Effect of ferroelectric polarization on current response of PZT thin films

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In this work, we analyzed the optical degradation of 845 nm VCSELs designed for silicon photonics (SiPh) applications as a function of the oxide aperture. First, we investigated the optical degradation in relation to the stress current. The experimental results showed that devices with a larger oxide aperture exhibit better reliability. From the analysis of the degradation kinetics, we found that the current at which the highly accelerated degradation process occurs depends inversely on the aperture radius.

Lifting nanodevices from planar to three-dimensional architectures enables new functionalities by breaking symmetries and increasing device density. Two promising material classes for beyond-CMOS nanoscale technologies are superconductors and ferromagnets. Superconductors exhibit macroscopic quantum coherence, enabling dissipationless currents and making them attractive for ultrasensitive sensors and quantum computing. In ferromagnets, low-energy spin excitations, known as spin waves or magnons, propagate w

Technological advancements continuously require systems that feature higher levels of miniaturization and functional integration, from consumer electronics to medical and industrial fields. Moreover, the growing focus on sustainability more than ever demands devices that not only perform well but are also increasingly energy-efficient. At the component level, MEMS (micro-electromechanical systems) represent a particularly advantageous solution. These microsystems include structural parts that can be analyze

Centimeter-sized single crystals of Ba2LaFeNb4O15 were grown from a high-temperature solution by using LiBO2 flux and a sealed platinum assembly. The obtained single crystals display the same physical properties as their ceramic counterparts. A frequency-dependent dielectric permittivity maximum was found (Tm = 100 K at 5 kHz), which indicates relaxor behavior. Magnetic susceptibility measurements revealed purely paramagnetic behavior between 10 and 350 K. X-ray diffraction measurements of Ba2LaFeNb4O15 sin

Current low temperature electronics (175°C) for prolonged periods of time require packaging technologies that have to tackle many new problems. At high temperatures traditionally used materials such as organic circuit boards, adhesives and standard solders degrade rapidly or undergo changes in structure and pro

We report on the fabrication of a low cost sensing platform which includes printed / electroplated resistive thermometers and capacitive-based humidity sensors working at ultra low power consumption. Both types of devices were integrated on the same polymeric foil substrate. The electrodeposition of metal on the inkjetprinted lines was found to bring several advantages to the devices. For the resistors, we found a linear response of the resistance with a varying temperature range, which included environment

Intermittent convective transport caused by blobs is universally observed at the edge of laboratory plasmas and it is of great importance for future fusion reactors. We present recent advances in the basic study of blob formation and propagation dynamics and related universal properties in TORPEX simple magnetized plasmas. Blobs are generated from quasi-coherent interchange modes and, driven by ∇B and curvature-induced charge separation, propagate radially outwards. Depending on the regime, their velocity i

Single-electron bipolar avalanche transistors (SEBATs) enable current sensing by electron counting at room temperature. Here, differential SEBAT circuits combining the functions of amplification and analog-to-digital (A/D) conversion are proposed and characterized for two applications: Low-current AID conversion and differential voltage A/D conversion. Charge detection efficiencies in the order of 30% are reached, allowing for the direct A/D conversion of currents in the 10(-13) A range. An equivalent of th

High-Q, bulk acoustic wave composite resonators based on a symmetric layer sequence Of SiO2-A1N-SiO2 sandwiched between electrodes have been developed. Acoustic isolation was achieved by means of deep silicon etching to obtain membrane type TFBAR's. Three different device versions were investigated. The SiO2 film thicknesses was varied (70nm, 310mn and 770nm) while the piezoelectric A1N film had a constant thickness of 1.2 mu m. The sputter deposited A1N film grown on the amorphous, sputter deposited SiO2 l

Lead oxide based ferroelectrics, represented by lead zirconate titanate (Pb(Zr,Ti)O-3) or PZT) are the most widely used materials for piezoelectric actuators, sensors and transducers due to their excellent piezoelectric properties. Considering lead toxicity, there is interest in developing piezoelectric materials that are biocompatible and environmentally friendlier. The low density of non-lead based materials can also be an advantage in transducers for underwater and medical imaging due to expected lower a

Systems with a ferroelectric to paraelectric transition in the vicinity of room temperature are useful for devices. Adjusting the ferroelectric transition temperature (T-c) is traditionally accomplished by chemical substitution - as in BaxSr1-xTiO3, the material widely investigated for microwave devices in which the dielectric constant (epsilon(r)) at GHz frequencies is tuned by applying a quasi-static electric field(1,2). Heterogeneity associated with chemical substitution in such films, however, can broad

Strontium barium niobate thin films have been deposited by pulsed laser deposition on (111)-textured Pt films, p-doped Si(I 00) and Nb doped STO (SrTiO3) single crystals. The deposition parameters were optimized for obtaining phase pure (001)-oriented films from stochiometric targets. The samples were annealed in oxygen to improve top electrode adhesion and reduce oxygen vacancies. The SBN/substrate interfaces were investigated by means of TEM combined with EDAX chemical analysis. Growth on silicon resulted

A new test facility, dedicated to the measurement of contact resistance distribution in full-size conductor termination, has been designed and manufactured at CRPP Fusion Technology in Villigen, Switzerland. The facility will be used to characterize and qualify the ITER joints (both prototype and industrial). The basic components of the new facility are: a medium size, liquid helium cryostat to host the termination sample, a cryogenic, parallel resistor array for providing balanced current injection in up t

Three wet chemistry routes were used to synthesize Ba0.99Zr0.8Y0.2O3-delta (BZY20) and to avoid the drawbacks of the conventional mixed oxide route used for its preparation. Pure samples were prepared using the Matrix Trapping and Decomposition (MTD) and Polyacrylamide Gel (PG) processes. The compound as a powder is thermodynamically stable up to 1250 degreesC while the purity of the bulk of a pellet can be maintained up to 1500 degreesC. An expected increase of the lattice parameter (from 0.4193 (BaZrO3) t

Deposition of a hydrothermal method has a number of advantages; low deposition temperature, high-purity, deposition on a three-dimensional structure, and a large thickness. The present paper investigates the improvement of an epitaxial lead zirconate titanate (PZT) thin film deposited via hydrothermal synthesis. The critical parameter contributing to the film morphology was revealed to be the holding position of the reaction solution during deposition. In addition to this improvement, the SrRuO3 bottom elec

The influence of addition of a low-loss linear dielectric material to a tunable ferroelectric material has been investigated in terms of the electrostatic consideration. The calculations of the dielectric loss and dielectric non-linearity of ferroelectric-dielectric composites have been performed by using three different models. On the basis of results obtained, the figure of merit of the composite material has been evaluated. No improvement of the figure of merit of composite material compared to the pure

A combined thermal and simple kinetic model is applied to a small single solid oxide fuel cell (SOFC, 20 cm2 square cell of anode supported electrolyte with 1 cm2 active area). The aim was to compute the temperature field to analyze the operating conditions of the active area of the cell. The cell is simulated in the conditions used for electrochemical characterization, i.e. at negligible fuel utilization and thermally non-adiabatic. Though using a very simple kinetic model, the simulated polarization curve

Microcavity exciton polaritons, the fundamental optical excitations of semiconductor microcavities with quantum wells inside, have been proposed as promising candidates for observing stimulated scattering, condensation and other phenomena related to the bosonic nature of excitons. Having a light mass, quantum degeneracy of polaritons can be reached at low densities and high temperatures. But the radiative time of polaritons is very short (in the picosecond range) and usually prevents an efficient thermaliza

A Power-electronic interface for supercapacitive-storage based substation in DC-transportation networks is proposed, which allows to feed as a current-source in any voltage conditions of the line. The system has been designed as a compensation-substation to be placed at weak points like end-of-line stations, and can replace supplementary feeding substations. A dedicated power-electronic converter with associated control system is proposed, for the stabilization of the voltage level at the point of coupling.

The ac loss of superconducting composite depends strongly on coupling between superconducting filaments via the resistive matrix. The established technique for loss reduction using twisted filaments relies on the decoupling of the filaments below a critical coupling field Bc, which increases with the reduction of the twist pitch and the matrix conductivity. Although the concept of Bc may be clearly demonstrated using two infinite slabs of finite length, further details on its correlation with the filament/c

Effect of ferroelectric polarization on current response of PZT thin films

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