Dynamic range optimisation of CMOS image sensors dedicated to space applications

Nowadays, CMOS image sensors are widely considered for space applications. Their performances have been significantly enhanced with the use of CIS (CMOS Image Sensor) processes in term of dark current, quantum efficiency and conversion gain. Dynamic Range (DR) remains an important parameter for a lot of applications. Most of the dynamic range limitation of CMOS image sensors comes from the pixel. During work performed in collaboration with EADS Astrium, SUPAERO/CIMI laboratory has studied different ways to improve dynamic range and test structures have been developed to perform analysis and characterisation. A first way to improve dynamic range will be described, consisting in improving the voltage swing at the pixel output. Test vehicles and process modifications made to improve voltage swing will be depicted. We have demonstrated a voltage swing improvement more than 30%. A second way to improve dynamic range is to reduce readout noise A new readout architecture has been developed to perform a correlated double sampling readout. Strong readout noise reduction will be demonstrated by measurements performed on our test vehicle. A third way to improve dynamic range is to control conversion gain value. Indeed, in 3 TMOS pixel structure, dynamic range is related to conversion gain through reset noise which is dependant of photodiode capacitance. Decrease and increase of conversion gain have been performed with different design techniques. A good control of the conversion gain will be demonstrated with variation in the range of 0.05 to 3 of initial conversion gain

Ionizing radiation effects on CMOS imagers manufactured in deep submicron process

We present here a study on both CMOS sensors and elementary structures (photodiodes and in-pixel MOSFETs) manufactured in a deep submicron process dedicated to imaging. We designed a test chip made of one 128×128-3T-pixel array with 10 µm pitch and more than 120 isolated test structures including photodiodes and MOSFETs with various implants and different sizes. All these devices were exposed to ionizing radiation up to 100 krad and their responses were correlated to identify the CMOS sensor weaknesses. Characterizations in darkness and under illumination demonstrated that dark current increase is the major sensor degradation. Shallow trench isolation was identified to be responsible for this degradation as it increases the number of generation centers in photodiode depletion regions. Consequences on hardness assurance and hardening-by-design are discussed

Effects of Grain Size and Shape of alumina aggregates on the Sinterability and Thermal Shock Resistance of Refractory Materials

The Concerted European Action on Sustainable Application of REFractories ( is a consortium created to drive sustainable refractory materials and processes in steel production. This project which runs from 2022 2025 seeks to improve the microstructure for increased sustainability and thermo mechanical performances of refractory castables. In this work, different formulations of alumina spinel refractory castables are considered The main objective is to propose a new design for the microstructure of refractory materials with improved thermo mechanical properties by considering • The nature of aggregates ( crystallinity, physical properties • The arrangement of the calcium aluminate phases network (formation temperatures, unique formation mechanisms, location and morphology

Reuse and recyclability of refractories from steel industry

Part of the CESAREF consortium, the study presented here is dedicated to the characterization of refractory material properties after usage for potential reuse and recyclability determination. The aim of this doctoral study is to provide an insight on the variation of specific materials’ key properties (such as thermal conductivity, thermal expansion, Young’s module, modulus of rupture) after operations. Mesoscale aging studies may allow to define appropriate Finite Element Models ( to foreseen operative conditions of the refractory. Furthermore, application of an adapted FMECA (Failure Modes, Effects, and Criticality Analysis) fatigue integrated approach can be a further reliable tool to better predict refractories’ lifetime. Also, MCDA (Multi Criteria Decision Approach) implementation could help in detecting the necessary strategies to define the most convenient recycling routes

Insights on numerical models to predict potential recyclability of spent refractories from steel making industry

The present study is part of the CESAREF (Concerted European action on Sustainable Applications of REFractories) doctoral network, started in late 2022. The aim of the consortium is the contribution to scientific breakthroughs inherent to refractories for steel making sector thanks to transversal competences deriving from academic and industrial realities. European green deal and circular economy targets set by EU for 2025 are also related to the massive consumption of refractory materials in the steel industry. Operative lifetimes of refractories range from hours to several months depending on their role. As a result of increasingly tightened policies and disposal costs, and due to recent supply chain shortages, end-of-life refractories recovery and recycling practices are receiving great attention. Some of the core requirements for sustainability and circularity are the reduction of open-loop and down scaling strategies, to maintain refractory materials value as long as possible, of the end-of-life materials. Over the years application of numerical models has proved to be a useful strategy for researchers facing in-use issues related to refractory materials. In this study, different finite element models (FEM) applied to end-use refractories are discussed to understand their suitability for potential recyclability prediction. Thermomechanical characterization of prior- and post-use materials allow to identify the critical issues related to numerical models' development. The comparison between empirical results and the appropriate numerical model allow us to identify suitable pathways to improve refractories sustainability

Relationships between Microstructure and Thermomechanical Behaviour - Measurements of Properties and Interpretation through Model Materials

International audienc

Relationship between microstructure and thermomechanical behaviour. Measurement of these properties and interpretation with the help of model materials

International audienc

Relationship between microstructure and thermomechanical behaviour. Measurement of these properties and interpretation with the help of model materials

International audienc

Mechanical properties of refractories: Multi‐scale composite approach from grains to material level

International audienceRefractory materials exhibit a heterogeneous microstructure consisting in coarse aggregates surrounded by fine grains that form an aggregate/matrix composite. This heterogeneous microstructure often leads to a complex mechanical behaviour during loading. This paper is devoted to the study of thermomechanical properties of several industrial and model refractory materials in relation with the evolution of their microstructure during thermal treatments. The aim is, in particular, to highlight the role of thermal expansion mismatches existing between the different phases which can induce damage at local scale. The resulting network of microcracks is well known to decrease elastic properties. Moreover, this network of microcracks can also strongly affect the thermal expansion at low temperature and the stress-strain behaviour in tension. Indeed, the occurrence of a large quantity of small precracks during the cooling stage after sintering, which enhances the development of a fracture process zone while loading, allows the decrease of the brittleness of the material which becomes in this case flexible. The large increase in strain to rupture, which results from this flexibility, is thus of a great interest for the enhancement of thermal shock resistance