Search

Domain wall current (DWC) plays a key role in storage devices, logic devices and sensors due to its high on-off ratio and nano structure size in the era of nanoelectronics technology. In this work, the DWC of single crystal LiNbO3 thin film was studied by piezoresponse force microscope (PFM) and conducting atomic force microscope (c-AFM). We mainly focus on voltage and temperature dependence of DWC which increases with the voltage and temperatures. Based on this research, the packaged DWC temperature sensor is fabricated and applied in wide temperature range. The existence of domain walls makes the current on-off ratio as high as 103 at the voltage of 15 V. Our study shows that DWC has a negative temperature coefficient (NTC) from 140 K to 500 K. The current increases from 3 pA to $57 ~\mu \text{A}$ , which is attributed to the conductivity of switched domain. This work proposes a new type temperature sensor with wide temperature range and high compatibility and sensitivity. In addition, it provides support for harsh environment applications of ferroelectric domain engineering devices. [ABSTRACT FROM AUTHOR]

High-quality ferroelectric films of Mn-doped Pb(Zr 0.3 Ti 0.7)O 3 (PMZT) were prepared using the sol-gel method, and the temperature dependence of ferroelectric, dielectric, and leakage current properties (J – E) were explored in detail using the top electrode/ferroelectric films/bottom electrode capacitor heterostructure. The enhancement of polarization and dielectric properties by element doping is clearly observed by 3% Mn-doping. Such enhancement is beneficial for the application of these films in ferroelectric random-access memory. In addition, the analysis of leakage current reveals symmetric behavior with 3% Mn-doping and the leakage current density gradually increases with increasing temperature, which may be due to the movement of domain wall and oxygen vacancy. The dominant leakage current conduction mechanism is bulk-limited ohmic or interface-limited Schottky emission conduction within a wide temperature range. The results might be meaningful for further work on ferroelectric electrical devices with improved ferroelectric and dielectric properties. [ABSTRACT FROM AUTHOR]

Lithium niobate on insulator (LNOI) is widely used in optical, acoustic, domain wall current (DWC)-based integrated circuits and other domain engineering devices, enabling higher material performance, higher domain integration density and more advanced applications. However, there are hidden dangers of thermal failure in these highly integrated domain engineering devices. Therefore, maintaining thermal stability of domain structures in ferroelectric single-crystal thin films is an important and challenging task. Here, thermally induced structure reconstruction of tailored metastable switched domains was research in a 500 nm thick congruent lithium niobate (CLN) thin film, and a method for enhancing the thermal stability of switched domains was proposed. Piezoresponse force microscopy (PFM) and a polyheater are used to accurately monitor the thermal evolution of switched domains in CLN thin film sample. The results indicate the switched domain structures determine the thermal stability, and the enhanced thermal stability of the switched domains increases from 55 to 85 °C–150 °C. In this contribution, the thermal failure in domain engineering devices can be avoided effectively. The investigation paves the way for the development of domain engineering devices based on lithium niobate (LN) thin films. [ABSTRACT FROM AUTHOR]

[Display omitted] • Si-based LiNbO 3 films with the thickness 6.294 μm and roughness 585 pm are obtained by chemical mechanical polishing; • Oxygen plasma treatment reduced the water contact angle of the metal surface and improved the bonding strength; • Chemical mechanical polishing releases the compressive stresses that remain inside the wafer during the bonding; • Large-area ferroelectric domain with a period of 40 μm were reversed at the electric field of 320 kV/cm. In the post Moore era, as the size miniaturization approaches limit of the devices, silicon-based sensors cannot meet the requirements of micro/nano sensing with small size and high precision. The piezoelectric sensor based on lithium niobate (LN) single crystal thin film has excellent electromechanical property, photoelectric property, piezoelectric property, which can realize high precision sensing at small size. In our work, 4-inch silicon-based LN single crystal thin film was prepared based on low-temperature bonding technology and chemical mechanical polishing (CMP) method. The oxygen plasma treatment was adopted for increasing the surface hydrophilia to enhance the bonding strength. Grinding parameters under different film thickness were determined by experiments. The parameters of the film was characterized by scanning electron microscope (SEM) with a thickness of 6.294 μm and by atomic force microscope (AFM) obtained the surface roughness is 585 pm. The x-ray diffraction (XRD) test showed that the CMP process could release the compressive stress caused by the bonding, thus obtaining high quality LN single crystal films. The prepared films are polarized and the domain walls can be clearly observed by piezoresponse force microscopy (PFM). It provides a more comprehensive way to prepare ferroelectric domain devices. [ABSTRACT FROM AUTHOR]

• Negative electrocaloric effect (ECE) could be obtained in PLZ thin films within wide temperature range (213–493 K). • Giant negative ECE (Δ T ≈ −13.2 K) and entropy change (Δ S ≈ −11.5 J K−1 kg−1) could be obtained in PLZ thin films. • The combination between negative and positive ECE promotes cooling efficiency during electrical bias processing. Antiferroelectric thin films have exhibited outstanding negative electrocaloric effect (ECE), which are potential candidate regarding to the solid-state refrigeration technology. In this work, Pb 0.97 La 0.02 ZrO 3 (PLZ) antiferroelectric thin films were prepared on LaNiO 3 (LNO)/Pt electrode and LNO electrode by sol-gel method. Giant negative electrocaloric effect (Δ T ~ −13.2 K) can observed in wide temperature range (213–493 K) that deposited on composite electrode, which can be attributed to better electric conductivity of LNO/Pt composite electrode than LNO electrode. In addition to outstanding negative ECE, positive ECE also can be obtained near curie temperature, which is caused by phase transition from ferroelectric (FE) to paraelectric (PE) state. The optimized ECE property contributed to the phase transition and introduction of composite electrode, which pave the giant prospect considering high-efficiency solid-state refrigeration devices through combination of positive and negative ECE. [ABSTRACT FROM AUTHOR]

• The flexible film was prepared by combining the controlled spalling technique with dry etching method. • The original substrate can be recycled, which conducive to saving resources. • The recoverable energy storage of flexible film increased by 21% at 500 kV/cm compared to that of the original substrate. • The energy storage characteristics of the flexible film were tested under wide temperature environment (−70 °C −200 °C). Flexible energy-storage capacitor has attracted great attention due to deformable and lightweight, which could be applied to wearable electronics, bendable smartphones. It is urgent to manufacture a capacitor combining excellent electrical properties with mechanical bending capacity. Here, flexible Pb 0.97 La 0.02 Zr 0.95 Ti 0.05 O 3 (PLZT 2/95/5) films are prepared by controlled spalling technology (CST) and exhibit outstanding electrical properties with polarization about 86.3 µC/cm2 at various tensile or compressive bending radii, which indicates excellent mechanical stability of films. It is worth mentioning that recoverable energy-storage density (W re) of films has increased by 21% at 500 kV/cm compared to the original substrate, which is caused by change in stress. Meanwhile, flexible films were measured under wide temperature range from −70–200 °C with W re fluctuating from 9.2 J/cm3 to 17.1 J/cm3, which is related to free energy barrier of phase transition. These studies provide reference for preparation of flexible capacitors which have great potential applications for future flexible micro-devices. [ABSTRACT FROM AUTHOR]

Owing to their high remanent polarization, fast switching behavior, and controllable preparation process, Pb(Zr 0·3 Ti 0.7)O 3 (PZT) thin films are considered to be one of the most promising materials for non-volatile ferroelectric random access memory (FRAM). In this work, high-quality PZT thin films with a preferred (111) orientation and smooth surface are obtained by the sol–gel method. The temperature dependence of the ferroelectricity and domain switching behavior is thoroughly investigated by piezoresponse force microscopy (PFM). The domain structure undergoes distinct 180° switching and reconstruction under an external DC voltage. Polarization hysteresis loop analysis of PZT reveals that the spontaneous polarization (P s), remanent polarization (P r), and coercive voltage (V c) decrease as the temperature increases from 20 to 70 °C, in agreement with the Landau classical theory of phase transition. In addition, the PFM results show that the PZT films consistently exhibit good switching behavior as the temperature increases from 23.7 to 70 °C. An increase in the piezoelectric constant (D max) with increasing temperature is ascribed to more rapid domain wall movement and easier domain reorientation, as predicted by thermodynamic theory. This investigation suggests that the temperature strongly affects the ferroelectricity and switching behavior of PZT thin films and offers guidance for the design of FRAM. [ABSTRACT FROM AUTHOR]

Because of high temperature process, it has been a challenge to fabricate flexible piezoelectric or ferroelectric devices based on PbZr 0.53 Ti 0.47 O 3 (PZT). In this work, a high-quality flexible PZT film is successfully fabricated by the controlled spalling technology (CST). The PZT film deposited on sapphire substrate using sol-gel method is transferred onto a flexible polyimide (PI) substrate through electroplating Ni stressor layer, realizing the flexible heterogeneous integration of PZT film and PI substrate. The obtained PZT film exhibits a good crystalline perovskite structure and a smooth surface before and after spalling process. The ferroelectric response of the spalled PZT film based on Au/PZT/Au structure does not show obvious deterioration under different mechanical deformation, which indicates good ferroelectric property and stable mechanical performance. Further, the film on flexible Ni layer has the better piezoelectric property compared with that on conventional rigid Pt/Ti/SiO 2 /Si substrate. This work has the important significance for the development of flexible ferroelectric and piezoelectric devices like sensors, memorizers and nanogenerators. • High-quality PZT film on sapphire is successfully transferred onto flexible PI by CST. • Ferroelectric performance of spalled PZT film does not deteriorate after deformation. • The spalled PZT film on flexible Ni layer has a better piezoelectric property. [ABSTRACT FROM AUTHOR]