Development of PZT sputtering method for mass-production

(104)-oriented Bi4Ti3O12, La-substituted Bi4Ti3O12[(Bi3.44La0.56)Ti3O12] and Nd-substituted Bi4Ti3O12[(Bi3.54Nd0.46)Ti3O12] films were epitaxially grown on (111)SrRuO3//(111)SrTiO3 substrates at 700 °C by metalorganic chemical vapor deposition. All deposited films showed strong (104) orientations. The values of the remanent polarization (Pr) and coercive field (Ec) of the (104)-oriented epitaxial (Bi3.54Nd0.46)Ti3O12 thin film were 25 μC/cm2 and 135 kV/cm, respectively. This Pr value was larger than that of the (104)-oriented (Bi3.44La0.56)Ti3O12 film: Pr and Ec values of the (Bi3.44La0.56)Ti3O12 were 17 μC/cm2 and 145 kV/cm, respectively. These good ferroelectric properties of (Bi3.54Nd0.46)Ti3O12 films can be explained by a large tilting of TiO6 octahedra induced by the substitution of Nd3+, the ionic radius of which is smaller than that of La3+. Moreover, this Pr value is almost equal to that of commercially used lead zirconate titanate (PZT) films for nonvolatile ferroelectric random access memory (FeRAM) applications. These (104)-oriented epitaxial (Bi3.54Nd0.46)Ti3O12 thin films also showed a fatigue-free character. As a result, lead-free Nd-substituted Bi4Ti3O12 films with good ferroelectric properties comparable with those of PZT films are useful candidates for FeRAM applications.

Fabrication of Al0.01Ba0.99TiO3 (Al-BTO) thin films on SrTiO3/MgO/TiO2/SiO2/Si (STO/MgO) and MgO/TiO2/SiO2/Si (MgO) substrates were comparatively prepared using pulsed laser deposition (PLD). The structures of the prepared thin films were studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The SrTiO3 buffer layer between Al-BTO thin film and MgO substrate enhanced the ferroelectric, electrical properties. Moreover, the P-E loops showed a dramatic enhancement in the polarization values from 18 μC/cm2 at 600 kV/cm to 52 μC/cm2 at 780 kV/cm for Al-BTO thin films on SrTiO3/MgO and MgO substrates, respectively. In addition, the dielectric SrTiO3 buffer layer decreased the leakage current from 3 × 10−3 to 12 × 10−6 A/cm2 and increased breakdown electric field from 10 to 30 kV/cm. The electric properties revealed that, the dielectric SrTiO3 buffer layer also decreased the conductivity, mobility and carrier concentrations. The data of Al-BTO thin films on SrTiO3/MgO substrate exhibited remarkably adjusted polarization and leakage current indicating a good ferroelectric property for non-volatile ferroelectric random access memory (FERAM) applications.

Effects of annealing atmosphere on microstructure and ferroelectric properties of praseodymium-doped Bi 4Ti 3O 12 thin films prepared by sol–gel method

Ferroelectric (PBZ) thin films with different ratio were fabricated by a sol-gel process. Electrical properties of PBZ films on substrates (metal/ferroelectric/metal structure) and on substrates metal/ferroelectric/insulator/semiconductor (MFIS) structure were investigated. The dielectric and ferroelectric properties depend greatly on the ratio of the PBZ films. For the MFIS structure, the film shows the best memory property with memory window of when it was scanned at . Experimental results demonstrate that ferroelectric PBZ films with -buffered MFIS structure is suitable for non-volatile field effect transistor-type ferroelectric random access memory applications.

Ferroelectric Bi3.6La0.4Ti3O12 (BLT) and Mn-doped (0.1 wt%, 0.2 wt%, and 0.3 wt%) BLT thin films were prepared by sol-gel processing. In the X-ray diffraction (XRD) results, all films exhibited a randomly oriented perovskite phase. Concerning surface morphology, the grain boundaries of the Mn-doped (0.2 wt%) BLT thin film are more closely packed than those of the nondoped BLT film without the presence of many crevices and cracks around the grain boundaries due to the volatilization of the Bi components at high temperature. The remanent polarization of the stoichiometric, 0.1 wt%, 0.2 wt% and 0.3 wt% Mn-doped BLT films annealed at a heating rate of 50°C/h, were 14 µC/cm2, 18 µC/cm2, 31 µC/cm2 and 13 µC/cm2, respectively. The 0.2 wt% Mn-doped BLT thin film is a good candidate for ferroelectric memory cells and nonvolatile random access memory (NvRAM) applications.

Ferroelectric Ce-doped Bi₄Ti₃O₁₂ (BCT) thin films were deposited by liquid delivery metal organic chemical vapor deposition (MOCVD) onto a Pt(111)/Ti/SiO₂/Si(100) substrate. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure, the surface, and the cross-section morphology of the deposited ferroelectric films. After annealing above 640℃, the BCT films exhibited a polycrystalline structure with preferred (00l) and (117) orientations. The BCT film capacitor with a top Pt electrode showed a large remnant polarization (2P r ) of 44.56 μC/㎠ at an applied voltage of 5 V and exhibited fatigue-free behavior up to 1.0×10¹¹ switching cycles at a frequency of 1 ㎒. This study clearly reveals that BCT thin film has potential for application in non-volatile ferroelectric random access memories and dynamic random access memories.

Ferroelectric thin film capacitors are promising candidates for non-volatile ferroelectric Random Access Memories (FeRAM's) as they exhibit a switchable polarization. There are three important failure-mechanisms influencing the performance of these capacitors and disturbing the long-term stability and reliability under operation conditions fatigue, retention, and imprint. The imprint effect of lead zirconate titanate (PZT) thin films was investigated in this paper. Establishing and maintaining a polarization state leads to a shift of the hysteresis loop on the voltage axis and also to a loss of polarization. The voltage shift as well as the loss of polarization can cause a failure of the ferroelectric memory cell (read and write failure). The experimental results obtained on PZT films are discussed in view of the predictions of imprint models proposed in the literature.

Raman scattering has proven to be extremely useful for studies of phase transitions in ferroelectric materials and, in particular, as a tool to characterize soft modes [1] and features related to order-disorder phenomena [2]. The dynamical behavior of phase transitions and their sensitivity to temperature and doping can be easily elucidated by Raman scattering measurements [3–5]. The perovskite (ABO3) ferroelectric materials in thin-film form are of considerable interest, particularly for non-volatile ferroelectric random access memory and microwave devices. The ferroelectric properties depend strongly on film preparation, chemical composition and microstructures (crystal structures, orientation, grain size, domain structure, and surface roughness). Micro-Raman scattering from ferroelectric thin films provides a useful link between the phonon spectrum and the microstructure of the film.

The Influence of Vanadium Doping on the Physical and Electrical Properties of Non-Volatile Random Access Memory Using the BTV, BLTV, and BNTV Oxide Thin Films

The results of the studies of the features of integrating the elements of nonvolatile ferroelectric random access memory (FRAM) with CMOS technology are presented. The possibility and prospects of using their nanosized layers in the elements of nonvolatile FRAM are demonstrated.

Robust in-plane polarization switching in epitaxial BiFeO3 films

Summary form only given, as follows. Non-volatile ferroelectric random access memories (FRAMs) have widely studied for communication products and smart cards due to low operating voltage, fast switching speed, and nonvolatility. In recent years, high permittivity dielectrics have been studied intensively for ferroelectric random access memories (FRAM) owing to low operating voltage and fast switching speed and nonvolatility Bi-layered Bi/sub 4-x/La/sub x/Ti/sub 3/O/sub 12/ have been intensively studied.

A facile synthesis of Al-doped BaTiO3 thin films by a hydrothermal-galvanic couple method on TiAlN film electrodes

A status report is given on high-dielectric (usually ferroelectric) thin-films of fine-grained ceramics utilized for ferroelectric memories, including active memory elements in nonvolatile random access memories (NV-RAMs), passive capacitors in dynamic random access memories (DRAMs), and ferroelectric gates in ferroelectric field-effect transistors (FEMFETs) configured for non-destructive read-out (NDRO) memories. Emphasis is upon breakdown fields, leakage current, fatigue, and retention. Both the BaxSr1-xTiO3 (BST) family and the SrBi2Ta2O9 family of layer-structure perovskites are discussed. The review ends with a list of unsolved physics questions about ferroelectric thin films that will be helpful in further engineering developments.

The antiferroelectrics is antiparallel orientations of neighboring dipoles accompanying an antiferroelectric-ferroelectric (AFE-FE) transition under a high field. However, the ferroelectric domains are unstable and easily return to the antiferroelectric, once the external field is removed. From our works, the high-field ferroelectric phase is maintained at zero field within antiferroelectric PbZr0.96Ti0.04O3/Al2O3 stacking layers, where Al2O3 layer is conductive under the high field to permit AFE-to-FE transition but insulating immediately at zero field to block FE-to-AFE transition. This investigation implies the possibility of antiferroelectric materials for the future application of nonvolatile ferroelectric random access memories.