Ferroelectric Pb ZrxTi1 Research Articles

Enhanced Photoresponse in GeSe‐Based Phototransistors by Ferroelectric Gating

GeSe, a black phosphorus analogue, has great potential in the applications of optoelectronic devices due to its distinct optical properties and air stability. Developing techniques that can boost the photoresponsivity of GeSe‐based photodetectors is essential to promoting their practical applications. Herein, ferroelectric PbZrxTi1−xO3 (PZT) gating is introduced as an effective method to enhance the performance of GeSe‐based transistors. Comparative study on the performance of conventional Si/SiO2‐ and PZT‐gated GeSe phototransistors demonstrates a 3.1 times increase in photoresponsivity under zero gate voltage by ferroelectric gating. Furthermore, the PZT‐gated photodetector shows a rise time of 52 ms and a maximal external quantum efficiency (EQE) of 45% across the visible and near‐infrared range. These results indicate that ferroelectric gating is a promising methodology to enhance the performance of GeSe‐based photodetectors. This work paves a new pathway toward developing high‐performance photodetectors.

Interfacing Plasmonic Nanoparticles with Ferroelectrics for Hot-Carrier-Driven Photocatalysis: Impact of Schottky Barrier Height

Emergent strategies for efficient solar energy conversion have focused on ways to harness photons in the lower-energy range of sunlight that cannot be utilized by conventional semiconductor photocatalyst systems. Recent research has demonstrated that interfaced plasmonic–ferroelectric particles represent a promising strategy for the utilization of near-infrared (NIR) light owing to the possibility of the more efficient injection of hot charge carriers from noble metal nanoparticles. Described herein, platinum-end-capped gold nanorods (AuNRs) function as antennae to absorb low-energy NIR photons to generate hot electrons that can be injected into ferroelectric PbZrxTi1–xO3 (PZT; x = 0.48, 0.50, 0.52, 0.54, 0.56, and 0.60) and drive the reduction of water to molecular hydrogen at its surfaces. As an aqueous suspension, the interfaced AuNR-PZT particles exhibited maximal photocatalytic rates for hydrogen formation under a 976 nm diode laser (powder density = 2.0 W cm–2) for the 52% Zr (x = 0.52) composition ...

Multiferroic PbZrxTi1−xO3/Fe3O4 epitaxial sub-micron sized structures

Large range well ordered epitaxial ferrimagnetic nominally Fe3O4 structures were fabricated by pulsed-laser deposition and embedded in ferroelectric PbZrxTi1−xO3 (x = 0.2, 0.52) epitaxial films. Magnetite dots were investigated by magnetic force microscopy and exhibited magnetic domain contrast at room temperature (RT). Embedding ferroelectric PbZrxTi1−xO3 layers exhibit remnant polarization values close to the values of single epitaxial layers. Transmission electron microscopy demonstrated the epitaxial growth of the composites and the formation of the ferrimagnetic and ferroelectric phases. Physical and structural properties of these composites recommend them for investigations of stress mediated magneto-electric coupling at room temperature.

Interfacial strain effects in epitaxial multiferroic heterostructures of PbZrxTi1−xO3∕La0.7Sr0.3MnO3 grown by pulsed-laser deposition

Ferroelectric PbZrxTi1−xO3 and ferromagnetic La0.7Sr0.3MnO3 films were grown on SrTiO3(100) substrates in order to fabricate multiferroic epitaxial heterostructures. Multilayers of PbZr0.2Ti0.8O3∕La0.7Sr0.3MnO3 with 5nm thin individual layers preserve good magnetic properties and have a transition temperature of ∼320K. The variation of the magnetic coercive field of thin La0.7Sr0.3MnO3 films, sandwiched between PbZrxTi1−xO3 films of increasing Zr content in the same epitaxial heterostructure, demonstrates the influence of the interfacial biaxial strain.

Fabrication of ferroelectric PbZrxTi1−xO3 thick films and their optical waveguide properties

3 μm thick ferroelectric PbZrxTi1−xO3 films with x=0.4 and 0.5 have been fabricated on LaNiO3 coated silicon substrates by a modified sol-gel process. X-ray diffraction analysis shows that the films exhibit highly (100)-preferred orientation (α100>99%) and a single perovskite phase. Atomic force microscopy study shows that specimens possess smooth surfaces. The prism-film coupling measurement indicates that the system with the configuration of PbZr0.5Ti0.5O3/PbZr0.4Ti0.6O3/air can be used for a planar optical waveguide.

Growth and characterization of epitaxial ferroelectric PbZrxTi1−xO3 thin film capacitors with SrRuO3 electrodes for non-volatile memory applications

Non-volatile FeRAMs based on thin film ferroelectric capacitors are emerging as an advantageous replacement for EEPROM and flash devices. In this work, ferroelectric Al/PbZrxTi1−xO3 (PZT)/SrRuO3 thin film capacitors were fabricated and its suitability for memory applications was tested. The PZT films, as well as the SrRuO3 bottom electrodes have been grown by pulsed laser deposition on LaAlO3(001) substrates. Epitaxial heterostructures with high crystalline quality were obtained. Top aluminum electrodes were thermally evaporated onto the PZT films. High dielectric constant of 700 and dielectric loss tangent of 0.03 were obtained. Good ferroelectric behavior with an activation field for switching γ=308 kV/cm and a low coercive voltage of 1.1 V at 40 Hz was observed. The reliability of the thin film capacitors has been tested by means of pulse switching measurements. The polarization shows very little fatigue with cumulative switching. Built-in imprint, arising from the use of asymmetric electrodes, along with induced imprint related to charge trapping at the interfaces were observed.

Determination of Ir consumption during thermal oxidation and PbZrxTi1−xO3 processing using Bragg-peak fringe analysis

Thickness interference fringes can be seen around the Bragg peaks of a variety of polycrystalline thin (10–20 nm) films using standard x-ray diffraction techniques in a conventional Bragg–Brentano geometry. In this article, thickness fringe analysis is used to investigate oxidation and roughening in thin Ir films with and without overlayers of the ferroelectric PbZrxTi1−xO3 (PZT). Changes in fringe spacing were used to determine the Ir thickness consumed by oxidation. Fringe contrast degradation (indicating roughening) was observed both after oxidation anneals (which formed a surface layer of IrO2) and after subsequent reduction anneals (which converted the IrO2 back to Ir). Film overlayers were found to have a protective effect against oxidation and roughening, as evidenced by comparison of postoxidation fringe patterns for bare and PZT-coated Ir films. Overall, our results demonstrate that thickness fringe analysis can be used as a simple, quantitative probe of processing-induced thin film thickness and morphology changes.

Epitaxial ferroelectric PbZrxTi1–xO3 thin films for non-volatile memory applications

Epitaxial ferroelectric PbZrxTi1–xO3 (PZT) thin film capacitors with SrRuO3 (SRO) bottom electrodes have been fabricated by pulsed laser deposition on LaAlO3 (001) substrates. X-ray diffraction measurements revealed that epitaxial heterostructures with a high crystalline quality were obtained. Ferroelectric capacitors were defined by thermal evaporation of aluminium contact pads onto the PZT films. Remnant polarizations of about 13 μC/cm2 and coercive fields of about 150 kV/cm are obtained at a frequency of 10 Hz. The capacitors show very little fatigue of the remnant polarization with cumulative switching. A tendency to imprint, arising from the use of asymmetric electrodes, is observed.

Transient behavior and memory effect of a PbZrxTi1−xO3/YBa2Cu3O7−x three-terminal device

The transient behavior of a ferroelectric PbZrxTi1−xO3 and superconducting YBa2Cu3O7−x three-terminal device has been investigated. Four-state behavior, that is, two polarization states of the PbZrxTi1−xO3 gate and superconducting and normal states of the YBa2Cu3O7−x layer, has been observed. It was shown that the biased superconducting channel can be switched from superconducting state to the normal state by the flowing charge during the polarization switching of the PbZrxTi1−xO3 gate. The nonvolatility of this device based on the different polarization states of the ferroelectric gate has also been demonstrated.

Micro‐Raman spectroscopy of sol–gel‐derived Pb(ZrxTi1 − x)O3 thin films

AbstractThin films of ferroelectric PbZrxTi1 − xO3 were prepared by the sol–gel technique on sapphire and fused‐quartz substrates with thicknesses ranging from 0.6 to 1.2 μm. Powders of the above substance were also prepared by hydrolysis and condensation of the same precursor sol and crystallized by holding them at 600°C for either 6 or 12 h. From a comparison of the Raman spectra it is obvious that both powders and the film on sapphire substrate belong to the perovskite structure, whereas the film on fused quartz has a phyrochlore structure. These observations agree well with x‐ray measurements of diffraction patterns. Absence of 70 cm−1 E(TO) band in the film suggests that the film is rhombohedral with x being well above 0.535.