Search results for "IDE"
showing 10 items of 55536 documents
Spark Plasma Sintering à partir de poudres mécaniquement activées : compréhension des transitions de phase au cours d'un frittage réactif
2007
International audience; À " basse température " (entre 400 et 600 ◦C), l'oxydation de MoSi2 entraîne sa désintégration en poudre (phénomène de " peste "). De récents travaux ont montré que l'utilisation de MoSi2 dense et nano-organisé permettrait de ralentir ce phénomène de " peste ". Le défi de produire des matériaux denses et nano-organisés peut être relevé par le frittage " flash " réactif sous champ électrique à partir des poudres mécaniquement activées (Mechanically-Activated Spark Plasma Sintering, MASPS). Le contrôle de la composition et de la microstructure du composé intermétallique MoSi2 nécessite de déterminer les paramètres du frittage SPS (température, rampe de montée en tempér…
SIC based solid state protections switches for space applications
2017
Development and technology maturation of Silicon Carbide (SiC) power transistors over the last 15 years has motivated its study in aerospace systems. When compared with Si devices, superior voltage blocking capacity and the capability of operation at higher temperatures, give important advantages in space power electronics applications, similar to what happens in terrestrial electronics. This paper discusses the use of SiC power transistors for Solid State Power Switches especially addressed to the space segment. Two applications will be covered, the first is the Solid State Shunt Switch, widely used in high power Direct Energy Transfer (DET) photovoltaic power regulators and the second is …
Parasitic Bipolar Action in SiC Power MOSFETs Demonstrated by Two-Photon Laser Experiment
2018
A two-photon absorption technique is explored for Silicon carbide power MOSFETs and power junction barrier Schottky diodes using a pulsed laser. The similarities in design between the specific MOSFETs and diodes tested permit using mechanisms existing in the different structures as explanation for observed current variation with laser position. The diode shows variation in average current with change in laser depth only, whereas the MOSFET shows variation both with shifts in depth and shifts in position across the striped geometry of the device. The variation is explained to be due to bipolar amplification of the charge carriers generated in the MOSFET when a pulse focus includes a channel …
Electrical transport in lead-free (Na0.5Bi0.5)1–xSrxTiO3 ceramics (x = 0, 0.01 and 0.02)
2017
Lead-free (Na0.5Bi0.5)1xSrxTiO3 (x = 0, 0.01 and 0.02) ceramics were manufactured through a solid-state mixed oxide method and their ac (σac) and dc (σdc) electric conductivity were studied. It is ...
Ab Initio Modeling of Y and O Solute Atom Interaction in Small Clusters within the bcc Iron Lattice
2018
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euroatom research and training programme 2014–2018 under grant agreement No 633053. The authors are indebted to A. Möslang and P. V. Vladimirov for stimulating discussions. The views and opinions expressed herein do not necessarily reflect those of the European Commission.
The effects of thermal treatment on structural, morphological and optical properties of electrochemically deposited Bi2S3 thin films
2017
Abstract Thin films of bismuth sulfide (Bi 2 S 3 ) have been electrochemically deposited on indium–doped tin oxide substrates from aqueous solutions of Bi(NO 3 ) 3 , ethylene diamine tetraacetic acid (EDTA) and Na 2 S 2 O 3 . The structural properties of the films were characterized using X–ray diffraction and high–resolution transmission electron microscopy analyses. The film crystallizes in an orthorhombic structure of Bi 2 S 3 along with metallic bismuth. Thermal annealing of the prepared film in sulfur atmosphere improves its crystallinity and cohesion. The band gap values of the deposited film before and after annealing at 400 °C were found to be 1.28 and 1.33 eV, respectively.
Ultra-Wide Band Gap in Two-Dimensional Phononic Crystal with Combined Convex and Concave Holes
2017
A phononic crystal with an ultra‐wide band gap is proposed, whose unit cell consists of a cross‐like concave hole in the center and four square convex holes at the corners. The dispersion relations, modal kinetic energy ratio, and eigenmodes at edges of the band gaps are investigated by using the finite element method. The influence of the geometrical parameters of the convex and concave holes on the band gaps is further analyzed. After optimization, an ultra‐wide band gap with gap‐to‐midgap ratio of 156.0% is achieved, with the filling fraction keeping a relative small value. Numerical results illustrate that the combination of convex and concave holes is a practicable direction for struct…
Quasi-antiferromagnetic multilayer stacks with 90 degree coupling mediated by thin Fe oxide spacers
2019
We fabricated quasiantiferromagnetic (quasi-AFM) layers with alternating antiparallel magnetization in the neighboring domains via 90° magnetic coupling through an Fe-O layer. We investigated the magnetic properties and the relationship between the magnetic domain size and the 90° magnetic coupling via experiments and calculations. Two types of samples with a Ru buffer and a (Ni80Fe20)Cr40 buffer were prepared, and we found that with the NiFeCr buffer, the sample has a flatter Fe-O layer, leading to stronger 90° magnetic coupling and a smaller domain size compared with the Ru buffer sample. This trend is well explained by the bilinear and biquadratic coupling coefficients, A12 and B12, in L…
Barrier inhomogeneity in vertical Schottky diodes on free standing gallium nitride
2019
Abstract In this paper, the electrical behavior of a Ni/Au Schottky barrier on free standing GaN has been studied employing a variety of techniques and correlated with the material and interface quality. The temperature dependence of the ideality factor (n) and of the Schottky barrier height (ΦB) revealed a spatial inhomogeneity of the barrier. This behavior has been described by means of the Tung's model on inhomogeneous Schottky barriers. The origin of the barrier inhomogeneity can be likely associated to the surface quality of the GaN epilayer or to microstructure of the Ni/GaN interface.
High temperature oxidation of Mg2(Si-Sn)
2016
Abstract High temperature oxidation of Mg 2 Si 1- x Sn x alloys ( x = 0.1 ⿿ 0.6) has been investigated. The oxidation rate was slow for temperatures below 430 °C. In the temperature range between 430⿿500 °C all the alloys exhibited breakaway oxidation. The onset temperature of the breakaway region in general decreased with increasing level of Sn in the alloy. The breakaway behavior is explained by a combination of the formation of a non-protective MgO layer and the formation of Sn-rich liquid at the interface between the oxide and Mg depleted Mg 2 Sn.