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In spite of the flexoelectric effect being a universal phenomenon in the ferroelectric perovskites, the current understanding of flexoelectric aging in ferroelectrics is, actually, rather incomplete. In this paper, we have fabricated a series of Mn-doped BaTiO3 perovskite ceramics (BaTi1–xMnxO3, x = 0.1% and 1%, BTMO) to systematically investigate the corresponding flexoelectric aging behavior by controlling the concentration of Mn. We found that the variation of Mn dopant significantly effects the Curie temperature, dielectric constant, flexoelectric aging, and flexoelectric coefficient of the BTMO ceramics. Especially for the BTMO (0.1%) ceramics, obvious ferroelectric aging and flexoelectric aging phenomenon are observed at room temperature. The main reason for aging of BTMO ceramics is that the doping of Mn introduces oxygen vacancies, which tend to be stable under the action of strain gradient and electric field. Therefore, the results presented in this paper verify that the flexoelectric aging in Mn-doped BTO ceramics is closely related to ferroelectric fatigue. [ABSTRACT FROM AUTHOR]

This paper presents the experimental evidence of reversible insulator–metal transition (IMT) in thin-film amorphous molybdenum trioxide (MoO3) induced by electric fields of just a few volts. The presence of oxygen vacancies in MoO3 is considered to play a significant role in the reported reversible IMT. The oxygen vacancies not only impact MoO3 stoichiometry but also the optical bandgap. The subthreshold slope for IMT in 10 nm-thick MoO3-based devices is 48.3 mV/decade, which represents a transition from an insulator to a metallic state, and the electric field threshold for such a transition was found to be equal to 0.034 V/Å. Following the IMT in MoO3, there are six orders of magnitude differences between the resistivity of the insulator state (27.5 M Ω at −9 V) and the metallic state (80 Ω between +5 and +9 V). In addition, we reported stabilization of a nanocrystalline hexagonal MoO3 (h-MoO3) phase in thicker MoO3 (150 nm-thick) in the presence of oxygen vacancies that behave as a wide bandgap (3.1 eV) ferroelectric semiconductor with a coercive field of about 50 kV/cm, a saturation polarization of about 30 μC/cm2, and a remanent polarization of about 10 μC/cm2. This ferroelectricity in nanocrystalline h-MoO3 (150 nm-thick) remains stable even after 8 months of storage of the sample in ambient conditions, with remanent polarization increasing up to 20 μC/cm2. These are unexpected results from MoO3. [ABSTRACT FROM AUTHOR]

In this paper, the field-induced residual ferroelectricity in antiferroelectric lead zirconate thin films has been studied by impedance measurements together with a hyperbolic law analysis, which permits us to extract the different contributions to the material's complex permittivity. By measuring the Rayleigh coefficient α r , it appears that the residual ferroelectricity is considerably enhanced when the sample has been previously exposed to an electric field close to the antiferroelectric to ferroelectric transition field. This indicates that a part of the material remains ferroelectric after the antiferroelectric–ferroelectric backward transition, which constitutes an additional contribution to polarization. Consequently, a higher domain wall density and mobility can be observed. Measurements after exposition to thermal treatment show that this ferroelectric response is metastable. [ABSTRACT FROM AUTHOR]

Ferroelectric HfO2 has attracted much attention owing to its superior ferroelectricity at an ultra-thin thickness and good compatibility with Si-based complementary metal–oxide–semiconductor (CMOS) technology. However, the crystallization of polar orthorhombic phase (o-phase) HfO2 is less competitive, which greatly limits the ferroelectricity of the as-obtained ferroelectric HfO2 thin films. Fortunately, the crystallization of o-phase HfO2 can be thermodynamically modulated via interfacial stress engineering. In this paper, the growth of improved ferroelectric Al doped HfO2 (HfO2:Al) thin films on (111)-oriented Si substrate has been reported. Structural analysis has suggested that nonpolar monoclinic HfO2:Al grown on (111)-oriented Si substrate suffered from a strong compressive strain, which promoted the crystallization of (111)-oriented o-phase HfO2 in the as-grown HfO2:Al thin films. In addition, the in-plane lattice of (111)-oriented Si substrate matches well with that of (111)-oriented o-phase HfO2, which further thermally stabilizes the o-phase HfO2. Accordingly, an improved ferroelectricity with a remnant polarization (2 P r) of 26.7 μC/cm2 has been obtained. The results shown in this work provide a simple way toward the preparation of improved ferroelectric HfO2 thin films. [ABSTRACT FROM AUTHOR]

Viscosity, elasticity, and viscoelastic properties are one of the most fundamental properties of liquid crystalline materials; the main problem in determining these properties is the multitude of physical parameters needed to determine the values of elasticity and viscosity constants. In this paper, a number of different measurement methods for the complete characterization of viscoelastic properties for smectic liquid crystalline materials and their mixtures are analyzed, both theoretically and experimentally. The way in which viscoelastic material constants are determined depends mainly on the application/purpose of the materials under study. The subject of this work was to review the methods used to determine viscoelastic effects in ferroelectric and antiferroelectric chiral liquid crystals, their mixtures, composite materials, and even in dielectric systems, which would bear the hallmark of a universal method allowing the application of sufficiently low electric fields. In the case of chiral liquid crystals with ferroelectric and antiferroelectric phases and their subphases, the following assumption applies: fulfilment of Hooke's law (in the case of elastic coefficients) and preservation of laminar flow (in the case of viscosity coefficients). [ABSTRACT FROM AUTHOR]

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The ever-increasing demand for high-speed data transmission in telecommunications and data centers has driven the development of advanced on-chip integrated electro-optic modulators. Silicon modulators, constrained by the relatively weak carrier dispersion effect, face challenges in meeting the stringent requirements of next-generation photonic integrated circuits. Consequently, there has been a growing interest in Pockels effect-based electro-optic modulators, leveraging ferroelectric materials like LiNbO3, BaTiO3, PZT, and LaTiO3. Attributed to the large first-order electro-optic coefficient, researchers have delved into developing modulators with expansive bandwidth, low power consumption, compact size, and linear response. This paper reviews the working principles, fabrication techniques, integration schemes, and recent highlights in Pockels effect-based modulators. [ABSTRACT FROM AUTHOR]

Ferroelectric photovoltaic (PV) materials have garnered considerable interest because of their distinctive switchable PV characteristics. Nevertheless, their ability to function within a wide range of ambient temperatures was previously constrained. This paper describes the construction of ferroelectric capacitors featuring an Au/PZT (Pb(Zr 0. 40 Ti 0.60)O 3)/FTO (SnO 2 :F) heterojunction through the utilization of the sol-gel technique. The performance analysis findings indicate that the PZT material, following optimization of annealing temperature, displayed strong ferroelectric properties and notable frequency-dependent dielectric behavior. An increase in temperature (25°C∼300°C) revealed that short-circuit current density J sc exhibited an upward → downward → upward trend and reached 399.6 μA/cm2 at 300°C. Energy band analysis showed the presence of spontaneous polarization and a large work function difference between the bottom electrode FTO and the top electrode Au (∼0.42 eV) created a strong built-in electric field in the PZT films, which was conducive to the photogenerated carriers' separation and greatly improved the PZT film ferroelectric PV. In this paper, transparent ferroelectric materials were demonstrated for the first time to exhibit a photoelectric responsivity of up to 1.77 mA/W at a temperature of 300°C, offering a practical strategy for the implementation of transparent ferroelectric photovoltaic devices in high-temperature environments, particularly those subjected to intense solar energy harvesting and conversion. [ABSTRACT FROM AUTHOR]

This paper investigates In 0. 7 Ga 0. 3 As/Ga 0. 5 As 0. 5 Sb-based Heterojunction Tunnel Field Effect Transistor with ferroelectric dielectric as stack layer, namely Ferroelectric Dual Material Stacked Double Gate Heterojunction TFET (FDMSDG-HJTFET) for the first time for performance and reliability. Ferroelectric gate dielectric has been inculcated in the device design in addition to the doping of Ga 0. 5 As 0. 5 Sb in the source region and In 0. 7 Ga 0. 3 As in the drain region, respectively. The performance of the proposed device is quantified in terms of DC electrical parameters and short channel parameters. The reliability analysis of the proposed device has been carried out in terms of influence of variations of interface trap charges, gate-source overlap length and temperature on the device transfer characteristics. From the simulation results, it can be manifested that the proposed device presents superior DC electrical characteristic and reduced short channel effects as compared to the GaSb/Si Dual Material Stacked Double Gate Heterojunction TFET (GaSb/Si DMSDG-HJTFET), under the influence of group III–V materials and ferroelectric gate dielectric. In addition to this, the proposed device depicts elevated immunity to presence of interface trap charges at the interface, variations in gate-source overlap length and temperature variations as well. The implication of TiO2 as dielectric stack over SiO2 provides exceptional capacitive coupling at the interface and thus assists in the improvement of electrical characteristics of the device by enhancing the electric field. The outcome of the simulation results presents that Ga 0. 5 As 0. 5 Sb/In 0. 7 Ga 0. 3 As-based Ferroelectric Dual Material Stacked Double Gate Heterojunction TFET (FDMSDG-HJTFET) can prove to be a competitive alternative for high performance applications with improved reliability. The design and simulation of the proposed device structure has been executed using technology computer-aided design (TCAD) tool. [ABSTRACT FROM AUTHOR]

Monoclinic ferroelectric phases are prevalent in various functional materials, most notably mixed‐ion perovskite oxides. These phases can manifest as regularly ordered long‐range crystallographic structures or as macroscopic averages of the self‐assembled tetragonal/rhombohedral nanodomains. The structural and physical properties of monoclinic ferroelectric phases play a pivotal role when exploring the interplay between ferroelectricity, ferroelasticity, giant piezoelectricity and multiferroicity in crystals, ceramics and epitaxial thin films. However, the complex nature of this subject presents challenges, particularly in deciphering the microstructures of monoclinic domains. In Paper I [Biran & Gorfman (2024). Acta Cryst. A80, 112–128] the geometrical principles governing the connection of domain microstructures formed by pairing MAB type monoclinic domains were elucidated. Specifically, a catalog was established of 'permissible domain walls', where 'permissible', as originally introduced by Fousek & Janovec [J. Appl. Phys. (1969), 40, 135–142], denotes a mismatch‐free connection between two monoclinic domains along the corresponding domain wall. The present article continues the prior work by elaborating on the formalisms of permissible domain walls to describe domain microstructures formed by pairing the MC type monoclinic domains. Similarly to Paper I, 84 permissible domain walls are presented for MC type domains. Each permissible domain wall is characterized by Miller indices, the transformation matrix between the crystallographic basis vectors of the domains and, crucially, the expected separation of Bragg peaks diffracted from the matched pair of domains. All these parameters are provided in an analytical form for easy and intuitive interpretation of the results. Additionally, 2D illustrations are provided for selected instances of permissible domain walls. The findings can prove valuable for various domain‐related calculations, investigations involving X‐ray diffraction for domain analysis and the description of domain‐related physical properties. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to study the intrinsic mechanical contributions of poled piezoelectric ceramics under the three ferroelectric phases [tetragonal (4 mm), rhombohedral (3 m) and orthorhombic (mm2)]. The intrinsic elastic coefficients and spontaneous strains of saturated and unsaturated poling piezoelectric ceramics are analyzed and calculated by probability density functions of orientation (PDFOs) and Reuss or Voigt average, and the analytical results of the intrinsic mechanical properties of piezoelectric ceramics with the poling degree are obtained. In addition, this paper also calculates the Young's modulus and shear modulus of barium titanate (BaTiO3) piezoelectric ceramics by PDFO which are based on the Reuss, Voigt and Hill averages. Comparing them with the published theoretical calculation data shows that the results calculated by the finite element method under the saturated and unsaturated poling states are within the range of the results calculated by us using the three average theories through PDFO, and it shows the accuracy of calculation by PDFO. [ABSTRACT FROM AUTHOR]

Ferroelectricity in biological system has been anticipated both theoretically and experimentally over the past few decades. Claims of ferroelectricity in biological systems have given rise to confusion and methodological controversy. Over the years, a "loop" of induced polarization in response to a varying applied electrical field and a consequent polarization reversal has prompted many researchers to claim ferroelectricity in biological structures and their building blocks. Other observers were skeptical about the methodology adopted in generating the data and questioned the validity of the claimed ferroelectricity as such, "loop" can also be obtained from linear capacitors. In a paper with somewhat tongue-in-cheek title, Jim Scott showed that ordinary banana peels could exhibit closed loops of electrical charge which closely resemble and thus could be misinterpreted as ferroelectric hysteresis loops in barium sodium niobate, BNN paraphrasing it as "banana". In this paper, we critically review ferroelectricity in biological system and argue that knowing the molecular and crystalline structure of biological building blocks and experimenting on such building blocks may be the way forward in revealing the "true" nature of ferroelectricity in biological systems. [ABSTRACT FROM AUTHOR]

Ferroelectricity in hafnium zirconium oxide (Hf1 − xZrxO2) and the factors that impact it have been a popular research topic since its discovery in 2011. Although the general trends are known, the interactions between fabrication parameters and their effect on the ferroelectricity of Hf1 − xZrxO2 require further investigation. In this paper, we present a statistical study and a model that relates Zr concentration (x), film thickness (tf), and annealing temperature (Ta) with the remanent polarization (Pr) in tungsten (W)-capped Hf1 − xZrxO2. This work involved the fabrication and characterization of 36 samples containing multiple sets of metal-ferroelectric-metal capacitors while varying x (0.26, 0.48, and 0.57), tf (10 and 19 nm), and Ta (300, 400, 500, and 600 ° C). In addition to the well-understood effects of x and Ta on the ferroelectricity of Hf1 − xZrxO2, the statistical analysis showed that thicker Hf1 − xZrxO2 films or films with higher x require lower Ta to crystallize and demonstrated that there is no statistical difference between samples annealed to 500 and 600 ° C, thus suggesting that most films fully crystallize with Ta ∼ 500 ° C for 60 s. Our model explains 95% of the variability in the Pr data for the films fabricated, presents the estimates of the phase composition of the film, and provides a starting point for selecting fabrication parameters when a specific Pr is desired. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) valleytronic materials are both fundamentally intriguing and practically appealing to explore novel physics and design next-generation devices. However, traditional control means such as optic pumping or magnetic field cannot meet the demands of modern electron devices for miniaturization, low-dissipation, and non-volatility. Thus, it is attractive to combine the ferroelectric property with valley property in a single compound. In this paper, the recent progress of ferroelectric-valley coupling is reviewed. First, we briefly recall the development of valleytronics in the past several years. Then, various structures demonstrating ferroelectric-valley coupling, including heterostructures and intrinsic materials, are introduced. Subsequently, we describe ferroelectric-valley coupling in sliding and adsorption system and the unconventional ferroelectricity in the moiré system. Finally, we discuss the research status and outlook. We hope that this perspective will be helpful to bridge the gap between valleytronics and ferroelectrics in 2D materials and inspire further exciting findings. [ABSTRACT FROM AUTHOR]

This paper reports the onset of ferroelectricity in NiO by breaking the crystallographic symmetry with oxygen vacancies created by N doping. Nitrogen-doped NiO was grown at room temperature by RF sputtering of Ni target in Ar–O2–N2 plasma on silicon and fused silica substrates. The impact of the nitrogen doping of NiO on microstructural, optical, and electrical properties has been investigated. According to x-ray diffraction investigations, by increasing the N doping level in NiO, a transition from (002) to a (111) preferential orientation for the cubic NiO phase was observed, as well as a lattice strain relaxation, that is usually ascribed to structural defect formation in crystal. The x-ray diffraction pole figures the presence of a distorted cubic structure in NiO and supports the Rietveld refinement findings related to the strain, which pointed out that nitrogen doping fosters lattice imperfections formation. These findings were found to be in agreement with our far-infrared measurements that revealed that upon nitrogen doping a structural distortion of the NiO cubic phase appears. X-ray photoemission spectroscopy measurements reveal the presence of oxygen vacancies in the NiO film following nitrogen doping. Evidence of ferroelectricity in nitrogen-doped NiO thin films has been provided by using the well-established Sawyer–Tower method. The results reported here provide the first insights on oxygen-vacancy induced ferroelectricity in nitrogen-doped nickel oxide thin films. [ABSTRACT FROM AUTHOR]

Ferroelectricity and magnetism seldom coexist due to mutual exclusiveness. Recent attempts have been made to achieve the coexistence of ferroelectricity and magnetism in polar magnets. In this paper, we investigated the magnetic properties, dielectric relaxation, and magnetodielectric (MD) effect of polar Dy2Cu2O5 ceramic. At the antiferromagnetic ordering temperature, the dielectric constant (ɛ) curves exhibit a spontaneous change in slope, indicating strongly coupled charge and spin degrees of freedom. With increase in the magnetic field intensity, the simultaneous suppression of the dielectric anomaly and the antiferromagnetic transformation demonstrates the existence of the MD effect. It is important to note that ɛ varies nonmonotonically with the magnetic field. Below the magnetic ordering temperature, ɛ increases continuously before the metamagnetic transition and then decreases after that. The results are discussed in terms of the magnetic field-induced change of spin configuration and spin–phonon coupling. Moreover, two dielectric relaxation-related steps are observed, which are correlated with the electrons hopping within and among the zigzag chains of Cu2+, respectively. This work helps understand the dielectric behavior and the MD effect in materials with complicated spin structures. [ABSTRACT FROM AUTHOR]

This review reports the latest trends in the ceramic composite matrix used for the magnetoelectric (ME) effect. In the last few years, ME composite has become the center of attraction for use in various electrically and magnetically coupled devices. The growth and use of electronic components everywhere have propulsively accelerated the exploration of self-powered electronic and sensor network devices. ME is a feasible technique for addressing difficulties of traditional batteries such as short life span and frequent recharge difficulties. Self-charging multiferroic components have been found for the constant working of mobile electronics that use multiferroic composites in response to magnetoelectric energy transformation. Researchers have rigorously studied the rigid and flexible magnetoelectric composites for their suitability in applications. This paper gives a comparative study between rigid and flexible magnetoelectric composites based on their properties and provides knowledge about the materials for such types of composites. It reviews the latest polymer-based ME materials as well as the related fabrication and polarization methods. The review finally encapsulates the applications in biomedicine, ranging from mechanical energy harvesters to sensors and actuators. [ABSTRACT FROM AUTHOR]

Pyroelectric materials are naturally electrically polarized and exhibits a built-in spontaneous polarization in their unit cell structure even in the absence of any externally applied electric field. These materials are regarded as one of the ideal detector elements for infrared applications because they have a fast response time and uniform sensitivity at room temperature across all wavelengths. Crystals of the perovskite lead titanate (PbTi O 3 ) family show pyroelectric characteristics and undergo structural phase transitions. They have a high Curie temperature (the temperature at which the material changes from the ferroelectric (polar) to the paraelectric (nonpolar) phase), high pyroelectric coefficient, high spontaneous polarization, low dielectric constant, and constitute important component materials not only useful for infrared detection, but also with vast applications in electronic, optic, and MEMS devices. However, the preparation of large perfect and pure single crystals PbTi O 3 is challenging. Additionally, difficulties arise in the application of such bulk crystals in terms of connection to processing circuits, large size, and high voltages required for their operation. In this part of the review paper, we explain the electrical behavior and characterization techniques commonly utilized to unravel the pyroelectric properties of lead titanate and its derivatives. Further, it explains how the material preparation techniques affect the electrical characteristics of resulting thin films. It also provides an in-depth discussion of the measurement of pyroelectric coefficients using different techniques. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) materials are considered attractive semiconducting layers for emerging field-effect transistors owing to their unique electronic and optoelectronic properties. Polymers have been utilized in combination with 2D semiconductors as gate dielectric layers in field-effect transistors (FETs). Despite their distinctive advantages, the applicability of polymer gate dielectric materials for 2D semiconductor FETs has rarely been discussed in a comprehensive manner. Therefore, this paper reviews recent progress relating to 2D semiconductor FETs based on a wide range of polymeric gate dielectric materials, including (1) solution-based polymer dielectrics, (2) vacuum-deposited polymer dielectrics, (3) ferroelectric polymers, and (4) ion gels. Exploiting appropriate materials and corresponding processes, polymer gate dielectrics have enhanced the performance of 2D semiconductor FETs and enabled the development of versatile device structures in energy-efficient ways. Furthermore, FET-based functional electronic devices, such as flash memory devices, photodetectors, ferroelectric memory devices, and flexible electronics, are highlighted in this review. This paper also outlines challenges and opportunities in order to help develop high-performance FETs based on 2D semiconductors and polymer gate dielectrics and realize their practical applications. [ABSTRACT FROM AUTHOR]

DaltonTransactions An international journal of inorganic chemistry rsc. li/ dalton Volume 53 Number 45 7 December 2024 Pages 18057- 18386 ISSN 1477- 9226 PAPER Minoru Osada et al. Ferroelectricity in CsPb 2 Nb 3 O 10 and exfoliated 2D nanosheets [Extracted from the article]

Pb-based perovskites play pivotal roles in ferroelectric research. In the search for new Pb-based ferroelectrics, we investigated the ferroelectric properties of Dion–Jacobson type CsPb2Nb3O10 and exfoliated 2D nanosheets. Ferroelectricity in CsPb2Nb3O10 was demonstrated for the first time. CsPb2Nb3O10 adopted a polar tetragonal structure with a modest TC = 260 °C and polarization PS = 7.93 μC cm−2; the polarization mainly arose from the out-of-plane displacements of Nb5+ ions and nearby oxygens. CsPb2Nb3O10 layered perovskite offers additional advantages for tailoring ferroelectric nanomaterials, as exfoliated 2D nanosheets provide novel platforms for investigating ferroelectric properties down to the 2D limit. Piezoresponse force microscopy confirmed stable ferroelectricity even in exfoliated 2D Pb2Nb3O10 nanosheets. [ABSTRACT FROM AUTHOR]

In this paper, the calcium-doped nickel-zinc nano-ferrites [Ni 0.5 Zn 0.5 Ca x Fe 2-x O 4 ; x = 0.00, 0.10, and 0.30] were prepared using the chemical co-precipitation synthesis route and studied for switching field high-frequency device applications. The structural analysis has been completed by analyzing X-ray diffraction (XRD) patterns. The Rietveld refined XRD patterns confirmed the formation of cubic spinel structure of Ca2+ substituted nickel-zinc ferrites. The detection of metal-oxygen bonds present at A and B lattice sites has been unveiled by Fourier transform infrared (FTIR) spectroscopy. The morphological studies obtained through FESEM (Field emission scanning electron microscopy) analysis showed a reduction in the particle size from 70 nm to 53 nm when the concentration of Ca2+ ions in Ni-Zn ferrites was increased. Energy dispersive spectra (EDS) confirmed the presence of elements present in the prepared composition. The structure of a cubic spinel-shaped unit cell has been verified from three active prominent Raman modes (A 1g , A 2g , and T 2g). Diffuse-reflectance spectroscopy (DRS) exhibits the increment in the bandgap values (from 1.55 eV to 1.63 eV) which helps fabricate highly efficient photovoltaic devices. The ferroelectric measurements yielded a rise in polarization values from 1.461 μC/cm2 to 18.228 μC/cm2 for 10 % Ca2+ ion substitution. The tangent loss values declined from 24 to 3 in Ni-Zn ferrites upon substituting Ca2+ ions. The Vibrating sample Magnetometer (VSM) technique found the increment in the saturation magnetization (M s) values from 34.724 emu/g to 54.662 emu/g on substituting up to 30 % Ca2+ ions in Ni-Zn ferrites. These obtained results support the material in switching field distribution for high-frequency applications. The results exhibited that the prepared samples can be applicable for switching devices, filters, and microwave absorption devices. The results revealed the maximum frequency between 12 and 18 GHz which is useful for Ku band absorption. [ABSTRACT FROM AUTHOR]

This paper presents data on the macroscopic polarization of copolymer films of vinylidene fluoride with tetrafluoroethylene obtained with a modified apparatus assembled according to the Sawyer–Tower Circuit. The kinetics of the polarization process were analyzed taking into consideration the contributions of both bound and quasi-free (impurity) charges. It was shown that an "abnormal" decrease in conductivity was observed in fields near the coercive fields. This could be associated with the appearance of deep traps of the impurity charge carriers formed by the polar planes of β-phase crystals. The conductivity data obtained from the charge and current responses differed. It was concluded that chain segments contributing to polarization with sufficiently low fields were present in the amorphous phase. A comparison showed that the average size of β-phase crystals (crystals of X-ray diffraction reflection width) was almost one order of magnitude lower than the domain size obtained using piezoresponse force microscopy (PFM). The analysis of the fast-stage dielectric response before and after polarization indicated that as the external polarizing field increased in the ferroelectric polymer chains, conformational transitions occurred according to the T3GT3G− → (-TT-)n и TGTG → (-TT-)n types. This was accompanied by an increase in the effective dipole moment in the amorphous phase chains. The analysis of the IR spectroscopy data obtained in transmission and ATR modes revealed a difference in the conformational states of the chains in the core and surface parts of the film. [ABSTRACT FROM AUTHOR]

Recently, two-dimensional (2D) bilayer magnetic systems have been widely studied. Their interlayer magnetic interactions play a vital role in the magnetic properties. In this paper, we theoretically studied the interlayer magnetic interactions, magnetic states, and ferroelectricity of π / 3 -twisted CrX2 (X = Se, Te) bilayers (π / 3 -CrX2). Our study reveals that the lateral shift could switch the magnetic state of the π / 3 -CrSe2 between interlayer ferromagnetic and antiferromagnetic, while just tuning the strength of the interlayer antiferromagnetic interactions in π / 3 -CrTe2. Furthermore, the lateral shift can alter the off-plane electric polarization in both π / 3 -CrSe2 and π / 3 -CrTe2. These results show that stacking is an effective way to tune both the magnetic and ferroelectric properties of 1T-CrX2 bilayers, making the 1T-CrX2 bilayers hold promise for 2D spintronic devices. [ABSTRACT FROM AUTHOR]

The metastable polar orthorhombic phase is believed to be the origin of the ferroelectricity of hafnia-based films. The adjustment of stain, oxygen vacancies and dopant during film deposition and the wake-up electric cycling are common strategies to induce the ferroelectricity in hafnia. However, none of them could independently render the ferroelectric phase to be the most stable phase from the theoretical calculation results. The exact external conditions to stabilize orthorhombic phase still remain elusive. In this paper, we investigate the effects of the type, distribution, concentration, and charge state characteristics of oxygen vacancies and the uniaxial strain on the crystal' energy, dielectric constant and spontaneous polarization (Ps); In addition, the impact of the applied electric field parallel to the Ps on the crystal' energy is explored by first-principles calculations. It is challenging to independently stabilize the ferroelectric phase of hafnia-based films by a single component owing to the rather strict conditions. Surprisingly, the ferroelectricity can be easily obtained when simultaneously considering the effects of oxygen vacancies, uniaxial strain, and applied electric fields, suggesting the extremely important mechanical-electrical-chemical coupling effects. This work provides an explanation for the typical wake-up phenomenon in hafnia and a guidance for film applications. [ABSTRACT FROM AUTHOR]

This paper is devoted to a comprehensive study on a new type of microwave structures named magnetoelectric (ME) gradient structures. These structures are studied in this paper to understand the possibilities and application principles in feasible devices. The structure under study was calculated at different values of the applied electric field and different values of the relative permittivity of the artificial dielectric layer. The layered multiferroic structure in inhomogeneous electric and magnetic fields was calculated on the basis of the previously proposed mathematical model. The eigenwaves spectrum for several considered cases was the result of the performed calculation. The concept of using ME gradient structures in the design of electronically controlled microwave devices is formed on the basis of the results of a numerical experiment. Structures of this type will preferably be used in electronically controlled devices for the directional transmission of microwave signals, as it was shown in the theoretical part of the paper. [ABSTRACT FROM AUTHOR]

Ferroelectric field effect transistors (FeFETs), characterized by their low power consumption and polarization effect, can be employed in photodetectors based on 2D materials. In this paper, a MoS2 phototransistor with epitaxial ferroelectric (Hf0.5Zr0.5)O2 (HZO) is reported as a gate dielectric layer. Gate‐dielectric‐polarization‐dependent ambipolar behavior is observed in the FET, and relatively low power consumption and hysteresis‐free loop are achieved in the FeFET. The anomalous negative photoconductivity (NPC) is observed as well. Possible reasons for such phenomenon are clarified including the photogating effect originating from the interface traps and the polarization‐dependent electric‐field control through ferroelectric gating. The high responsivity of −8.44 × 103 A W−1 in the negative photoconductivity as well as the response time of 500 ms are reported. The demonstrated Molybdenum disulfide (MoS2) FeFET photodetectors show great potential in the on‐chip complementary metal‐oxide semiconductor (CMOS)‐compatible circuits for multifunctional devices. [ABSTRACT FROM AUTHOR]

The atmospheric chemical vapor deposition (APCVD) method has been widely applied to synthesize high-quality two-dimensional materials. GeTe has many intriguing properties, such as phase transition, thermoelectric and ferroelectricity, which allow unique opportunities for functional ferroelectric devices. Here, we systematically investigated effects of various parameters during the growth of α-GeTe nanosheets on mica by APCVD. Single-crystal α-GeTe nanosheets possess a lateral size of up to ∼30 μm and a thickness as low as ∼8.6 nm. It was found that substrate pre-annealing significantly impacted the nucleation density of α-GeTe nanosheets. Furthermore, the room-temperature ferroelectric properties of α-GeTe nanosheets grown by CVD are reported for the first time. This work offers an effective accessible method for the controllable growth of large-size 2D α-GeTe to explore its fascinating multiferroic properties. [ABSTRACT FROM AUTHOR]

Polymer blends are regarded as a straightforward and effective method to enhance the energy storage performance of dielectric film capacitors. However, how the components and structures within the blend systems affect the energy density and efficiency remains insufficiently explored in-depth. In this discourse, employing a polymer blend of ferroelectric and linear dielectric phases as a paradigm, we perform phase-field simulations to elucidate the effects of ferroelectric phase volume fractions, geometrical dimensions, and the dielectric constant of the linear phase on the energy storage capabilities. Concurrently, we have devised six divergent blending microstructures to probe the ramifications of structural variances on the overarching performance metrics. We also analyze the domain configurations and switching dynamics under varying electric fields to understand the performance variations and delineate the determinants conducive to superior energy density and efficiency. This paper theoretically establishes the component–content–structure–performance relationships of different polymer blend systems, which is expected to better guide the innovative design of new polymer blend dielectrics. [ABSTRACT FROM AUTHOR]

Barium titanate ceramics with A- site and B-site substitutions are intriguing alternative to lead-based Pb (Zr, Ti) O3 (PZT) because of its comparable properties to soft-PZTs. In this paper, (BaxCa1-xSn0.09 Ti0.91) O3 (x = 0.0525, 0.0575, 0.060) ceramics are prepared using a solid-state reaction technique followed by microwave sintering at 1350 °C for 30 minutes. Structural and electrical properties are investigated. X -ray diffraction shows that the compositions exhibit a tetragonal crystal structure having P4mm symmetry. Temperature dependent dielectric constant measurements in the temperature range of 25 °C to 120 °C shows high dielectric constant of 26250 at 40kHz for BCST ceramics with x=0.0525 and the Curie temperature Tc increases with Ca concentration. The results of dielectric measurements as a function of frequency are also reported. The dielectric loss (tan δ) values in the temperature range 25 °C to 120 °C are observed to be less than 0.03, for all BCST ceramics. The AC conductivity, impedance spectroscopy studies and the conduction mechanism on the basis of Arrhenius plot are discussed in the above-mentioned temperature range. [ABSTRACT FROM AUTHOR]

Bismuth layer structured ferroelectrics (BLSFs) have drawn much attention due to their great potential for high‐temperature applications. It is generally accepted that BLSFs with small orthorhombic distortion should have low TC. In this paper, we report an anomalous example Li0.5Bi2.5Nb2O9 (LBN), which has small orthorhombic distortion but very high TC. LBN shows the highest TC (834°C) among currently reported prototype alkali‐metal BLSFs, which is attributed to its small tolerance factor. However, the refinement result reveals that LBN is orthorhombic with the space group of A21am, and the orthorhombic distortion of LBN a/b is merely 1.0019. The measurement of piezoelectric coefficient (d33 ∼ 6 pC/N) and observation of striped domain structure confirm the ferroelectricity nature of LBN. This work deepens our understanding of BLSFs and may lead to the finding of more novel BLSFs with high performance. [ABSTRACT FROM AUTHOR]

A correlation between ferroelectricity and grain sizes in atomic layer deposition (ALD)-derived Hf0.5Zr0.5O2 (HZO) thin films has been demonstrated through controlling process conditions. The influence of annealing temperature, annealing time and film thickness on the structural properties, ferroelectric performance and grain sizes was systematically investigated. A correlation diagram was constructed according to the different values of remnant polarization (Pr) and coercive field (Ec) in the different ranges of grain sizes. The Pr values displayed a continuous declining trend, and the Ec values firstly decreased and then increased with the increase of grain sizes. A strong size effect of ferroelectricity in the HZO thin films was proved through providing a simple annealing process or controlling the film thickness. The results showed that excellent ferroelectricity (∼15 μC cm−2) could be obtained with grain sizes in the range of 15–35 nm, which corresponded to the appropriate annealing conditions of 450 °C for 60 s with a film thickness of 10 nm. This paper can provide guidance for designing ferroelectric HfO2-based films with high performance through controlling grain sizes. [ABSTRACT FROM AUTHOR]

The use of refrigeration technology is widespread in national security, industrial and agricultural production, biomedicine, and everyday life. High efficiency, environmental friendliness, and low cost make solid-state refrigeration based on electrocaloric effect (ECE) a promising refrigeration technology. Lead-free ferroelectric ceramics (1–x)Ba(Zr0.2Ti0.8)O3–x(Ba0.7Ca0.3)TiO3 (BZT–BCT) are promising materials for electrocaloric refrigeration in the field. In this paper, Sm-doped 0.5BZT–0.5BCT ceramic was fabricated by the conventional solid-state reaction method. The effect of Sm-doping contents (0, 1.0, 2.0, 2.5, and 3.0 mol.%) on the phase structures, dielectric properties, ferroelectricity, and electrocaloric properties of 0.5BZT–0.5BCT ceramics was systematically examined. The results indicate that all ceramics have a pure perovskite structure with no other secondary phase available. High relative densities are observed in all lead-free ferroelectric ceramics and all of the samples show transgranular fracture with no clear grain boundaries seen. The ceramics' ferroelectric hysteresis loops become thinner as the Sm doping content increases. At that, remanent polarization Pr decreases, indicating that more polar nanoregions (PNRs) are formed in BZT–BCT lead-free ceramics through Sm doping. The increase in Sm doping content resulted in a change in the dielectric permittivity and electrocaloric temperature that first increased and then decreased. The maximum dielectric permittivity is 5,518 when the doping content of Sm is 2.5 mol.% and the maximum electrocaloric temperature change ΔTmax of 0.109 K at 4 kV/mm was obtained when Sm doping content was 2 mol.%. The results show that an appropriate Sm doping is favorable for improving the dielectric, ferroelectric, and electrothermal properties of lead-free ceramics 0.5BZT–0.5BCT. [ABSTRACT FROM AUTHOR]

Ferroelectric polymers are of great interest due to their intrinsic processing capabilities, superior to classic inorganic ferroelectric materials. For example, polyvinylidene fluoride (PVDF) and derivatives have been incorporated into multiple device architectures for information storage and transfer. Here we report an additional advantage of organic ferroelectrics as their flexibility allows for the preparation of composites with spin crossover (SCO) probes to tune their ferroelectric parameters by external stimuli. We demonstrate how the saturation polarization and coercive field of a ferroelectric [Fe(NH2trz)3](NO3)2/PVDF composite film depends on the spin state of the [Fe(NH2trz)3](NO3)2, opening a thermal hysteresis and delivering a ferroelectric material with a memory effect. This switching may now be used to tune the function of a device, adding additional information states to the elemental binary logic. Additional evidence of the synergy between the two components of these films was also found in the glass transition of the PVDF component that induces small changes in the paramagnetic component. [ABSTRACT FROM AUTHOR]

In this paper, a novel ferroelectric-based electrostatic doping (Fe-ED) nanosheet tunneling field-effect transistor (TFET) is proposed and analyzed using technology computer-aided design (TCAD) Sentaurus simulation software. By inserting a ferroelectric film into the polarity gate, the electrons and holes are induced in an intrinsic silicon film to create the p-source and the n-drain regions, respectively. Device performance is largely independent of the chemical doping profile, potentially freeing it from issues related to abrupt junctions, dopant variability, and solid solubility. An improved ON-state current and ION/IOFF ratio have been demonstrated in a 3D-calibrated simulation, and the Fe-ED NSTFET's on-state current has increased significantly. According to our study, Fe-ED can be used in versatile reconfigurable nanoscale transistors as well as highly integrated circuits as an effective doping strategy. [ABSTRACT FROM AUTHOR]

In this paper, barium titanate nanoparticles (BaTiO3, BT) were incorporated into the polyurethane (TPU) matrix to prepare dielectric elastomer composites. Then, the composites were thermal treated to improve the interfacial compatibility between TPU and BT, enhance the interface polarization, and improve the dielectric properties. The results showed that the dielectric constant of the composites after thermal treatment at 150°C reached to 7.3 at 1 kHz, the elongation at break remained 1934%, and the elastic modulus (Y) dropped to 4.4 MPa. In addition, the discharge energy density reached 73 mJ/cm3 under an electric field of 300 kV/cm, and charge–discharge energy conversion efficiency was up to 84%. More importantly, the electrically actuated displacement of 2.61 mm at electric field of 160 kV/cm was 1.7 times greater than that of untreated composites. The composites worked stably under the action of the circulating electric field. This study provided a new strategy for obtaining high‐performance dielectric elastomer actuators, which were expected to be applied to biomimetic robots, human skin, or dielectric energy storage devices. [ABSTRACT FROM AUTHOR]

The present paper reports the effect of Yttrium substitution on the structural, microstructure, dielectric, ferroelectric, and electrocaloric (EC) properties of the lead-free (Na0.5 Bi0.5)0.94 Ba0.06TiO3 (abbreviated as NBT-6BT) ceramics. For a small quantity of Yttrium (x = 0.01 and 0.05), the X-ray diffraction and Raman spectra exhibit the coexistence of rhombohedral and tetragonal phases at room temperature. However, with x = 0.08 composition, a structural change to pseudo-cubic phase was identified. By adding a small amount of Yttrium, the ferroelectric properties were improved by increasing the remnant polarization from (Pr = 27µC/cm2) for x = 0 up to (Pr = 36µC/cm2) for x = 0.01. This resulted in an improvement of 30% in the estimated ferroelectric parameters as well as an improvement in the piezoelectric properties, as measured by the value of d33 of 130 pC/N. The electrocaloric temperature change (ΔT) is calculated by a direct method using Differential Scanning Calorimetry (DSC) to be at more than 1 K at 5 kV/mm for x = 0.01. Despite the minimal amount employed, our observations lead us to say that the introduction of Yttrium into the NBT-6BT ceramic has directly affected the properties of this material. Nevertheless, with a higher content of Yttrium (x = 0.08), a sudden decrease of both ferroelectric and EC effect was observed. The declined properties at higher contents may originate from the structural change which can influence the polar distribution in the structure. [ABSTRACT FROM AUTHOR]

The paper presents the structural-energy, electrically conductive and polarization properties of biintercalant clathrate GaSe≪NaNO2> +3≫. The existence of two modifications of the crystal structure with interplanar distances c1 = 16.072 Å and c2 = 15.977 Å was established by X-ray diffractometry. The сurrent-voltage characteristics of the biitercalant clathrate GaSe≪NaNO2> +3≫ acquires a hysteresis form, which indicates the accumulation of electric charge at the interfacial boundaries. The spectrum of impurity energy levels was established by the method of thermally stimulated discharge with short-circuited contacts in the temperature range from 240 to 340 K, which testifies to the relaxation of the hetero-charge and the quasi-continuity of energy states. [ABSTRACT FROM AUTHOR]

In the last decade, Fe2Mo3O8 was recognized for a giant magnetoelectric effect, the origin of which is still not clear. In the present paper, we contribute to the microscopic theory of the magnetoelectric coupling in this compound. Using crystal field theory and the molecular field approximation, we calculated the low-lying energy spectrum for iron ions and their interaction with electric and magnetic fields. Classical ionic contribution to the electric polarization related to the ionic shifts is also estimated. It is found that the electronic and ionic contributions to the electric polarization are comparable and these mechanisms support each other at T < T N . The suggested electronic mechanism provides insight into the nature of huge jumps in polarization upon phase transitions from paramagnetic (PM) to antiferromagnetic (AFM) and then to ferrimagnetic (FRM) states under an applied external magnetic field as well as the large differential magnetoelectric coefficient. [ABSTRACT FROM AUTHOR]

With its excellent ferroelectric properties such as large dielectric constant and large remanent polarization, PZT thin films are extensively used in micro-sensors and other devices. In this study, the sol–gel process was used to fabricate Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1–x)O3 seed islands. The experimental consequences demonstrate that all the Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1−x)O3 seeds show pure perovskite phase with no other impurity phases, and the electrical properties of Pb(Zr0.52Ti0.48)O3 thin films modified by Pb(ZrxTi1–x)O3 seed islands with different Zr/Ti ratios are improved, such as remanent polarization increased, dielectric properties increased, coercive electric field decreased, leakage current density decreased. In particular, the electrical properties of the Pb(Zr0.52Ti0.48)O3 thin films with Pb(ZrxTi1–x)O3 seed islands are the most optimal when the x is 0.52. This paper provides a new technique for optimizing the electrical properties of PZT thin films, which is of great significance for breaking through the bottleneck of the development of ferroelectric memory. [ABSTRACT FROM AUTHOR]

The present paper reports the multifunctional properties of lead‐free BiFeO3–La (BFO–La) thin films. The structural, microstructural, and optical properties have been investigated as a function of the lanthanum doping concentration. The structural properties at room temperature showed the formation of the perovskite structure, thus suggesting the high quality of the obtained thin film compositions. Raman spectroscopy analysis revealed a slight variation in both the peak position and absolute intensity for the Raman active modes, as lanthanum content increases in BiFeO3–La. Crystallized thin films with well‐defined grains as well as crack‐free surfaces have been obtained, for all the studied compositions, as inferred from atomic force microscopy images. The optical properties have been measured, and the values for the direct bandgap was significantly lower than those reported for other BFO‐based systems, being the lowest ∼1.87 eV for the Bi0.90La0.10FeO3 composition. Results revealed a noteworthy effect of the defect concentrations induced by the lanthanum doping on the long‐range crystallinity and directly affecting the polarizability of the A–O bond as well as the Fe–O and Fe–O–Fe bond lengths in the perovskite structure. The enhanced optical absorption properties registered for the Bi1–xLaxFeO3 (x = 0–20) compositions make these perovskite multiferroic thin films as a potential candidate material for the high‐performance photovoltaic device applications. [ABSTRACT FROM AUTHOR]

Ferroelectricity and magnetism seldom coexist due to mutual exclusiveness. Recent attempts have been made to achieve the coexistence of ferroelectricity and magnetism in polar magnets. In this paper, we investigated the magnetic properties, dielectric relaxation, and magnetodielectric (MD) effect of polar Dy2Cu2O5 ceramic. At the antiferromagnetic ordering temperature, the dielectric constant (ɛ) curves exhibit a spontaneous change in slope, indicating strongly coupled charge and spin degrees of freedom. With increase in the magnetic field intensity, the simultaneous suppression of the dielectric anomaly and the antiferromagnetic transformation demonstrates the existence of the MD effect. It is important to note that ɛ varies nonmonotonically with the magnetic field. Below the magnetic ordering temperature, ɛ increases continuously before the metamagnetic transition and then decreases after that. The results are discussed in terms of the magnetic field-induced change of spin configuration and spin–phonon coupling. Moreover, two dielectric relaxation-related steps are observed, which are correlated with the electrons hopping within and among the zigzag chains of Cu2+, respectively. This work helps understand the dielectric behavior and the MD effect in materials with complicated spin structures. [ABSTRACT FROM AUTHOR]

This paper proposes a compact model for a top-gated negative capacitance-based carbon nanotube field-effect transistor (NC-CNTFET). The proposed model relies on a metal–ferroelectric–metal–insulator–semiconductor (MFMIS) configuration. A charge-based modelling approach is used for the top-gated CNTFET, where the surface charge of the CNT is calculated from chirality and gate bias. This charge is the same as the NC-CNTFET device's total charge, based on which the compact model for the proposed device is developed. The ferroelectric material of choice is hafnium silicon oxide (HfSiO). A comparison of the NC-CNTFET with the top-gated CNTFET (TG-CNTFET) is also shown. The results show an improved subthreshold slope and ON/OFF-current ratio in the NC-CNTFET because of the negative capacitance effect of the ferroelectric layer. The impact of different ferroelectric thicknesses is also shown, which suggests further improvement in device performance as the ferroelectric thickness increases. [ABSTRACT FROM AUTHOR]

The rapidly developing organic–inorganic hybrid chalcogenide solar cells have now become a hot topic of interest. However, the bandgap of inorganic ferroelectric materials with a typical chalcogenide structure is too wide to match the solar spectrum, while the ferroelectricity of organic-inorganic hybrid chalcogenide materials with a narrow bandgap, meth amide–lead–iodine, is not obvious, and the lead element causes environmental pollution. The recently discovered organic–inorganic hybrid material [C6N2H18]BiI5 with good ferroelectricity and the narrowest bandgap of molecular ferroelectrics can absorb visible light in the range of 380 nm to 660 nm, and compound [C6N2H18]SbI5 with the Bi cognate element Sb was also synthesized. In this paper, we designed the first experiment to prepare thin films by mixing and doping the above two materials in five different molar ratios, and we comparatively studied the changes in crystal structure, surface morphology, and photophysical properties of the prepared multicomponent hybrid films according to the mixing ratio. A theoretical model was developed to calculate and analyze the bandgap of the hybrid doped compounds and compare it with the experimental values. It was found that the absorption spectra of the multicomponent hybrid films were red-shifted relative to the original material, indicating that the forbidden bandwidth was reduced to absorb a wider range of visible light, and the reason for this was thought to be the narrowing of the bandgap due to doping. When the mixing ratio was 0.4:0.6, the bandgap was the narrowest and the light absorption was the best; the highest quality of the film was obtained when the mixing ratio was 0.5:0.5. [ABSTRACT FROM AUTHOR]

In the past decade, aluminum scandium nitride (AlScN) with a high Sc content has shown ferroelectric properties, which provides a new option for CMOS-process-compatible ferroelectric memory, sensors and actuators, as well as tunable devices. In this paper, the ferroelectric properties of A l 0.7 S c 0.3 N grown on different metals were studied. The effect of metal and abnormal orientation grains (AOGs) on ferroelectric properties was observed. A coercive field of approximately 3 MV/cm and a large remanent polarization of more than 100 μC/cm2 were exhibited on the Pt surface. The A l 0.7 S c 0.3 N thin film grown on the Mo metal surface exhibited a large leakage current. We analyzed the leakage current of A l 0.7 S c 0.3 N during polarization with the polarization frequency, and found that the A l 0.7 S c 0.3 N films grown on either Pt or Mo surfaces have large leakage currents at frequencies below 5 kHz. The leakage current decreases significantly as the frequency approaches 10 kHz. The positive up negative down (PUND) measurement was used to obtain the remanent polarization of the films, and it was found that the remanent polarization values were not the same in the positive and negative directions, indicating that the electrode material has an effect on the ferroelectric properties. [ABSTRACT FROM AUTHOR]

Electrically switchable bistable conductance that occurs in ferroelectric materials has attracted growing interest due to its promising applications in data storage and in‐memory computing. Sc‐alloyed III‐nitrides have emerged as a new class of ferroelectrics, which not only enable seamless integration with III‐nitride technology but also provide an alternative solution for CMOS back end of line integration. In this paper, the resistive switching behavior and memory effect in an ultrawide‐bandgap, high Curie temperature, fully epitaxial ferroelectric ScAlN/GaN heterostructure is reported for the first time. The structure exhibits robust ON and OFF states that last for months at room temperature with rectifying ratios of 60–210, and further shows stable operation at high temperatures (≈670 K) that are close to or even above the Curie temperature of most conventional ferroelectrics. Detailed studies suggest that the underlying mechanism is directly related to a ferroelectric field effect induced charge reconstruction at the hetero‐interface. The robust resistive switching landscape and the electrical polarization engineering capability in the polar heterostructure, together with the promise to integrate with both silicon and GaN technologies, can pave the way for next‐generation memristors and further enable a broad range of multifunctional and cross‐field applications. [ABSTRACT FROM AUTHOR]

The state-of-the-art CMOS technology has started to adopt three-dimensional (3D) integration approaches, enabling continuous chip density increment and performance improvement, while alleviating difficulties encountered in traditional planar scaling. This new device architecture, in addition to the efforts required for extracting the best material properties, imposes a challenge of reducing the thermal budget of processes to be applied everywhere in CMOS devices, so that conventional processes must be replaced without any compromise to device performance. Ultra-violet laser annealing (UV-LA) is then of prime importance to address such a requirement. First, the strongly limited absorption of UV light into materials allows surface-localized heat source generation. Second, the process timescale typically ranging from nanoseconds (ns) to microseconds (μs) efficiently restricts the heat diffusion in the vertical direction. In a given 3D stack, these specific features allow the actual process temperature to be elevated in the top-tier layer without introducing any drawback in the bottom-tier one. In addition, short-timescale UV-LA may have some advantages in materials engineering, enabling the nonequilibrium control of certain phenomenon such as crystallization, dopant activation, and diffusion. This paper reviews recent progress reported about the application of short-timescale UV-LA to different stages of CMOS integration, highlighting its potential of being a key enabler for next generation 3D-integrated CMOS devices. [ABSTRACT FROM AUTHOR]

In the doped hafnia(HfO2)-based films, crystallization annealing is indispensable in forming ferroelectric phases. In this paper, we investigate the annealing effects of TiN/Hf0.5Zr0.5O2/TiN metal-ferroelectric-metal (MFM) capacitors by comparing microwave annealing (MWA) and rapid thermal annealing (RTA) at the same wafer temperature of 500 °C. The twofold remanent polarization (2Pr) of the MWA device is 63 µC/cm2, surpassing that of the RTA device (40 µC/cm2). Furthermore, the wake-up effect is substantially inhibited in the MWA device. The orthorhombic crystalline phase is observed in the annealed HZO films in the MWA and RTA devices, with a reduced TiN and HZO interdiffusion in MWA devices. Moreover, the MFM capacitors subjected to MWA treatment exhibit a lower leakage current, indicating a decreased defect density. This investigation shows the potential of MWA for application in ferroelectric technology due to the improvement in remanent polarization, wake-up effect, and leakage current. [ABSTRACT FROM AUTHOR]

Many factors have been confirmed to affect ferroelectric phase formation in HfO2-based thin films but there was still a lack of general view on describing them. This paper discusses the intrinsic parameters to stabilize the ferroelectric phase of HfO2 thin films to approach this general view by investigating the separate effects of dopant, oxygen vacancy (VO), and specific surface area on the crystal phase of the films. It is found that in addition to extensively studied dopants, the ferroelectric orthorhombic phase can also be formed in pure HfO2 films by only introducing sufficient VO independently, and it is also formable by only increasing the specific surface area. By analyzing the common physics behind these factors, it is found that orthorhombic phase formation is universally related to strain in all the above cases with a given temperature. To get a general view, a physical model is established to describe how the strain influences ferroelectric phase formation during the fabrication of HfO2-based films based on thermodynamic and kinetics analysis. [ABSTRACT FROM AUTHOR]