LIFECYCLE MANAGEMENT, MONITORING AND ASSESSMENT FOR SAFE LARGE-SCALE INFRASTRUCTURES: CHALLENGES AND NEEDS

Many European infrastructures dating back to ’50 and ’60 of the last century like bridges and viaducts are approaching the end of their design lifetime. In most European countries costs related to maintenance of infrastructures reach a quite high percentage of the construction budget and additional costs in terms of traffic delay are due to downtime related to the inspection and maintenance interventions. In the last 30 years, the rate of deterioration of these infrastructures has increased due to increased traffic loads, climate change related events and man-made hazards. A sustainable approach to infrastructures management over their lifecycle plays a key role in reducing the impact of mobility on safety (over 50 000 fatalities in EU per year) and the impact of greenhouse gases emission related to fossil fuels. The events related to the recent collapse of the Morandi bridge in Italy tragically highlighted the sheer need to improve resilience of aging transport infrastructures, in order to increase the safety for people and goods and to reduce losses of functionality and the related consequences. In this focus Structural Health Monitoring (SHM) is one of the key strategies with a great potential to provide a new approach to performance assessment and maintenance over the life cycle for an efficient, safe, resilient and sustainable management of the infrastructures. In this paper research efforts, needs and challenges in terms of performance monitoring, assessment and standardization are described and discussed.The networking support of COST Action TU1402 on ‘Quantifying the Value of Structural Health Monitoring’ and of COST Action TU1406 on ‘Quality specifications for roadway bridges, standardization at a European level (BridgeSpec)

Experimental validation of the “FLoating Island” concept: realization of low on-resistance FLYMOS™ transistors

The present 14 volts automotive electrical system will soon become 42 volts. For these future automotive applications, development of 80 volts power MOSFETs exhibiting low on-resistance is desired. The “FLoating Island” MOSFET (FLIMOSFET) is one of the new candidates to break the silicon limit, which is the “specific on-resistance/breakdown voltage” trade-off limit of conventional power MOSFETs. In this paper, the “FLoating Island” concept has been implemented on silicon: new vertical N-channel FLIMOSFETs (FLYMOS™) dedicated to automotive applications (below 100 volts) have been fabricated for the first time, using two steps epitaxy process. Experimental results show that the FLYMOS™ transistor exhibit a breakdown voltage of 73 volts but also an improved specific on-resistance compared to conventional VDMOSFETs (33% reduction of the specific on-resistance for the same breakdown voltage). In other words, in terms of “specific on-resistance/breakdown voltage” trade-off, the FLYMOS™ transistor is one of the best MOS devices in low voltage applications. These measurements validate the “FLoating Island” concept and the efficiency of the original edge cell that is used in the FLYMOS™ technology

Contribution to Silicon-Carbide-MESFET ESD robustness analysis

International audienceIn this work, ElectroStatic Discharge (ESD) tests are performed on SiC MESFETs in order to understand their physical behavior and failure mechanisms during such stresses. The purpose is to point out advantages and drawbacks of this technology, paying special attention to aspects related to its possible commercialization and reliability. Three MESFETs designed to be integrated as a driver in monlithic SiC systems, featuring some ESD internal protection are investigated. Different configurations on ohmic and Schottky contacts are analyzed. Lock-in thermography is carried out for the physical failure location. With TCAD Sentaurus simulation, it allows to determine the nature of the defects on the damaged areas. Hypothesis on the failure mechanism as SiO 2 breakdown or SiC sublimation are presented. Solutions to increase the ESD robustness such as a Zener diode integration or the use of Al2O3 dielectric for passivation are therefore proposed in this article

Robustesse de MESFET SiC face aux décharges électrostatiques

National audienceL'émergence des composants de puissance commercial en carbure de silicium (SiC) dans notre société s'accentue d'années en années mais certaines de leurs faiblesses perdurent. Dans ce travail nous étudierons l'impact de décharges électrosta-tiques (ESD) sur différents MESFET et nous montrerons que la faiblesse principale est intrinsèquement liée aux propriétés de son diélectrique de passivation le plus commun, le SiO2. Une analyse de ce composant voué à fonctionner en conditions sévères définira les limites actuelles de cette technologie en terme de robustesse aux ESD. Mots-clés – SiC, MESFET, stress ESD, fiabilité, oxyde de passiva-tion, Lock'in thermographie, thermographi infrarouge active, robus-tess

Performances dynamiques des transistors FLYMOSTM 65 Volts à canal N

National audienceDans ce papier, un transistor FLYMOS™ 65V est caractérisé en commutation pour la première fois dans le but d'être comparé à un transistor VDMOS conventionnel. Il s'avère que les mesures de capacités inter-électrodes et de gate charge des deux composants sont comparables. Une étude comparative, à l'aide de simulations 2D, de deux structures de même tenue en tension nous a permis de conforter ces résultats, confirmant l'hypothèse que l'insertion d'îlot flottants n'entraînait pas de phénomène parasite ou nouveau, dans le cas d'îlots faiblement dopés