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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Radiation Induced Effects in Electronic Devices and Radiation Hardening By Design Techniques

Walldén, Johan January 2014 (has links)
The aim with this thesis has been to make a survey of radiation hardened electronics, explaining why and how radiation affects electronics and what can be done to harden it. The effects radiation have on electronics in general and in specific commonly used devices are explained qualitatively. The effects are divided into Displacement Damage (DD), Total Ionizing Dose (TID) and Single Event Effects (SEEs). The devices explained are MOSFETs, Silicon On Insulator (SOI) transistors, 3D-transistors, Power transistors, Optocouplers, Field Programmable Gate Arrays (FPGAs), three dimensional circuits (3D-ICs) and Flash memories. Different radiation hardening by design (RHBD) techniques used to reduce or to remove the negative effects radiation induces in electronics are also explained. The techniques are Annular transistors, Enclosed source/drain transistors, Guard rings, Triple Modular Redundancy (TMR), Dual Interlocked Storage Cells (DICE), Guard gates, Temporal filtering,Multiple drive, Charge dissipation, Differential Charge Cancellation (DCC), Scrubbing, Lockstep, EDAC codes and Watchdog timers.
2

Modeling of displacement damage in silicon carbide detectors resulting from neutron irradiation

Khorsandi, Behrooz 08 March 2007 (has links)
No description available.
3

Analyse des effets des déplacements atomiques induits par l’environnement radiatif spatial sur la conception des imageurs CMOS / Analysis of displacement damage effects on CMOS image sensor design

Virmontois, Cédric 23 March 2012 (has links)
L' imagerie spatiale est aujourd'hui un outil indispensable au développement durable, à la recherche et aux innovations scientifiques ainsi qu’à la sécurité et la défense. Fort de ses excellentes performances électro-optiques, de son fort taux d’intégration et de la faible puissance nécessaire à son fonctionnement, le capteur d’images CMOS apparait comme un candidat sérieux pour ce type d’application. Cependant, cette technologie d’imageur doit être capable de résister à l’environnement radiatif spatial hostile pouvant dégrader les performances des composants électroniques. Un nombre important d’études précédentes sont consacrées à l’impact des effets ionisants sur les imageurs CMOS, montrant leur robustesse et des voies de durcissement face à de telles radiations. Les conclusions de ces travaux soulignent l’importance d’étudier les effets non-ionisants, devenant prépondérant dans les imageurs utilisant les dernières évolutions de la technologie CMOS. Par conséquent, l’objectif de ces travaux de thèse est d’étudier l’impact des effets non-ionisants sur les imageurs CMOS. Ces effets, regroupés sous le nom de déplacements atomiques, sont étudiés sur un nombre important de capteurs d’images CMOS et de structures de test. Ces dispositifs sont conçus avec des procédés de fabrication CMOS différents et en utilisant des variations de règle de dessin afin d’investiguer des tendances de dégradation commune à la technologie d’imager CMOS. Dans ces travaux, une équivalence entre les irradiations aux protons et aux neutrons est mise en évidence grâce à des caractéristiques courant-tension et des mesures de spectroscopie transitoire de niveau profond. Ces résultats soulignent la pertinence des irradiations aux neutrons pour étudier les effets non-ionisants. L’augmentation et la déformation de l’histogramme de courant d’obscurité ainsi que le signal télégraphique aléatoire associé, qui devient le facteur limitant des futures applications d’imagerie spatiale, sont évalué et modélisés. Des paramètres génériques d’évaluation des effets des déplacements atomiques sont mis en évidence, permettant de prévoir le comportement des capteurs d’images CMOS en environnement radiatif spatial. Enfin, des méthodes d’atténuation et des voies de durcissement des imageurs CMOS limitant l’impact des déplacements atomiques sont proposées. / Today, space imaging is an essential tool for sustainable development, research and scientific innovation as well as security and defense. Thanks to their good electro-optic performances and low power consumption, CMOS image sensors are serious candidates to equip future space instruments. However, it is important to know and understand the behavior of this imager technology when it faces the space radiation environment which could damage devices performances. Many previous studies have been focused on ionizing effects in CMOS imagers, showing their hardness and several hardening-by-design techniques against such radiations. The conclusions of these works emphasized the need to study non-ionizing effects which have become a major issue in the last generation of CMOS image sensors. Therefore, this research work focuses on non-ionizing effects in CMOS image sensors. These effects, also called displacement damage, are investigated on a large number of CMOS imagers and test structures. These devices are designed using several CMOS processes and using design rule changes in order to observe possible common behaviors in CMOS technology. Similarities have been shown between proton and neutron irradiations using current-voltage characteristics and deep level transient spectroscopy. These results emphasize the relevance of neutron irradiations for an accurate study of the non-ionizing effects. Then, displacement damage induced dark current increase as well as the associated random telegraph signal are measured and modeled. Common evaluation parameters to investigate displacement damage are found, allowing imager behavior prediction in space radiation environment. Finally, specific methods and hardening-by-design techniques to mitigate displacement damage are proposed.
4

Compréhension des mécanismes physiques à l'origine des dégradations électriques extrêmes des pixels dans les capteurs d'images irradiés / Understanding of physical mechanism causing extreme electrical degradation in pixels of irradiated imager

Ursule, Marie-Cécile 26 September 2017 (has links)
Les capteurs d'images sont utilisés dans diverses applications spatiales : observation spatiale, calcul d'attitude etc. Ces capteurs évoluent dans l’environnement spatial dont les rayonnements entraînent une dégradation de leurs performances. Parmi les paramètres impactés, nous nous intéressons au courant d'obscurité des pixels. Ce courant parasite correspond à la génération de porteurs de charges sans lumière par simple excitation thermique, induisant l'augmentation du bruit de fond des images. Les pixels fortement dégradés sont particulièrement pénalisants pour les missions spatiales. Cet effet pousse donc la communauté spatiale à développer des méthodes de prédiction performantes. L'ONERA a développé une méthode originale de prédiction des courants d'obscurité basée sur la méthode de Monte Carlo et la librairie GEANT4. L’objectif de la thèse est d’améliorer la prédiction de l’outil. Dans un premier temps, nous avons modifié l'outil numérique pour des cas extrêmes de modélisations pour lesquels les modélisations Monte Carlo sont trop longues. Pour cela, nous avons développé des méthodes utilisant des simplifications statistiques. Dans un second temps, nous avons étudié l’influence de la géométrie du pixel sur le courant d'obscurité. L’idée est de suivre les cascades de dégradations générées par les particules spatiales et de déterminer si ces cascades restent confinées au sein du pixel impacté ou si elles se propagent dans les pixels voisins. Enfin, nous avons élaboré dans notre outil un modèle simulant les mécanismes liés au champ électrique potentiellement responsables des dégradations les plus élevées, les effets Poole-Frenkel et tunnel assisté par phonons. / Image sensors are used in various space applications: space and earth observations, attitude calculation etc. Those sensors are very sensitive to the space environment whose radiations lead to a degradation of their performances. Among the different impacted parameters, we are interested in the increase of dark current in the pixels. This parasitic current is caused by the thermal generation of charge carriers without any light excitation inducing the increase of the background noise on the images. Some pixels exhibiting the highest degradation are particularly disadvantageous for space missions. They can be critical for some missions and impose to the space community to develop effective prediction methods. ONERA developed an original method to predict dark current induce by the space radiations, based on a Monte Carlo method and the GEANT4 library. The objective of the PhD is to improve the performances of the tool. The approach of this work is first to modify the numerical tool for extreme cases of modelling (i.e. high fluencies or huge pixel volume) for which the Monte Carlo simulations are too long. In order to reduce this computation time, we developed calculation methods using statistical simplifications. In a second part, we studied the influence of the pixel geometry on the dark current. The idea is to follow the degradation cascades created by space particles and to determine if those cascades are contained in the impacted pixel or if they reach neighbor pixels. Finally, we modelled in our tool the physical mechanisms potentially responsible of the highest degradations linked to the electric field, the Poole-Frenkel effect and the phonon assisted tunneling.
5

The Effects of Nuclear Radiation on Schottky Power Diodes and Power MOSFETs

Kulisek, Jonathan Andrew 23 August 2010 (has links)
No description available.
6

Hardness assurance testing and radiation hardening by design techniques for silicon-germanium heterojunction bipolar transistors and digital logic circuits

Sutton, Akil Khamisi 04 May 2009 (has links)
Hydrocarbon exploration, global navigation satellite systems, computed tomography, and aircraft avionics are just a few examples of applications that require system operation at an ambient temperature, pressure, or radiation level outside the range covered by military specifications. The electronics employed in these applications are known as "extreme environment electronics." On account of the increased cost resulting from both process modifications and the use of exotic substrate materials, only a handful of semiconductor foundries have specialized in the production of extreme environment electronics. Protection of these electronic systems in an extreme environment may be attained by encapsulating sensitive circuits in a controlled environment, which provides isolation from the hostile ambient, often at a significant cost and performance penalty. In a significant departure from this traditional approach, system designers have begun to use commercial off-the-shelf technology platforms with built in mitigation techniques for extreme environment applications. Such an approach simultaneously leverages the state of the art in technology performance with significant savings in project cost. Silicon-germanium is one such commercial technology platform that demonstrates potential for deployment into extreme environment applications as a result of its excellent performance at cryogenic temperatures, remarkable tolerance to radiation-induced degradation, and monolithic integration with silicon-based manufacturing. In this dissertation the radiation response of silicon-germanium technology is investigated, and novel transistor-level layout-based techniques are implemented to improve the radiation tolerance of HBT digital logic.
7

Micro-mechanics of irradiated Fe-Cr alloys for fusion reactors

Hardie, Christopher David January 2013 (has links)
In the absence of a fusion neutron source, research on the structural integrity of materials in the fusion environment relies on current fission data and simulation methods. Through investigation of the Fe-Cr system, this detailed study explores the challenges and limitations in the use of currently available radiation sources for fusion materials research. An investigation of ion-irradiated Fe12%Cr using nanoindentation with a cube corner, Berkovich and spherical tip, and micro-cantilever testing with two different geometries, highlighted that the measurement of irradiation hardening was largely dependent on the type of test used. Selected methods were used for the comparison of Fe6%Cr irradiated by ions and neutrons to a dose of 1.7dpa at a temperature of 288&deg;C. Micro-cantilever tests of the Fe6%Cr alloy with beam depths of 400 to 7000nm, identified that size effects may significantly obscure irradiation hardening and that these effects are dependent on radiation conditions. Irradiation hardening in the neutron-irradiated alloy was approximately double that of the ion-irradiated alloy and exhibited increased work hardening. Similar differences in hardening were observed in an Fe5%Cr alloy after ion-irradiation to a dose of 0.6dpa at 400&deg;C and doses rates of 6 x 10<sup>-4</sup>dpa/s and 3 x 10<sup>-5</sup>dpa/s. Identified by APT, it was shown that increased irradiation hardening was likely to be caused by the enhanced segregation of Cr observed in the alloy irradiated with the lower dose rate. These observations have significant implications for future fusion materials research in terms of the simulation of fusion relevant radiation conditions and micro-mechanical testing.

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