Introduction Of Additional Layer Research Articles

Improved Polarization‐Retention‐Endurance in Hf0.5Zr0.5O2 Films by ZrO2 Capping via Electrostatic Effects

AbstractFerroelectric hafnia is one of the most promising materials for next generation of non‐volatile memory devices. Several strategies have demonstrated to be of interest to improve its functional properties. Interface engineering, realized by the introduction of additional layer in the capacitor structure, is demonstrated as a promising strategy. However, interface layers can have multiple implications, such as changes in the chemistry of the interfaces and an increase of depolarization field, whose effects are difficult to discriminate. The role of HfO2 and ZrO2 capping is explored on polarization, retention, endurance, and leakage properties of Hf0.5Zr0.5O2 epitaxial films. In HfO2 capped films, lower polarization is observed, and endurance and retention are also comparably worse than in ZrO2 capped films. Complementary under illumination ferroelectric characterization and capacitance measurements indicate a reduction of defects and interface capacitance contribution in ZrO2 capped films. For both cappings, the interfaces with the Hf0.5Zr0.5O2 layer are shown to be compositionally sharp and the phase of Hf0.5Zr0.5O2 (HZO) grains is replicated on the capping layer, indicating that electrostatic effects prevail and that the use of interface layers with high permittivity, here ZrO2, is crucial to favor good functional properties.

FSS bandwidth design using miniaturized elements for angular stability in transmission

Frequency-selective surfaces (FSSs) are commonly employed at microwave frequencies in electromagnetic filtering applications. This paper reports the use of cascaded dual miniaturized elements for radio secure environments where miniaturized elements have been used creating a reduced unit cell (<0.1 wavelengths), and exceptional angular stability. Thin, flexible and optically transparent FSS samples were fabricated by laser engraving elements into a conductive aluminium layer, with a supporting Mylar substrate (relative permittivity 2.7), and thickness of 65 μm. The linearly polarized transmission response was investigated numerically by exploring the scattering parameters and the surface currents at resonance. Miniaturized elements in both single and cascaded FSS structures, have been explored to create both broadband and multiband responses across the L and S frequency bands. The theoretical and experimental results were in good agreement for the fabricated dual element dual layer translated band-stop FSS, displaying a resonant frequency reduction of 70% compared to a square loop with the same dimensions, along with significantly broad operation bandwidths of 118% and 104% for simulated and measured, respectively. These improvements were due to the selection of the individual elements in the array, their geometric arrangement, and the introduction of additional layers with lateral offsets.

DiversePathsJ: diverse shortest paths for bioimage analysis.

MotivationWe introduce a formulation for the general task of finding diverse shortest paths between two end-points. Our approach is not linked to a specific biological problem and can be applied to a large variety of images thanks to its generic implementation as a user-friendly ImageJ/Fiji plugin. It relies on the introduction of additional layers in a Viterbi path graph, which requires slight modifications to the standard Viterbi algorithm rules. This layered graph construction allows for the specification of various constraints imposing diversity between solutions.ResultsThe software allows obtaining a collection of diverse shortest paths under some user-defined constraints through a convenient and user-friendly interface. It can be used alone or be integrated into larger image analysis pipelines.Availability and implementation http://bigwww.epfl.ch/algorithms/diversepathsj Supplementary information Supplementary data are available at Bioinformatics online.

Interface-type resistive switching in perovskite materials

Resistive switching (RS) is currently one of the hot topics in the frontier between materials science and microelectronics, crosslinking both research communities. Among the different types of RS phenomena that have been reported, this review focuses particularly on interface-type RS, for which the change in resistance is related to a modification in the materials properties occurring at the interface over the entire electrode area. In particular we have summarized the most interesting reports on perovskite oxides, a versatile oxide crystal structure which presents a plethora of functional properties depending on its exact composition and structural symmetry. We present the most relevant mechanisms inducing RS, such as valence change, due to a combination of oxygen vacancy drift and redox reactions; electronic correlations; and ferroelectricity. For each case we explain the physico-chemical processes triggered by the application of an external voltage (or current), which ultimately lead to a change in resistance at the interface between the metal electrode and the oxide. Special attention is paid to the material aspects of interface-type switching, and in particular to how the RS characteristics can be improved or triggered by cation doping and oxygen off-stoichiometry, by the introduction of additional layers and by changing the nature of the electrodes. Recent progress in memristive devices based on perovskites is also reported and the figures of merit reached are compared to those obtained for state-of-the-art filamentary type RS binary oxides.