Ge2Sb2Te5 layer used as solid electrolyte in conductive-bridge memory devices fabricated on flexible substrate

7 pagesInternational audienceThis paper shows that the well-know chalcogenide Ge2Sb2Te5 (GST) in its amorphous state may be advantageously used as solid electrolyte material to fabricate Conductive-Bridge Random Access Memory (CBRAM) devices. GST layer was sputtered on preliminary inkjet-printed silver lines acting as active electrode on either silicon or plastic substrates. Whatever the substrate, the resistance switching is unambiguously attested at a nanoscale by means of conductive-atomic force microscopy (C-AFM) using a Pt-Ir coated tip on the GST surface acting as a passive electrode. The resistance change is correlated to the appearance or disappearance of concomitant hillocks and current spots at the surface of the GST layer. This feature is attributed to the formation/dissolution of a silver-rich protrusion beneath the AFM tip during set/reset operation. Beside, this paper constitutes a step toward the elaboration of crossbar memory arrays on flexible substrates since CBRAM operations were demonstrated on W/GST/Ag crossbar memory cells obtained from an heterogeneous fabrication process combining physical deposition and inkjet-printing

Fabrication and characterization of ECM memories based on a Ge2Sb2Te5 solid electrolyte

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Directional solidification of refined Al–3.5wt% Ni under natural convection and under a forced flow driven by a travelling magnetic field

International audienceA new Bridgman-type furnace has been designed and built.This furnace has two specific items: a device conceived to minimise any residual radial thermal gradient near the solid–liquid interface (induced by the difference in thermal conductivities between liquid and solid), and a travelling magnetic field to drive a forced flow in the liquid above the solidifying interface. We have already performed comparative experiments of directional solidification on refined and non-refined Al-based alloys, under natural convection and under forced flow, controlled by the travelling magnetic field. We will present some characteristics of this new furnace, and the preliminary results obtained by solidifying refined Al–3.5 wt% Ni, with and without the travelling magnetic field

Effect of Travelling Magnetic Field on the Directional Solidification of refined Al-3.5 wt %Ni alloys

The specific objective of the paper is to investigate the effect of fluid flow on the development of a dendritic microstructure and more particularly on the columnar and equiaxed solidification regimes. A gradient furnace (BATMAF) with a possibility of applying a travelling magnetic field was designed for the solidification of aluminium-based alloys. The travelling magnetic field (TMF) drives a forced flow in the liquid above the solidifying interface. Some experiments are achieved in this furnace on an Al-Ni3.5wt% refined alloy. As a result, a significant change of the microstructure due to the transversal melt flow is observed. This work is performed in the framework of the CETSOL/MICAST Microgravity Application Projects of the European Space Agency (ESA)

Stress buildup during crystallization of thin chalcogenide films for memory applications: In situ combination of synchrotron X-Ray diffraction and wafer curvature measurements

Symposium DD on Current Trends in Optical and X-Ray Metrology of Advanced Materials for Nanoscale Devices IV, Lille, FRANCE, MAY 11-15, 2015International audiencePhase change materials (PCMs) such as Ge2Sb2Te5 (GST) undergo a reversible amorphous-to-crystal transition that is the basis of their interest for next generation non-volatile memories. The large density change upon crystallization raises important issues because of the large mechanical stresses occurring during memory cycling. In order to investigate the intimate relationship between stress buildup and microstructure evolution we have built a dedicated setup, which allows combining X-ray diffraction and curvature measurements on DiffAbs beamline at SOLEIL synchrotron. Using a thin (30 nm) GST film deposited on Si we show that this setup yields a wealth of interesting results. A clear correlation is observed between phase transition and stress buildup. Detailed information is obtained on the thermomechanical behavior of the different phases. Systematic investigation of PCMs with this original setup will help understanding the thermomechanical behavior of PCM thin films and nanostructures. (C) 2016 Elsevier B.V. All rights reserved