Transport property study of MgO-GaAs(001) contacts for spin injection devices

International audienceThe electrical properties of Au/MgO/n-GaAs(001) tunnel structures have been investigated with capacitance-voltage and current-voltage measurements at room temperature with various MgO thicknesses between 0.5 and 6.0nm. For an oxide thickness higher than 2nm and for low bias voltages, the voltage essentially drops across the oxide and the structure progressively enters the high-current mode of operation with increasing reverse bias voltage, the property sought in spin injection devices. In this mode, we demonstrate that a large amount of charge accumulates at the MgO/GaAsinterface in interface traps located in the semiconductor band gap

Vers un rapprochement de l'IDM et de la compilation

National audienceL'ingénierie dirigée par les modèles (IDM) s'intéresse à la définition de systèmes complexes par leur représentation et leur abstraction à l'aide de langages de modélisation dédiés à un domaine. Le domaine de la compilation s'intéresse quant à lui à des analyses et à des traitements complexes sur des structures de données (depuis les analyses lexicale et syntaxique jusqu'à l'optimisation par rapport à la cible d'exécution). Motivées par des objectifs initiaux différents, ces deux communautés ont longtemps mené des travaux qui apparaissent aujourd'hui comme complémentaires et qui convergent vers le domaine de l'" ingénierie des langages ". Ce domaine aborde toutes les phases du cycle de vie d'un langage, depuis sa définition jusqu'à son usage. Pour cela elle regroupe des besoins en terme de développement et d'outillage des langages. Dans cet article nous analysons les apports de l'IDM et de la compilation à l'ingénierie des langages. Nous dressons ensuite un panorama des verrous à lever pour permettre une fertilisation croisée de ces deux communautés

Bridging the Chasm Between MDE and the World of Compilation

International audienceModeling and transforming have always been the cornerstones of software system development, albeit often investigated by different research communities. Modeling addresses how information is represented and processed, while transformation cares about what the results of processing this information are. To address the growing complexity of software systems, Model-Driven Engineering (MDE) leverages Domain Specific Languages (DSL) to define abstract models of systems and automated methods to process them. Meanwhile, compiler technology mostly concentrates on advanced techniques and tools for program transformation. For this, it has developed complex analyses and transformations (from lexical and syntaxic to semantic analyses, down to platform-specific optimizations). These two communities appear today quite complementary and are starting to meet again in the Software Language Engineering (SLE) field. SLE addresses all the stages of a software language lifecycle, from its definition to its tooling. In this article, we show how SLE can lean on the expertise of both MDE and compiler research communities and how each community can bring its solutions to the other one. We then draw a picture of the current state of SLE, and of the challenges it has still to face

In-plane magnetic anisotropies in epitaxial Fe(001) thin films

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Tuning the Schottky barrier height at MgO/metal interface

International audienceWe present an experimental investigation of the interface electronic structure of thin MgO films epitaxially grown on Ag(001) by x-ray and ultraviolet photoemission spectroscopy as a function of the oxide growth conditions. It is shown that the Schottky barrier height at MgO/metal interface can be tuned over 0.7 eV by a modification of the oxygen partial pressure or the sample temperature. These experimental results are explained in the framework of the extended Schottky-Mott model and the MgO-induced polarization effect by Mg enrichment of the silver surface region

Work function shifts, Schottky barrier height, and ionization potential determination of thin MgO films on Ag(001)

International audienceThe electronic band structure and the work function of MgO thin films epitaxially grown on Ag(001) have been investigated using x-ray and ultraviolet photoelectron spectroscopy for various oxide thicknesses. The deposition of thin MgO films on Ag(001) induces a strong diminution in the metal work function. The p-type Schottky barrier height is constant at 3.85+/-0.10 eV above two MgO monolayers and the experimental value of the ionization potential is 7.15+/-0.15 eV. Our results are well consistent with the description of the Schottky barrier height in terms of the Schottky-Mott model corrected by an MgO-induced polarization effect