The role of C and N dopants incorporation in phase change materials

Phase change memory (PCM) technology is considered to be among the most promising alternatives to conventional technologies in embedded memories [1]. To allow operation at relatively high temperatures in embedded applications, it is crucial to improve the stability of the amorphous phase. Carbon and nitrogen doping have been shown to significantly increase the crystallization temperature [1-3]. Moreover, the high RESET current requirement [2], which is a limit to the scalability of GeTe and GST, can be reduced by the incorporation of a dopant element [4]. In this presentation we focus on correlating experimental results and ab initio simulations to understand the effect of C and N incorporation in GeTe and GST PCM devices. Understanding the effect of dopants on the change of electronic properties and the mechanisms of the phase transformation requires analysis of the local order and structure of the amorphous to crystalline phases. In this context, we demonstrate that carbon and nitrogen deeply affects the structure and the dynamical properties of the amorphous phase of GeTe. In particular, the inclusion of N and C dopant elements in GeTe has a drastic effect on the vibrational modes of GeTe therefore improving the stability of the glass. This effect goes with an increased mechanical rigidity explaining why these doped GeTe compounds have a higher crystallization temperature than the undoped ones. Finally we will explore, mainly by FTIR and XRD measurements, the effect of C and N dopants during the annealing of amorphous PCMaterials towards their crystalline phases. These results will be discussed in order to understand the origin of the differences of the doped PCMaterials amorphous phase stability (data retention) observed between full sheet materials and the materials integrated in PCM devices. [1] A. Fantini et al., 2010 IEEE International Electron Devices Meeting (IEDM), 2010, pp. 29.21.21-29.21.24. [2] G. Betti Beneventi et al., Solid-State Electronics, 65-66 (2011) 197-204. [3] V. Sousa et al., EPCOS 2011. [4] Q. Hubert et al., IMW 2012.A.R.C. Themoter

Approches actuelles en analyse environnementale des micropolluants organiques

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Outcome of exudative aged-related macular degeneration (ARMD) after 3 intravitreal injections of bevacizumab

Purpose: To evaluate the efficacy of intravitreal injections of bevacizumab in exudative ARMD. Methods: Retrospective study including naive patients suffering from exudative ARMD whatever the type of neovascularisation. All the participants were treated with three monthly 1.25 mg intravitreal injections of bevacizumab.The primary objective was far and near visual acuity (VA) 1, 3 and 6 months after the third injection. The secondary objective was the residual activity of neovascularisation assessed with fluorescein and ICG angiography and retinal thickness evaluated with OCT3. Results 71 eyes of 66 patients were included. Neovascularisation was occult, visible or combined in 65%, 20% and 15% of the cases, respectively. A statistically significant improvement between pre and post‐injection VA (LogMAR) was observed one month after the third injection, 0.88±0.57 and 0.77±0.60, respectively, p=0.001). An active neovascularisation was still present at that time in 57.7% of the eyes and 34% at 6 months needing further bevacizumab injections (3.85±0.96 per eye). VA was similar at 1, 3 and 6 months (F71,2=1,54 ; p=0,46). A complication occurred in 3 eyes. Conclusion: Three bevacizumab intravitreal injections led to a significant VA improvement. However, more than half of the eyes had an active neovascularisation after these 3 injections

L’atelier de lecture, Cm 1 - cycle 3, Cahier d’entraînement

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L’atelier de lecture, Cm 1 - cycle 3, Cahier d’entraînement

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Enantiomeric fractionation of metoprolol and its major transformation products for quantitative biodegradation measurement and elucidation of biodegradation mechanisms

International audienceEnantiomeric fractionation of metoprolol and its major transformation products for quantitative biodegradation measurement and elucidation of biodegradation mechanism

Chemical state of Ag in Conducting Bridge Random Access Memory cells: a depth resolved X-ray Absorption Spectroscopy investigation

International audienceConducting Bridge Random Access Memories (CBRAM) are a promising substitute for FLASH technology but problems with limited retention of the low resistance ON state still hamper their massive deployment. Depth resolved X-ray Absorption Spectroscopy has been used to describe the chemical state of the atoms of the active electrode (in this case Ag) and to reveal the role of Sb as stabilizer of the metallic stat