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The chemical, physical, and electrical properties of the atomic layer deposited Hf0.5Zr0.5O2 thin films using tetrakis(ethylmethylamino) (TEMA) and tetrakis(dimethylamino) (TDMA) precursors are compared. The ligand of the metal-organic precursors strongly affects the residual C concentration, grain size, and the resulting ferroelectric properties. Depositing Hf0.5Zr0.5O2 films with the TDMA precursors results in lower C concentration and slightly larger grain size. These findings are beneficial to grow more ferroelectric-phase-dominant film, which mitigates its wake-up effect. From the wake-up test of the TDMA-Hf0.5Zr0.5O2 film with a 2.8 MV/cm cycling field, the adverse wake-up effect was well suppressed up to 105 cycles, with a reasonably high double remanent polarization value of ~40 μC/cm2. The film also showed reliable switching up to 109 cycles with the 2.5 MV/cm cycling field without involving the wake-up effect but with the typical fatigue behavior.

Memristors have attracted increasing attention due to their tremendous potential to accelerate data-centric computing systems. The dynamic reconfiguration of memristive devices in response to external electrical stimuli can provide highly desirable novel functionalities for computing applications when compared with conventional complementary-metal–oxide–semiconductor (CMOS)-based devices. Those most intensively studied and extensively reviewed memristors in the literature so far have been filamentary type memristors, which typically exhibit a relatively large variability from device to device and from switching cycle to cycle. On the other hand, filament-free switching memristors have shown a better uniformity and attractive dynamical properties, which can enable a variety of new computing paradigms but have rarely been reviewed. In this article, a wide range of filament-free switching memristors and their corresponding computing applications are reviewed. Various junction structures, switching properties, and switching principles of filament-free memristors are surveyed and discussed. Furthermore, we introduce recent advances in different computing schemes and their demonstrations based on non-filamentary memristors. This Review aims to present valuable insights and guidelines regarding the key computational primitives and implementations enabled by these filament-free switching memristors.

This paper evaluates the effect of construction quality defects on the seismic vulnerability of reinforced concrete (RC) frames. The variability in the construction quality of material properties and structural detailing is considered to assess the effect on the seismic behavior of RC frames. Concrete strength and yield strength of the reinforcement are selected as uncertain variables for the material properties, while the variabilities in the longitudinal reinforcement ratio and the volumetric ratio of transverse reinforcement are employed for structural detailing. Taking into account the selected construction quality uncertainties, the sensitivity analysis of the seismic vulnerability of the RC frames is performed and the impact of significant parameters is assessed at the global and local levels. This extensive analytical study reveals that the seismic vulnerability of the selected RC frame is particularly sensitive to concrete strength and the volumetric ratio of transverse reinforcement.

Enhancement of capacitance by negative capacitance (NC) effect in a dielectric/ferroelectric (DE/FE) stacked film is gaining a greater interest. While the previous theory on NC effect was based on the Landau-Ginzburg-Devonshire theory, this work adopted a modified formalism to incorporate the depolarization effect to describe the energy of the general DE/FE system. The model predicted that the SrTiO 3 /BaTiO 3 system will show a capacitance boost effect. It was also predicted that the 5 nm-thick Al 2 O 3 /150 nm-thick BaTiO 3 system shows the capacitance boost effect with no FE-like hysteresis behavior, which was inconsistent with the experimental results; the amorphous-Al 2 O 3 /epitaxial-BaTiO 3 system showed a typical FE-like hysteresis loop in the polarization – voltage test. This was due to the involvement of the trapped charges at the DE/FE interface, originating from the very high field across the thin Al 2 O 3 layer when the BaTiO 3 layer played a role as the NC layer. Therefore, the NC effect in the Al 2 O 3 /BaTiO 3 system was frustrated by the involvement of reversible interface charge; the highly stored charge by the NC effect of the BaTiO 3 during the charging period could not be retrieved during the discharging process because integral part of the polarization charge was retained within the system as a remanent polarization.

Negative differential capacitance in ferroelectrics, which can be stabilized using a dielectric, could be used to overcome the limitations of capacitive coupling in electronic devices. However, the use of negative differential capacitance in scaled silicon-based structures—such as those used in advanced low-power logic devices—remains challenging. Here we report the electrical performance enhancement due to negative differential capacitance in metal–oxide–semiconductor capacitors based on ferroelectric zirconium-doped hafnia (Hf 0.5 Zr 0.5 O 2 ) with a thickness down to 1 nm. The devices exhibit superior performance to physically thinner control devices without the ferroelectric zirconium-doped hafnia. An S-shaped polarization–electric field relation verifies the negative differential capacitance effect. The effect is also achieved in field-effect transistors in which high- κ hafnia is replaced with the ferroelectric zirconium-doped hafnia, leading to an increase in on current and decrease in off current along with negative drain-induced barrier lowering. The negative differential capacitance exhibits endurance over more than 10 15  cycles and can be tuned using doping that controls the interface charges. Ferroelectric zirconium-doped hafnia (Hf 0.5 Zr 0.5 O 2 ) can be used to create negative differential capacitance behaviour in capacitors and transistor gate stacks, providing reliable enhancements in switching performance.

Ferroelectric HfO2‐based films incorporated in nonvolatile memory devices offer a low‐energy, high‐speed alternative to conventional memory systems. Oxygen vacancies have been rigorously cited in literature to be pivotal in stabilizing the polar noncentrosymmetric phase responsible for ferroelectricity in HfO2‐based films. Thus, the ability to regulate and control oxygen vacancy migration in operando in such materials would potentially offer step changing new functionalities, tunable electrical properties, and enhanced device lifespan. Herein, a novel in‐ operando approach to control both wake‐up and fatigue device dynamics is reported. Via clever design of short ad hoc square electrical pulses, both wake‐up can be sped up and both fatigue and leakage inside the film can be reduced, key factors for enhancing the performance of memory devices. Using plasmon‐enhanced photoluminescence and dark‐field spectroscopy (sensitive to <1% vacancy variation), evidence that the electrical pulses give rise to oxygen vacancy redistribution is provided and it is shown that pulse engineering effectively delays wake‐up and reduces fatigue characteristics of the HfO2‐based films. Comprehensive analysis also includes impedance spectroscopy measurements, which exclude any influence of polarization reversal or domain wall movement in interpretation of results. Short electrical pulses to “reset” VO migration in ultrathin ferroelectric oxides are engineered. Electrical pulse modification regulates wake‐up, reduces fatigue, and leakage. Reset waveforms exhibit ability to control wake‐up by ≈4× to ≈24×, retard fatigue by 2× to 4×, and minimize leakage by ≈60%. Photoluminescence and dark‐field spectroscopy show strong evidence that this is linked to film VO control.

Recent claim on the direct observation of a negative capacitance (NC) effect from a single layer epitaxial Pb(Zr 0.2 ,Ti 0.8 )O 3 (PZT) thin film was carefully reexamined, and alternative interpretations that can explain the experimental results without invoking the NC effect are provided. Any actual ferroelectric capacitor has an interfacial layer, and experiment always measures the sum of voltages across the interface layer and the ferroelectric layer. The main observation of decreasing ferroelectric capacitor voltage (V F ) for increasing ferroelectric capacitor charge (Q F ), claimed to be the direct evidence for the NC effect, could be alternatively interpreted by either the sudden increase in the positive capacitance of a ferroelectric capacitor or decrease in the voltage across the interfacial layer due to resistance degradation. The experimental time-transient V F and Q F could be precisely simulated by these alternative models that fundamentally assumes the reverse domain nucleation and growth. Supplementary experiments using an epitaxial BaTiO 3 film supported this claim. This, however, does not necessarily mean that the realization of the NC effect within the ferroelectric layer is impractical under appropriate conditions. Rather, the circuit suggested by Khan et al . may not be useful to observe the NC effect directly.

We have measured the dynamical response of ZrO2 capacitors to applied triangular voltage waveforms with varying frequencies and amplitudes to determine the voltage and charge on the devices as a function of time. We have fit our experimental results to a Landau–Khalatnikov dynamical equation with a sixth order Landau–Ginzburg–Devonshire polynomial to represent the static charge-voltage behavior, and obtained coefficients of determination R2 > 0.99 for the fits. Analysis of the resulting quantitative model reveals an extremely small range of negative differential capacitance <16 mV. The hysteresis loops in the dynamical charge-voltage curves are found to result primarily from energy loss during the ferroelectric transitions, as represented by a frequency-dependent series resistance in the model.

Recent years have witnessed the development of single-molecule localization microscopy as a generic tool for sampling diverse biologically relevant information at the super-resolution level. While current approaches often rely on the target-specific alteration of the point spread function to encode the multidimensional contents of single fluorophores, the details of the point spread function in an unmodified microscope already contain rich information. Here we introduce a data-driven approach in which artificial neural networks are trained to make a direct link between an experimental point spread function image and its underlying, multidimensional parameters, and compare results with alternative approaches based on maximum likelihood estimation. To demonstrate this concept in real systems, we decipher in fixed cells both the colors and the axial positions of single molecules in regular localization microscopy data. Single-molecule methods often rely on point spread functions that are tailored to interpret specific information. Here the authors use a neural network to extract complex PSF information from experimental images, and demonstrate this by classifying color and axial positions of emitters.

Bacterial vaginosis (BV) is the most common vaginal infection in reproductive women, which is characterized by depleted level of lactic acid bacteria and overgrowth of anaerobes such as Gardnerella vaginalis spp. Lactic acid bacteria have been known to be beneficial for amelioration of BV, since they produce antimicrobial substances against G. vaginalis spp. The objectives of this study were to characterize different fractions of cell-free supernatant of Lactobacillus paracasei CH88 (LCFS) and investigate antibacterial activity of the LCFS fractions against G. vaginalis in-vitro and in-vivo. Antibacterial activity of the LCFS was stable during thermal treatment up to 120 °C for 30 min and maintained at pH ranging from 3.0 to 13.0 except pH 5.0. Fraction below 3 kDa of the LCFS partially lost its antibacterial activity after treatment with proteolytic enzymes. Precipitated protein fraction below 3 kDa of the LCFS (< 3 kDa LCFSP) inhibited the growth and biofilm formation of G. vaginalis . Treatment of L. paracasei CH88 or the < 3 kDa LCFSP attenuated G. vaginalis -induced BV in mice by inhibiting the growth of G. vaginalis , reducing exfoliation of vaginal epithelial cells, and regulating immune response. These results suggest that L. paracasei CH88 may have potential in ameliorating G. vaginalis -induced BV.