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Exploring the unique physical properties of oxide perovskites necessitates their growth on diverse single‐crystal substrates. The thin‐film growth of perovskite SrMnO3 (SMO) has been a particular focus of research due to its emerging room‐temperature multiferroicity. Herein, the epitaxial thin films of (110)‐oriented SMO are grown on the piezoelectric (110)‐oriented (1–x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN‐PT) substrate. The effects of the thickness and oxygen annealing on the crystal structure, stoichiometry, and ferroelectric properties of the SMO thin film are systematically investigated. The tensile strain produced by the lattice mismatch between the bulk SMO and the PMN‐PT substrate causes an expansion of the c‐lattice parallel to the in‐plane direction of the substrate. The films show larger a‐, b‐, and c‐lattice parameters than the bulk material, resulting in volume expansion of the unit cell. This lattice expansion is attributed to the generation of oxygen vacancies driven by the reduced formation energy caused by the high elastic strain. Piezoelectric force microscopy reveals that the SMO film contains domains with strain‐mediated in‐plane and vacancy‐mediated out‐of‐plane polarization. Furthermore, the piezoelectric response of the PMN‐PT substrate effectively modulates the biaxial tensile strain in the SMO film, offering a potential strategy for controlling the crystal structure and ferroelectric properties of SMO. [ABSTRACT FROM AUTHOR]

Ferroelectricity in HfO2 thin films can be utilized for fast, power‐efficient, and highly scalable non‐volatile memories. However, the required wake‐up process for inducing ferroelectricity/ achieving higher polarization is one of the major hurdles that hinder HfO2‐based thin films from developing reliable electronic devices. The wake‐up effect is believed to originate from i) phase transformation from non‐ferroelectric to ferroelectric, ii) movement of defect entities (mainly oxygen vacancy defects) near the film‐electrode interface, and iii) heterogeneity of the electrode interfaces. In the present study, an experimental strategy is designed to overcome these sources of the wake‐up process. A multi‐step deposition and annealing process is carried out to induce wake‐up‐free ferroelectricity in Yttrium doped HfO2 (Y:HfO2) thin film directly grown on Si‐substrate. Furnace annealing is utilized instead of the standard rapid thermal annealing process to reduce the oxygen deficiencies and stimulate the direct growth of the polar Y:HfO2. The oxygen‐vacancy‐related defects are found to be the dominating source of wake‐up effect in Y‐doped HfO2 films. The step‐wise deposition and annealing in the oxygen atmosphere facilitate direct growth of the polar phase, reduce the oxygen vacancies, and induce wake‐up‐free ferroelectricity in Y:HfO2. [ABSTRACT FROM AUTHOR]

A 17 nm thick PbTiO3 (PTO) films were fabricated via PbO gas phase reaction with TiO2 starting layer in a sputtering chamber. The influence of deposition temperature of TiO2 on the piezoelectric properties of PTO thin films was investigated. The remnant piezoresponse of PTO films nonlinearly increased as a function of TiO2 deposition temperature, which is correlated with the increase in average grain diameter of PTO film. As grain size increases, the restriction on remnant piezoresponse imposed by the grain boundary via coupling between local strain and polarization becomes less pronounced, which results in the increase in remnant piezoresponse. Furthermore, we found that the vertical shift in piezoresponse hysteresis loops is closely related to the residual stress state. A strong correlation between the negative vertical shift and the residual tensile stress reveals that residual stress on the resulting PTO film contributed to the asymmetric piezoelectric property. [ABSTRACT FROM AUTHOR]

We have studied the effect of local surface potential distribution on its relaxation in the polycrystalline ferroelectric thin films. A lower surface potential region, i.e., potential pit, is generated near a grain boundary. The deep potential pit has a faster relaxation than the area far away from the potential pit due to the acceleration of the screen charge draining near the grain boundary and the domains formed by applying higher voltage have a faster relaxation due to the larger gradient of screen charge distribution. In addition, the surface potential and its relaxation depend on the sign of applying voltage. The result shows that the surface potential distribution may influence significantly to the reliability of bit signal on the memory devices. [ABSTRACT FROM AUTHOR]

Here, we present a direct observation of fatigue phenomena in epitaxially grown Pb(Zr0.2Ti0.8)O3 (PZT) thin films using second harmonic piezoresponse force microscopy (SH-PFM). We observed strong correlation between the SH-PFM amplitude and phase signals with the remnant piezoresponse at different switching cycles. The SH-PFM results indicate that the average fraction of switchable domains decreases globally and the phase delays of polarization switching differ locally. In addition, we found that the fatigue developed uniformly over the whole area without developing region-by-region suppression of switchable polarization as in polycrystalline PZT thin films. [ABSTRACT FROM AUTHOR]

Here we introduce angle-resolved piezoresponse force microscopy (AR-PFM), whereby the sample is rotated by 30° increments around the surface normal vector and the in-plane PFM phase signals are collected at each angle. We obtained the AR-PFM images of BaTiO3 single crystal and cube-on-cube epitaxial (001) BiFeO3 (BFO) thin film on SrRuO3/SrTiO3 substrate, and confirmed that the AR-PFM provides more unambiguous information on the in-plane polarization directions than the conventional PFM method. Moreover, we found eight additional in-plane polarization variants in epitaxial BFO thin films, which are formed to mitigate highly unstable charged domain boundaries. [ABSTRACT FROM AUTHOR]

Using Kelvin force microscopy, the authors have investigated the potential distribution on ferroelectric films. The local distribution of potential was observed on downward, prepoled areas. The polarity of the potential corresponds to the screen charge. It was found that the electrical properties of the grain boundary affect the potential distribution. Most of the grain boundaries show a lower potential than the area inside the grain. The authors identified certain regions at the grain boundary with a very low potential. Such potential pits may act as efficient screen charge draining paths and may lead to important perturbations on the device level. [ABSTRACT FROM AUTHOR]

The authors have investigated the polarization reversal on ferroelectric thin films caused by a grounded tip on 50-nm-thick Pb(Zr,Ti)O3 films. Backswitching occurred when the grounded tip recontacted a “freshly” switched area. It is believed that the upper part of the film switches back due to the field between the grounded tip and previously injected charges. During dynamic operation, partial backswitching was observed during pulsed writing using pulse widths of 1 ms. The results show that polarization reversal is an issue, which has to be addressed in the writing scheme of future probe-based storage devices. [ABSTRACT FROM AUTHOR]

Despite the significant advancements of dielectric materials, the energy density values of dielectric capacitors are extremely low compared to those of other energy storage systems, e.g., batteries and fuel cells. The deposition of solid solution of ferroelectric and paraelectric multicomponent thin films are the most widely used approach to enhance the energy density of dielectric capacitors; however, it is extremely difficult to determine the optimized composition ratio of two or three components. In this study, we develop ultrahigh energy density single-component Sn-doped BaTiO 3 (BTS) epitaxial thin film capacitors. An ultrahigh energy density of 92.5 J/cm3 and energy efficiencies above 78% were successfully achieved in (111)-oriented BTS epitaxial thin film capacitors. These excellent results were attributed to the formation of multi-nanodomains accompanied by delayed polarization saturation, low remnant polarization, high breakdown strength, and high cycling stability. Engineering multi-nanodomains through chemical doping and epitaxial orientation is a facile approach to develop energy-efficient ultrahigh energy density capacitors. This approach can be extended for the design of other single-component-based energy-efficient dielectric capacitors with ultrahigh energy density. [Display omitted] [ABSTRACT FROM AUTHOR]