Fabrication Of Ferroelectric Thin Films Research Articles

A BaTiO3-based flexible ferroelectric capacitor for non-volatile memories

BaTiO3 (BTO) ferroelectric films, which are renowned for their lead-free compositions, superior stability, and absence of a wake-up effect, are promising candidate materials in the field of non-volatile memories. However, the prerequisites for high-temperature conditions in the fabrication of ferroelectric thin films impose constraints on the substrate choice, which has limited the advancement in non-volatile memories based on single-crystal flexible BTO films with robust ferroelectric properties. Herein, a technique has been developed for the fabrication of flexible devices using a pulsed laser deposition system. BTO ferroelectric films have then been deposited onto a flexible mica substrate, with SrTiO3 (STO) serving as a buffer layer. The obtained flexible BTO devices exhibited excellent ferroelectricity, with a maximum polarization (2Pmax) of up to 42.58 μC/cm2 and a remnant polarization (2Pr) of up to 21.39 μC/cm2. Furthermore, even after 1000 bending cycles, the bipolar switching endurance remained high at 1012 cycles. After 104 s, the flexible BTO device still maintained excellent polarization characteristics. These results make the flexible BTO ferroelectric thin film a potential candidate for the next generation of non-volatile memories.

Subtractive fabrication of ferroelectric thin films with precisely controlled thickness

The ability to control thin-film growth has led to advances in our understanding of fundamental physics as well as to the emergence of novel technologies. However, common thin-film growth techniques introduce a number of limitations related to the concentration of defects on film interfaces and surfaces that limit the scope of systems that can be produced and studied experimentally. Here, we developed an ion-beam based subtractive fabrication process that enables creation and modification of thin films with pre-defined thicknesses. To accomplish this we transformed a multimodal imaging platform that combines time-of-flight secondary ion mass spectrometry with atomic force microscopy to a unique fabrication tool that allows for precise sputtering of the nanometer-thin layers of material. To demonstrate fabrication of thin-films with in situ feedback and control on film thickness and functionality we systematically studied thickness dependence of ferroelectric switching of lead-zirconate-titanate, within a single epitaxial film. Our results demonstrate that through a subtractive film fabrication process we can control the piezoelectric response as a function of film thickness as well as improve on the overall piezoelectric response versus an untreated film.

Low-Temperature Hydrothermal Deposition of (BaxSr1−x)TiO3 Thin Films on Flexible Polymeric Substrates for Embedded Applications

The fabrication of ferroelectric thin films on flexible metal foils or polymeric substrates is of particular interest for embedded capacitors integrated into Printed Circuit Boards (PCB). In this work, BaxSr1−xTiO3 (x = 1, 0.9, 0.7, 05, 0.3, 0.1, and 0) polycrystalline thin films were fabricated at low temperature (120 °C) and for a short time (1 h) by a hydrothermal process on commercial flexible polymeric Kapton films. Microstructural analysis showed that dense BaTiO3 thin films comparable to those derived from long time hydrothermal processes were achieved with the present synthesis conditions. With increasing strontium content, BaxSr1−xTiO3 film thickness decreased and grain size increased. For x = 0, i.e., SrTiO3, the films displayed a monolayer of coarse grains. The variation of the film morphology with the composition suggests a faster nucleation and reaction kinetics for BaTiO3 than SrTiO3. Electrical characterization showed high capacitance densities and acceptable dielectric loss for the films a...

Fabrication of Ferroelectric Thin Films With Alternate Deposition of Multilayers

Pb(Zr0.52Ti0.48)O3 (PZT) and SrBi2Ta2O9 (SBT) films have been fabricated onto Pt/Ti/SiO2/Si substrates with a new chemical solution deposition (CSD) technique, in which PbZrO3(PZ)/PbTiO3(PT) and SrTa2O6(ST)/Bi2O3(B) precursors were spin-coated and heated individually. Polycrystalline PZT and SBT films were formed through the reactions between the multilayers at relative low temperatures, without post-annealing. With the aid of AFM, an island-column hybrid growth mode and a nucleus growth mode were suggested for the PZT and SBT film growths, respectively. However, it was found that the deposition orders affected substantially the microstructure of SBT films. This study suggests that the processing temperatures for the ferroelectric film fabrications can be reduced with alternate deposition of multilayers.

Effect of Rapid Thermal Processing on the Crystallization Properties of PbTiO3 Ferroelectric Thin Film

AbstractThe fabrication methods of ferroelectric (FE) thin films have received special attention in recent years because of the needs of FE thin films integrated with semiconductor devices. Rapid thermal processing (RTP) has developed in fabrication of FE thin films because it can reduce processing temperature and time duration, and it also improves the properties of FE thin films compatible with semiconductor devices. The thin film samples used were prepared by a multi-ion-beam reactive cosputtering system (MIBRECS) at room temperature. The samples were then subjected to a post-deposition annealing in a RTP system. It was found that PbTiO3 (PT) thin film could grow on amorphous or polycrystal interfacial layer and the PT thin films annealed by RTP showed the prefered [110] and [100] textures. The effect of interfacial layer on the crystallization and microstructure of the films was also discussed.