STRUCTURE DES JOINTS DE GRAINS DANS LE GERMANIUM

Des joints de flexion symétriques d'axe [011] e t [001] dans le germanium ont été étudiés par microscopie électronique conventionnelle en transmission. Une synthèse de nos principaux résultats dégage quelques caractéristiques de ces joints. Les observations expérimentales sont illustrées par l'étude du joint (1[MATH]0) Σ=5 pour lequel un modèle est proposé.Some [011] and [001] symmetrical tilt grain boundaries in germanium have been studied using conventional T E M. A synthesis of our main results points out some characteristics of these bouniaries. Experimental observations are illustrated with the study of the (1[MATH]0) Σ=5 boundary which is modeled

A two steps CVD process for the growth of silicon nano-crystals

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Strain in epitaxial Si/SiGe graded buffer structures grown on Si(100), SI(110) and SI(111) optically evaluated by polarized Raman spectroscopy and imaging.

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Reduced Pressure-Chemical Vapour Deposition of Si/SiGe heterostructures for nanoelectronics

International audienceWe have first of all quantified the impact of pressure on Si and SiGe growth kinetics. Definite growth rate and Ge concentration increases with the pressure have been evidenced at low temperatures (650–750 °C). By contrast, the high temperature (950–1050 °C) Si growth rate either increases or decreases with pressure (gaseous precursor depending). We have then described the selective epitaxial growth process we use to form Si or Si0.7Ge0.3:B raised sources and drains on ultra-thin patterned Silicon-On-Insulator (SOI) substrates. We have afterwards presented the specifics of SiGe virtual substrates and of the tensile-strained Si layers grown on top (used as templates for the elaboration of tensily strained-SOI wafers). The tensile strain, which can be tailored from 1.3 up to 3 GPa, leads to an electron mobility gain by a factor of 2 in n-Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) built on top. High Ge content SiGe virtual substrates can also be used for the elaboration of compressively strained Ge channels, with impressive hole mobility gains (×9) compared to bulk Si. After that, we have described the main structural features of thick Ge layers grown directly on Si (that can be used as donor wafers for the elaboration of GeOI wafers or as the active medium of near infrared photo-detectors). Finally, we have shown how Si/SiGe multilayers can be used for the formation of high performance 3D devices such as multi-bridge channel or nano-beam gate-all-around FETs, the SiGe sacrificial layers being removed thanks to plasma dry etching, wet etching or in situ gaseous HCl etching

Impact of the pre amorphization by Ge implantation on Ni0.9_{0.9}Pt0.1_{0.1} silicide

International audienceThe impact of the Pre Amorphization by Ge Implantation (PAI) on Ni0.9Pt0.1 silicide is studied. Reactions between a 10 nm thick Ni0.9Pt0.1 film and Si (100) substrate are analyzed as a function of the induced amorphous-Si thicknesses. In view of being compatible with the integration constraint of the 28 nm CMOS technologies, the Ge implantation dose is fixed at a low level. The relative position of the amorphous-Si/crystalline-Si interface and the silicide growth front is defined for each sample. Then, in-situ XRD analyses, X-Ray Reflectometry (XRR) and Sheet resistance (Rs) measurements are achieved to provide a deep study of silicide growth kinetics and silicide properties. First, a clear relationship is established between the silicide growth rate and the amorphous-Si thickness. Secondly, an easier NiSi nucleation and a decrease of its resistivity is observed when NiSi nucleates at the θ-Ni2Si/a-Si interface. These observations are discussed considering the impact of the amorphous-Si layer on the driving force, the nucleation barrier, the lateral growth rate, and NiSi roughness

Investigation of charge-trap memories with AlN based band engineered storage layers

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Potentialities of LiTaO3 for Bulk Acoustic Wave Filters

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Infection and mortality of healthcare workers worldwide from COVID-19:A systematic review

Objectives To estimate COVID-19 infections and deaths in healthcare workers (HCWs) from a global perspective during the early phases of the pandemic. Design Systematic review. Methods Two parallel searches of academic bibliographic databases and grey literature were undertaken until 8 May 2020. Governments were also contacted for further information where possible. There were no restrictions on language, information sources used, publication status and types of sources of evidence. The AACODS checklist or the National Institutes of Health study quality assessment tools were used to appraise each source of evidence. Outcome measures Publication characteristics, country-specific data points, COVID-19-specific data, demographics of affected HCWs and public health measures employed. Results A total of 152 888 infections and 1413 deaths were reported. Infections were mainly in women (71.6%, n=14 058) and nurses (38.6%, n=10 706), but deaths were mainly in men (70.8%, n=550) and doctors (51.4%, n=525). Limited data suggested that general practitioners and mental health nurses were the highest risk specialities for deaths. There were 37.2 deaths reported per 100 infections for HCWs aged over 70 years. Europe had the highest absolute numbers of reported infections (119 628) and deaths (712), but the Eastern Mediterranean region had the highest number of reported deaths per 100 infections (5.7). Conclusions COVID-19 infections and deaths among HCWs follow that of the general population around the world. The reasons for gender and specialty differences require further exploration, as do the low rates reported in Africa and India. Although physicians working in certain specialities may be considered high risk due to exposure to oronasal secretions, the risk to other specialities must not be underestimated. Elderly HCWs may require assigning to less risky settings such as telemedicine or administrative positions. Our pragmatic approach provides general trends, and highlights the need for universal guidelines for testing and reporting of infections in HCWs. © Author(s) (or their employer(s)) 2020