZO/SiO2/TiN/p+ Si, and W/HZO/SiO2/p+ Si, exhibits significant variations. The W/HZO/(pre-annealed) ZrO2/TiN/p+ Si capacitor demonstrates superior ferroelectric performance, with a 2Pr value of ~32 µC/cm2. Furthermore, by optimizing the thickness combination of HZO and the pre-annealed ZrO2 interfacial layer, a capacitor with a 10 nm HZO and 2 nm ZrO2 achieves the largest 2Pr value. The pre-annealing process applied to ZrO2 is found to play a very important role in inducing the orthorhombic phase and thus enhancing ferroelectricity. This enhancement is attributed to the pre-annealed 2 nm ZrO2 interfacial layer acting as a structural guide for the subsequent HZO orthorhombic phase, thereby improving the ferroelectric performance of HZO capacitors. These findings provide a comprehensive explanation and experimental verification of the impact of pre-annealed ZrO2 on ferroelectric devices, offering novel insights for the optimization of ferroelectric properties. [ABSTRACT FROM AUTHOR]

In this study, the domain switching mechanism of ferroelectric HZO thin films is investigated by analyzing the bulk charge of a graphene field‐effect transistor with an HZO dielectric device by using a pulsed IV measurement method. The domain switching speed, which is generally difficult to observe from a typical DC‐IV analysis of metal‐oxide‐semiconductor field‐effect transistors using a parameter analyzer, is investigated via the fast pulsed IV analysis method. Based on the measurements, most of the ferroelectric HZO domains are fast switched within 100 ns; however, domains that require a longer switching time in the order of 1 ms are also identified. Short pulses can be continuously applied to minimize the influence of other domains that are not switched by the switched domain. The feasibility of partial switching of the domains, which can be utilized for the multi‐functional operation of ferroelectric HZO devices, is observed. The results suggest that further investigation of the physical properties of slow‐switching domains is necessary to develop future synaptic array applications. [ABSTRACT FROM AUTHOR]

Epitaxial strain plays an extraordinary role in the formation, evolution, and phase transition of topological domain structures in nanoscale ferroelectrics. Unfortunately, how vortex switching reacts to misfit strain in epitaxial nanodots remains unclear. Based on phase-field simulations, the reversal of vortex chirality in an epitaxial triangular nanodot induced by a uniform electric field applied along various directions is systematically investigated as a function of misfit strain. The results indicate that three basic types of vortex switching exist in an epitaxial triangular nanodot: type I under compressive strain, type II under tensile strain, and a narrow transition type with the characteristics of types I and II. The results show that misfit strain plays a crucial role in determining the type of vortex switching. This work, thus, clarifies the role of misfit strain and could be conducive to facilitating the mechanical manipulation of ferroelectric nanoelectronic devices. [ABSTRACT FROM AUTHOR]

Mastering the variations in the stability of a polarization vortex is fundamental for the development of ferroelectric devices based on polarization vortex domain structures. Some phase field simulations were conducted on PbTiO3 nanofilms with an initial polarization vortex under uniaxial tension or compression to investigate the conditions of vortex instability and the effects of aspect ratio of nanofilms and temperature on them. The instability of a polarization vortex is strongly dependent on aspect ratio and temperature. The critical compressive stress increases with decreasing aspect ratio under the action of compressive stress. However, the critical tensile stress first decreases and then increases with decreasing aspect ratio, then continues to decrease. There are two inflection points in the curve. In addition, an elevated temperature makes both the critical tensile and compressive stresses decline, and will also cause the aspect ratio corresponding to the inflection point to decrease. These are very important for the design of promising nano-ferroelectric devices based on polarization vortices to improve their performance while maintaining storage density. [ABSTRACT FROM AUTHOR]

Constitutive modeling of ferroelectrics is a challenging task, spanning physical processes on different scales from unit cell switching and domain wall motion to polycrystalline behavior. The condensed method (CM) is a semi-analytical approach, which has been efficiently applied to various problems in this context, ranging from self-heating and damage evolution to energy harvesting. Engineering applications, however, inevitably require the solution of arbitrary boundary value problems, including the complex multiphysical constitutive behavior, in order to analyze multifunctional devices with integrated ferroelectric components. The well-established finite element method (FEM) is commonly used for this purpose, allowing sufficient flexibility in model design to successfully handle most tasks. A restricting aspect, especially if many calculations are required within, e.g., an optimization process, is the computational cost which can be considerable if two or even more scales are involved. The FEM–CM approach, where a numerical discretization scheme for the macroscale is merged with a semi-analytical methodology targeting at material-related scales, proves to be very efficient in this respect. [ABSTRACT FROM AUTHOR]

High-density ferroelectric BiFeO3 (BFO) nanodot arrays were developed through template-assisted tailoring of epitaxial thin films. By combining piezoresponse force microscopy (PFM) and Kelvin probe force microscopy (KPFM) imaging techniques, we found that oxygen vacancies in nanodot arrays can be transported in the presence of an electric field. Besides triple-center domains, quadruple-center domains with different vertical polarizations were also identified. This was confirmed by combining the measurements of the domain switching and polarization vector distribution. The competition between the accumulation of mobile charges, such as oxygen vacancies, on the interface and the geometric constraints of nanodots led to the formation of these topological domain states. These abnormal multi-center topological defect states pave the way for improving the storage density of ferroelectric memory devices. [ABSTRACT FROM AUTHOR]

We present the modeling and analysis of electrical coupling in a hysteretic deformable mirror with 2D memory piezoactuators, which are made of a purposely designed piezomaterial sandwiched between electrodes arranged crosswise and actuated by a multiplexing approach. Using a modified Miller model to describe the memory effect which is based on the ferroelectric domain switching processes, the proposed framework is used to simulate the electric-field dependence of the strain in the piezoelectric material that exhibits asymmetric butterfly loops with remnant deformation through the finite element method. The desired butterfly memory effect in the material is obtained by modifying the saturated dipole polarization curve in the Miller model. The proposed method allows us to numerically investigate the electrical coupling between actuators in more detail and correspondingly understand their influence to the mirror facesheet. [ABSTRACT FROM AUTHOR]

Imprint, the preferential orientation of the polarization of a ferroelectric device subjected to elevated temperatures, is a primary reliability concern afflicting data retention in ferroelectric RAM. In this paper, we demonstrate Preisach-based hysteresis modeling, which can be used to predict imprint behavior in ferroelectric thin films. A method was developed for capturing imprint in the context of a Preisach model and a numerical approach for evaluating the Preisach distribution was expanded upon. Interpolation and curve fitting were used to make predictions of the Preisach distributions of imprinted ferroelectric hafnium zirconium oxide devices after short-duration bakes at 23–260 °C and long-term bakes at 85 and 125 °C. In the case of long-term bakes, imprint-induced coercive shifts were modeled as shifts in the derivative of the top and bottom hysteretic polarization curves. The shift in the curves is modeled by fitting experimental data to a commonly used empirically logarithmic relationship reported in the literature. Simulations give remanent polarizations and coercive fields within <5.0 μC/cm2 and 0.1 V, respectively, of the raw data average. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations based on the anisotropic shell model with the first-principles parameters are performed to investigate the void-mediated polarization vortex domain switching in compressed BaTi O 3 nanofilms. When a unit-cell-size void is located at the nanofilm center, the polarization configuration is in a single-vortex state instead of a multi-vortex state. For different void length fractions along the [100] lattice orientation, a cylindrical vortex is formed around the void while a few small vortexes nucleate closely above and/or below the void. With increasing void area fraction in the [100] plane, the vortex around the void gradually switches from clockwise to counterclockwise. Both the void shape and orientation have important effects on the vortex domain switching. A void near the model center tends to induce a clockwise vortex around it, a void in the lower left region of model to motivate a counterclockwise vortex, but a void in other locations to induce a closure domain with different switching degrees. In addition, it is found that the degree of closure domain switching could be kept if a void changes its location only in a small area. These observations should be instructive for the design and application of ferroelectric devices. [ABSTRACT FROM AUTHOR]

Investigation of the polarization switching mechanism in ferroelectric hafnium zirconium oxide (HZO) film is of great importance for developing high-quality ferroelectric memory devices. Recently, several works have been reported to describe the switching process of polycrystalline HZO film using the inhomogeneous field mechanism (IFM) model. However, no report has recorded the effect of high pressure annealing (HPA) on the polarization switching process. In this paper, we have carried out a careful investigation on the switching properties of HZO capacitors annealed at 600 °C with various high pressure conditions (1, 50, and 200 atm) using the IFM model. As pressure increases to 200 atm, the ferroelectric properties were enhanced in the HZO films, and, as a result, highest remanent polarization (Pr of 24.5 μC/cm2) was observed when compared with 1 and 50 atm. Similarly, as HPA increases, the HZO capacitors showed a decrement of the coercive field, which significantly improved the switching properties. The time consumed for reversing 80% polarization was 113.1, 105.7, and 66.5 ns for the sample annealed at 1, 50, and 200 atm, respectively. From the IFM model, the smallest active field (2.997 MV/cm) and a uniform distribution of the local electric field (0.304) were observed at 200 atm. Furthermore, the characteristic time constant (τ 0) showed a decreasing trend (34.7, 18.1, and 11.7 ps) with increasing HPA. The improved switching properties and detailed findings recorded in this study may be helpful for developing the ferroelectric hafnia based non-volatile memory applications. [ABSTRACT FROM AUTHOR]

A lead-free brownmillerite ferroelectric material LiBiFe2O5 (LBFO) has been synthesized via a solid-state reaction technique. Using the procedure of N-TREOR method of X-ray diffraction, the crystal structure of the prepared sample is found to be monoclinic with lattice parameters: a = 13.6726 Å, b = 4.1560 Å, c = 8.5317 Å, and β = 102.89˚. Based on analysis of electrical data, the existence of Koop's and Maxwell–Wagner relaxation phenomena and dielectric relaxation in the material has been confirmed. This analysis has also shown a high impact of the dielectric permittivity (ϵr) and low tangent loss (tanδ) on using the material in some electronic devices. A detailed study of the frequency-temperature-dependent ac conductivity has suggested the presence of Jonscher's universal power law in the material. As the material has thermistor constant (β) values of 4019.26, 11535.75, and 484.36 in different temperature ranges indicating high-temperature NTC thermistor application. [ABSTRACT FROM AUTHOR]

HfO2-based ferroelectrics are one of the most actively developed functional materials for memory devices. However, in HfO2-based ferroelectric devices, dielectric breakdown is a main failure mechanism during repeated polarization switching. Elucidation of the breakdown process may broaden the scope of applications for the ferroelectric HfO2. Here, we report direct observations of a breakdown process in HfO2-based ferroelectric capacitors, by in situ laser-based photoemission electron microscopy. We have not only clearly visualized the hard dielectric breakdown (HDB) spot but also observed the regions responsible for the soft dielectric breakdown (SDB), which is a precursor phenomenon to HDB. It was found that the low-resistance region formed after SDB is wider than the conduction path formed after HDB. Furthermore, our spectromicroscopic analysis revealed that the photoelectron spectrum after SDB shows an enhancement in intensity without spectral-shape modulation, interpreted that the initially existed defects are increased. In the HDB spot, however, an additional shoulder structure was observed. These results provide spectroscopic evidence that the electronic states responsible for the conduction path after SDB are different from those after HDB. Through this work, we propose this microscopic approach as a versatile tool for studying buried materials as they are, accelerating the development of material engineering for advanced electronic devices. [ABSTRACT FROM AUTHOR]

The discovery of van der Waals ferroelectric materials with narrow bandgaps has opened up opportunities for the extensive adoption of self-powered ferroelectric devices that rely on the bulk photovoltaic effect. However, it still needs to overcome the challenges related to the weak ferroelectric polarization and bulk photovoltaic effect in ultrathin van der Waals ferroelectric materials. In this report, we present a synergistic effect of interface engineering and bulk photovoltaic effect in the Ta2NiS5/α-In2Se3/WSe2 van der Waals heterojunction for photodetection. The heterojunction can detect the light with a wide range of wavelengths from near-ultraviolet to near-infrared without requiring external power sources. The output current density of the self-powered heterojunction shows a linear relationship with the optical power intensity at a specific wavelength. Moreover, it accurately identifies the wavelength of light at the same optical power intensity. The on/off ratio is 1.1 × 104, 3.9 × 104, 1 × 104, and 17, respectively, when the optical power density is 100 mW/cm2 for 405, 660, 808, and 1064 nm light. The self-powered Ta2NiS5/α-In2Se3/WSe2 van der Waals photodetector exhibits high specific detectivity of 1.56 × 1011, 1.79 × 1012, 9.16 × 1010, and 1.26 × 105 Jones for wavelengths of 405, 660, 808, and 1064 nm, respectively. These results validate our strategy for enhancing the detection performance in self-powered ferroelectric van der Waals photodetectors, thus opening up possibilities for future self-powered photodetection technologies. [ABSTRACT FROM AUTHOR]

Single LiNbO3 (LNO) crystals are widely utilized in surface acoustic wave devices, optoelectronic devices, and novel ferroelectric memory devices due to their remarkable electro-optic and piezoelectric properties, and high saturation and remnant polarizations. However, challenges remain regarding their nanofabrication that hinder their applications. The prevailing etching techniques for LNO encompass dry etching, wet etching, and focused-ion-beam etching, each having distinct merits and demerits. Achieving higher etching rates and improved sidewall angles presents a challenge in LNO nanofabrication. Building upon the current etching researches, this study explores various etching methods using instruments capable of generating diverse plasma densities, such as dry etching in reactive ion etching (RIE) and inductively coupled plasma (ICP), proton exchange-enhanced etching, and wet chemical etching following high-temperature reduction treatment, as well as hybrid dry and wet etching. Ultimately, after employing RIE dry etching combined with wet etching, following a high-temperature reduction treatment, an etching rate of 10 nm/min and pretty 90° sidewall angles were achieved. Furthermore, high etching rates of 79 nm/min with steep sidewall angles of 83° were obtained using ICP dry etching. Additionally, using SiO2 masks, a high etching rate of 108 nm/min and an etching selectivity ratio of 0.86:1 were achieved. Distinct etching conditions yielded diverse yet exceptional results, providing multiple processing paths of etching for the versatile application of LNO. [ABSTRACT FROM AUTHOR]

Ferroelectricity has a wide range of applications in functional electronics, and it is extremely important for the development of the next generation of information-storage technologies. However, it is difficult to achieve in practice due to its special symmetry requirements. In this Letter, based on van der Waals stacking, a generic model is proposed for realizing ferroelectric devices in which a freely movable center layer is packaged in two fixed and symmetrically stacked layers. In this model, a ferroelectric phase transition can be realized between two equivalent and eccentric ground stacking states with opposite polarizations. By means of first-principles calculations, taking stacked hexagonal boron nitride (h-BN/h-BN/h-BN) and h-BN/graphene/h-BN as feasible models, we carefully evaluated the magnitude of ferroelectricity. The corresponding polarizations were estimated as 1.83 and 1.35 pC/m, values that are comparable to those observed in sliding ferroelectricity. Devices using this tri-layer model of vertical ferroelectricity can be constructed using arbitrary van der Waals semiconducting materials, and these will usually have low switching barriers. It is highly likely that optimized material combinations with remarkable polarization will be discovered from the huge candidate set this provides for future information-storage applications. [ABSTRACT FROM AUTHOR]

Changes in the coercive field of ferroelectric materials translate into variations in the operating power consumption of ferroelectric devices. Here, we have used partial ion substitution to reduce the coercive field in BiFeO 3 films deposited by the pulsed laser technique. We have also used mechanical loads without interruption during switching events at the nanoscale to follow the changes in the coercive field. Furthermore, we have analyzed the dependence of the coercive field concerning the injected charges during the writing process. The partial ion substitution of Ba, Ta, and Cr in the BiFeO 3 structure causes a reduction of ∼50% in the coercive field due to a weakening in the A sites -O bonds. The mechanical load experiments show that linearly increasing mechanical loading from ∼50 nN to ∼600 nN tends to increase the signal amplitude of the piezoresponse and move the coercive field locations. The linear unloading reduces the amplitude and returns the coercive field to values close to before the force experiment, pointing out a reversible process. Such behavior can be explained by considering that the piezoelectric response is supported and enhanced by the electric field created by the flexoelectric effect during the mechanical loading process due to the small tip radius. Finally, the application of negative (positive) voltage during the writing process caused the loops to shift to the left (right), changing the locations of the coercive field. [Display omitted] [ABSTRACT FROM AUTHOR]

Hafnium-based ferroelectric memories are a promising approach to enhancing integrated circuit performance, offering advantages such as miniaturization, compatibility with CMOS technology, fast read and write speeds, non-volatility, and low power consumption. However, FeRAM (Ferroelectric Random Access Memory) still faces challenges related to endurance and retention susceptibility to process variations. Hence, testing and obtaining the core parameters of ferroelectric capacitors continuously is essential to investigate these phenomena and explore the potential solution. The traditional method for measuring ferroelectric capacitors has limitations in timing generation capability, introduces parasitic capacitance, and lacks accuracy for small-area capacitors. In this study, we analyzed the working principle of ferroelectric capacitors and designed a method to detect the remnant polarization, saturation polarization, and imprint offset of ferroelectric capacitors. Further, we further proposed a circuit implementation method. The proposed test circuit conquers these limitations and enables high-precision testing of ferroelectric capacitors, contributing to developing hafnium-based ferroelectric memories. The circuit includes a flip-readout circuit, a capacitance calibration circuit, and a voltage-to-time converter and time-to-digital converter (VTC&TDC) readout circuit. According to simulation results, the capacitance calibration circuit reduces the deviation of the capacitance by 84%, and the accuracy of the readout circuit is 5.91 bits, with a readout time of 150 ns and a power consumption of 1 mW. This circuit enables low-cost acquisition of array-level small-area ferroelectric capacitance data, which can guide subsequent device optimization and circuit design. [ABSTRACT FROM AUTHOR]

Hafnium zirconium oxide (HZO) is an ideal candidate for the implementation of ferroelectric memristive devices, due to its compatibility with the complementary metal‐oxide‐semiconductor technology. Ferroelectricity in HZO films is significantly influenced by the properties of electrode/HZO interfaces. Here, the impact of the interfacial microstructure and chemistry on the ferroelectricity of 6 nm‐thick HZO‐based capacitors, realized by sputtering, with titanium nitride or tungsten electrode materials, is investigated. The results highlight a strong correlation between the structural properties of electrode/HZO interfaces and the HZO ferroelectric performance. Interface effects become significant at low HZO thickness, thus the precise control over the quality of electrode/HZO interfaces allows the remarkable improvement of HZO ferroelectric properties. A double remanent polarization of 40 µC cm−2 is achieved. This work is a new step towards high quality ultra‐thin HZO films with enhanced ferroelectricity for the implementation of ferroelectric tunnel junctions for brain‐inspired computing. [ABSTRACT FROM AUTHOR]

This study presents an investigation into the stress effect on the leakage current in ferroelectric Al 0.7 Sc 0.3 N films by experiments and density functional theory (DFT) computations. The experiments are based on 8-in. 100 nm Al 0.7 Sc 0.3 N films obtained from pulsed DC co-sputter deposition technology, which exhibit non-uniform compressive in-plane stress across the wafers and similar distributions of leakage current, suggesting close dependence between each other. DFT computations revealed that stress affects leakage current in two ways: the level of traps introduced by nitrogen vacancy and the formation energy of nitrogen vacancy in Al 0.7 Sc 0.3 N. By considering both factors, the leakage current of Al 0.7 Sc 0.3 N films increases with larger compressive in-plane stress, as observed in the experimental results. Additionally, the DFT calculation results indicated that the leakage current is more sensitive to compressive stress compared to the tensile, and the minimum leakage current can be obtained with neutral in-plane stress. These findings provide a guideline for stress engineering to optimize the AlScN-based ferroelectric devices. [ABSTRACT FROM AUTHOR]

We investigate the voltage control of magnetism in a van der Waals (vdW) heterostructure device consisting of two distinct vdW materials, the ferromagnetic Fe3-xGeTe2 and the ferroelectric In2Se3. It is observed that gate voltages applied to the Fe3-xGeTe2/In2Se3 heterostructure device modulate the magnetic properties of Fe3-xGeTe2 with significant decrease in coercive field for both positive and negative voltages. Raman spectroscopy on the heterostructure device shows voltage-dependent increase in the in-plane In2Se3 and Fe3-xGeTe2 lattice constants for both voltage polarities. Thus, the voltage-dependent decrease in the Fe3-xGeTe2 coercive field, regardless of the gate voltage polarity, can be attributed to the presence of in-plane tensile strain. This is supported by density functional theory calculations showing tensile-strain-induced reduction of the magnetocrystalline anisotropy, which in turn decreases the coercive field. Our results demonstrate an effective method to realize low-power voltage-controlled vdW spintronic devices utilizing the magnetoelectric effect in vdW ferromagnetic/ferroelectric heterostructures. The control of magnetism by electric field is an important goal for future development of low-power spintronics. Here, the authors demonstrate voltage control of magnetism in van der Waals ferromagnetic/ferroelectric heterostructure devices via the strain-mediated magnetoelectric effect. [ABSTRACT FROM AUTHOR]

Analog switching in ferroelectric devices promises neuromorphic computing with the highest energy efficiency if limited device scalability can be overcome. To contribute to a solution, one reports on the ferroelectric switching characteristics of sub‐5 nm thin Al0.74Sc0.26N films grown on Pt/Ti/SiO2/Si and epitaxial Pt/GaN/sapphire templates by sputter‐deposition. In this context, the study focuses on the following major achievements compared to previously available wurtzite‐type ferroelectrics: 1) Record low switching voltages down to 1 V are achieved, which is in a range that can be supplied by standard on‐chip voltage sources. 2) Compared to the previously investigated deposition of ultrathin Al1−xScxN films on epitaxial templates, a significantly larger coercive field (Ec) to breakdown field ratio is observed for Al0.74Sc0.26N films grown on silicon substrates, the technologically most relevant substrate‐type. 3) The formation of true ferroelectric domains in wurtzite‐type materials is for the first time demonstrated on the atomic scale by scanning transmission electron microscopy (STEM) investigations of a sub‐5 nm thin partially switched film. The direct observation of inversion domain boundaries (IDB) within single nm‐sized grains supports the theory of a gradual domain‐wall driven switching process in wurtzite‐type ferroelectrics. Ultimately, this should enable the analog switching necessary for mimicking neuromorphic concepts also in highly scaled devices. [ABSTRACT FROM AUTHOR]

Ultrawide bandgap ferroelectric nitride semiconductors have shown promising applications in electronic, micromechanical, and optical devices. Current studies, however, have largely been focused on single layer ferroelectric nitrides. Controlled polarization switching in artificial multilayer composite structures, such as ferroelectric/piezoelectric or ferroelectric/dielectric heterostructures, provides additional dimension for engineering their properties and improving device performance and functionality. Here, we demonstrate controlled ferroelectric switching in an AlN/ScAlN/AlN trilayer structure grown by molecular beam epitaxy. The trilayer showed large switchable polarization with reasonable endurance and retention performance. Polarity-sensitive wet etching further confirmed the controlled switching in the clamped ScAlN layer. The ability to control the polarity switching in ScAlN/AlN multilayers offers an intriguing avenue for the design and development of next-generation electronic, piezoelectronic, and ferroelectric devices. [ABSTRACT FROM AUTHOR]

Flexoelectricity has been shown to be an effective strategy to modulate the polarization configurations, domain structures, and physical properties in nanoscale ferroelectric thin films. However, the relations between the domain switching processes and flexoelectric effects remain elusive, which is essential for the design of nanoscale ferroelectric electric devices. In this work, strain-gradient and normal PbTiO3 films are fabricated and investigated to resolve this elusive relationship. By using large-scale and local piezoelectric force microscopy characterization, the ferroelectric domain switching in strain-gradient PbTiO3 films is found to be hard and hindered under applied electric fields compared with the normal ones. Successive atomic-scale scanning transmission electron microscopy imaging analysis manifests that the domains in the strain-gradient PbTiO3 films are stabilized by an additional effective strain gradient-induced flexoelectric field, which was introduced by negative pressure originated from vertically distributed Pb-rich anti-phase domains. This study proposes an effective method to stabilize the ferroelectric polarization in nanoscale ferroelectric films, thus facilitate improving the reliability of ferroelectric electronic devices. [ABSTRACT FROM AUTHOR]

We explore the coexistence region in the vicinity of the Mott critical end point employing a compressible cell spin- 1 / 2 Ising-like model. We analyze the case for the spin-liquid candidate κ -(BEDT-TTF) 2 Cu 2 (CN) 3 , where close to the Mott critical end point metallic puddles coexist with an insulating ferroelectric phase. Our results are fourfold: (i) a universal divergent-like behavior of the Grüneisen parameter upon crossing the first-order transition line; (ii) based on scaling arguments, we show that within the coexistence region, for any system close to the critical point, the relaxation-time is entropy-dependent; (iii) we propose the electric Grüneisen parameter Γ E , which quantifies the electrocaloric effect; and (iv) we identify the metallic/insulating coexistence region as an electronic Griffiths-like phase. Our findings suggest that Γ E governs the dielectric response close to the critical point and that an electronic Griffiths-like phase emerges in the coexistence region. [ABSTRACT FROM AUTHOR]

The development of electronic materials for storing electrical energy is a thriving research field, where the materials used in batteries, supercapacitors, and dielectric capacitors have attracted extensive interest in last decades. The dielectric capacitors showing unique characteristics such as high power density and large charge/discharge rate have been actively studied, where the antiferroelectrics demonstrate great potentials for dielectric energy storage applications by storing and releasing energy upon a reversible electric-field induced antiferroelectric- ferroelectric phase transition. Recently, lead-free antiferroelectric AgNbO3 has emerged as a promising candidate to substitute conventional lead-based antiferroelectrics (such as PbZrO3) in energy storage applications. The phase transition dynamics of AgNbO3 is driven by a complex sequence of oxygen octahedron tilting orders in addition to cation displacement, which can be effectively engineered by a doping strategy. In this article, we present a succinct overview of the phase transition mechanisms in AgNbO3-based ceramics and describe how the phase transition characteristics are affected by the dopants. By exploring the composition related average structure and local structural evolutions, we provide a view toward the goal of establishing a link between the phase transition and physical properties tailored for dielectric energy storage applications. The development of electronic materials for storing electrical energy is a thriving research field, where the materials used in batteries, supercapacitors, and dielectric capacitors have attracted extensive interest in last decades. The dielectric capacitors showing unique characteristics such as high power density and large charge/discharge rate have been actively studied, where the antiferroelectrics demonstrate great potentials for dielectric energy storage applications by storing and releasing energy upon a reversible electric-field induced antiferroelectric- ferroelectric phase transition. Recently, lead-free antiferroelectric AgNbO3 has emerged as a promising candidate to substitute conventional lead-based antiferroelectrics (such as PbZrO3) in energy storage applications. The phase transition dynamics of AgNbO3 is driven by a complex sequence of oxygen octahedron tilting orders in addition to cation displacement, which can be effectively engineered by a doping strategy. In this article, we present a succinct overview of the phase transition mechanisms in AgNbO3-based ceramics and describe how the phase transition characteristics are affected by the dopants. By exploring the composition related average structure and local structural evolutions, we provide a view toward the goal of establishing a link between the phase transition and physical properties tailored for dielectric energy storage applications. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT) is the promising candidate in advanced ferroelectric memory application due to its excellent piezoelectricity, ferroelectricity, pyroelectricity, non-linear dielectric behavior, multiferroic properties, high ferroelectric Curie temperature, and extremely strong stability. It has gained attention in the field beyond von-Neumann computing, which inspires the development of computation in memory applications. Various structures of the ferroelectric memristive device, including ferroelectric field effect transistor, tunnel junctions, nonvolatile memory, and capacitor, based on PZT have been proposed for the realization of computation in memory application. On the other hand, unique designs realize the performance enhancement of PZT ferroelectric memristive devices, i.e., the insertion of 2D material MXene. This perspective further points out some of the challenges that MXene-PZT based ferroelectric memristive devices encounter in reality and finally give our viewpoint on possible developments toward computation in memory in a neuromorphic platform. [ABSTRACT FROM AUTHOR]

Hafnium oxide–based ferroelectric materials are promising candidates for next-generation nanoscale devices because of their ability to integrate into silicon electronics. However, the intrinsic high coercive field of the fluorite-structure oxide ferroelectric devices leads to incompatible operating voltage and limited endurance performance. We discovered a complementary metal-oxide semiconductor (CMOS)–compatible rhombohedral ferroelectric Hf(Zr)1+xO2 material rich in hafnium-zirconium [Hf(Zr)]. X-ray diffraction combined with scanning transmission electron microscopy reveals that the excess Hf(Zr) atoms intercalate within the hollow sites. We found that the intercalated atoms expand the lattice and increase the in-plane and out-of-plane stresses, which stabilize both the rhombohedral phase (r-phase) and its ferroelectric properties. Our ferroelectric devices, which are based on the r-phase Hf(Zr)1+xO2, exhibit an ultralow coercive field (~0.65 megavolts per centimeter). Moreover, we achieved a high endurance of more than 1012 cycles at saturation polarization. This material discovery may help to realize low-cost and long-life memory chips. [ABSTRACT FROM AUTHOR]

Hf1−xZrxO2 (HZO) thin films are versatile materials suitable for advanced ferroelectric semiconductor devices. Previous studies have shown that the ferroelectricity of HZO thin films can be stabilized by doping them with group III elements at low concentrations. While doping with Y improves the ferroelectric properties, there has been limited research on Y-HZO thin films fabricated using atomic layer deposition (ALD). In this study, we investigated the effects of Y-doping cycles on the ferroelectric and electrical properties of as-deposited Y-HZO thin films with varying compositions fabricated through ALD. The Y-HZO thin films were stably crystallized without the need for post-thermal treatment and exhibited transition behavior depending on the Y-doping cycle and initial composition ratio of the HZO thin films. These Y-HZO thin films offer several advantages, including enhanced dielectric constant, leakage current density, and improved endurance. Moreover, the optimized Y-doping cycle induced a phase transformation that resulted in Y-HZO thin films with improved ferroelectric properties, exhibiting stable behavior without fatigue for up to 1010 cycles. These as-deposited Y-HZO thin films show promise for applications in semiconductor devices that require high ferroelectric properties, excellent electrical properties, and reliable performance with a low thermal budget. [ABSTRACT FROM AUTHOR]

HfAlO film‐based ferroelectric memory is a strong contender for the next‐generation nonvolatile memories. However, the remanent polarization intensity of HfAlO films is small compared to other Hf‐based ferroelectric films at low annealing temperatures. In order to further improve the remnant polarization of the device, the ferroelectric memory with metal‐ferroelectric‐metal structure using ZrO2 as the regulating layer (RL) is designed and fabricated. Experimental results show that the device with the ZrO2 regulating layer exhibits triple enhancement, which may be due to the fact that ZrO2 RL has an effect on the enhancement of the ferroelectric phase. In addition, the device with ZrO2 regulating layer exhibits a superior ON/OFF conductance ratio, endurance, and retention characteristics, demonstrating potential for application to memory. This work provides an effective way to improve the ferroelectricity in HfAlO films at low annealing temperatures. [ABSTRACT FROM AUTHOR]

The tunneling electroresistance (TER) ratio is an important device merit of ferroelectric tunnel junction (FTJ) and multiferroic tunnel junction (MFTJ) devices. Here, through first-principles calculations, we propose an efficient way to achieve a sizable TER effect through the interface engineering in both SrRuO3/PbTiO3/FeO/Fe and SrRuO3/PbTiO3/CoO/Co MFTJs. It is found that the interfacial FeO or CoO layer can significantly modify the band alignment between PbTiO3 barrier and electrodes through its large depolarization field, causing the insulating–metallic transition of PbTiO3 barrier upon polarization reversal. As a result, the tunneling resistance changes significantly, leading to a giant TER effect of 105%. Our results suggest a practical way to enhance the TER effect in MFTJs. [ABSTRACT FROM AUTHOR]