Aging study of silicon nanowires used as piezoresistive detection gauges for achieving inertial MEMS sensors.
Today’s sensors are present in all areas: housing, automotive... Thanks to recent developments in microelectronics, new generations of sensors combine high performance, small size and low cost. In this context, CEA-LETI has proposed an innovative concept called M&NEMS for the realization of inertial sensors such as accelerometers, magnetometers and gyroscopes. The M&Nems concept combines MEMS and NEMS to take advantage of the great inertia generated by a MEMS mass and the high detection sensitivity of piezoresistive silicon nanowires. Demonstrators have already been carried out and have shown the good potential of the M&Nems concept. One of the main challenges which remain to overcome is the reliability of sensors based on this concept and specifically the reliability of the piezoresistive nanowires. The research work will be mainly focused on the study of the failure modes of these piezoresistive nanowires gauges i.e. the identification of physical phenomena and the development of failure models. In order to do this study, a first preliminary work will be focused on the physical mechanisms which manage the electrical conduction in the nanowires: piezoresistivity, charge trapping, relaxation field effect ... The work will then continue by the study of the failure modes of nanowires, the goal will be to understand and model the physical aging of these nanowires: it will be possible to rely on the knowledge of the physics of nanowires conduction but also play with the physical parameters of these nanowires such as silicon doping, the process fabrication, the packaging technique, the thermomechanical stresses, the scale effect due to surface / volume ratio, or the surface condition. Finally, models of aging will allow proposing and validating technological choices to ensure the nanowires lifetime depending on operating conditions of the sensors.
Realistic motion generation for anthropomorphic systems
This work is devoted to Digital Human motion generation, for manufacturing (specifically, for design, maintenance, operator training, workstation design and ergonomics, ...), health (postures for surgery, rehabilitation, ...), or entertainment industry (animation for games, movies,...).
Based on complementary skills and developments of Gepetto LAAS team, and CEA LIST team, in terms of path planning (HPP), dynamic motion control of anthropomorphic systems, the objective of this post doc is to combine both approaches, a global one, dealing mainly with geometric and quasi-static constraints and characteristics, and a local one, dealing with dynamics and taking into account human movement characteristics (motor primitives, minimizing cost criteria, etc ...).
Contribution to the metrological traceability of emerging alpha-emitting radiopharmaceuticals in the framework of the european AlphaMet project (Metrology for Emerging Targeted Alpha Therapies)
The Laboratoire national Henri Becquerel (LNE-LNHB) at CEA/Saclay is the laboratory responsible for the french references in the field of ionizing radiation. The LNHB is involved in the european EPM AlphaMet (Metrology for Emerging Targeted Alpha Therapies) submitted under the Metrology support for Health call (2022) to provide metrological support for clinical and preclinical studies; it began in September 2023 for a total duration of three years. The project comprises four Work Packages (WP) targeting different issues, with WP1 in particular dedicated to activity metrology and nuclear data measurements for imaging and dosimetry. This project aims at to improve the metrological traceability of emerging alpha-emitting radiopharmaceuticals such as 211At, 212Pb/212Bi, 225Ac.
The candidate will participate in the various tasks defined as part of the European AlphaMet project in which the LNHB is involved. Radiation-matter simulations will be carried out to study the response of the laboratory's ionisation chambers in various situations concerning: (i) the evolution of the response during the in-growth of the ?-emitting progeny of 225Ac, (ii) the quantification of the influence of the 210At impurity in the case of the measurement of 211At, and (iii) the search for a long-lived radionuclide surrogate of 212Pb for the quality control of dose calibrators. The candidate will also be involved in setting up a new device aimed at improving the linearity of the measurement of half-life with an ionization chamber. During the post-doctoral stay at LNHB, the candidate will interact with the various partners in the AlphaMet project (activity metrology laboratories, hospitals, clinical study centres).
The initial duration of the post-doctorate is 12 months (renewable) at the Laboratoire National Henri Becquerel (CEA/Saclay). It is hoped to start in the first half of 2024.
Model evolution management and mastering
Designing ever more complex systems needs for new paradigms in order to face all the new challenges as improving safety while reducing time and cost to market. Paradigms, mainly active models and model transformations, promoted by model-driven engineering are providing efficient solutions to deal with those issues. However, as promoted in the series of international workshops on model and evolution (www.modse.fr), model (co-)evolution and consistency management become crucial activities to cope with the natural changes of any system. In fact, there is an increasing need for more disciplined techniques and engineering tools to support a wide range of model evolution activities, including model-driven system evolution, model differencing, model comparison, model refactoring, model inconsistency management, model versioning and merging, and (co-)evolution of models.
As part of this project, the LISE want especially to consider model evolution management under both next perspectives:
- The first issue is to enable modelers to manage the evolution of their models. They should be able to follow the changes that have been made within a model by providing as for example “track changes” mode in the modeling environment.
- The second issue concerns the problem of model versioning. The users need here to manage and use multiple versions of their models in a collaborative way.
Development of new spectrometric methods for the characterization of uranium-bearing ore
This subject aims at developing new methods of X/gamma-ray spectrum analysis for the characterization of uranium-bearing ore, enabling to process data obtained in the framework of nuclear mining activities. This subject will be developped into two parts. The first part will concern the processing of complex gamma-ray spectra, obtained using different types of medium-resolution scintillators (such as NaI or LaBr3 detector). The main purpose of this part will be related to the processing of complex regions of interest using deconvolving methods by non-parametric Bayesian inference, notably by using the SINBAD code, initially developed by CEA LIST for the processing of HPGe spectra. The second part of the subject will concern the analysis of low-resolution spectra obtained using a NaI detector in order to obtain a spectrometric information. In this case, a traditional approach based on the analysis of photoelectric peaks is not conceivable. The problem will be studied in the form of an inverse problem using a model of the detector response and a reconstruction, using an approach analogous to computed tomography. The performances of different types of reconstruction algorithms will be studied (EM analysis, non-parametric Bayesian approach).
Planning energy consumption within an eco-district
Energy consumption and production are changing, and the birth of eco-districts is now a reality which is a continuation of these changes. Eco-districts consists in grouping within the same territory entities which consume or produce energy and in managing these resources locally.
Alongside these developments, homes, shops and even offices are increasingly equipped with communicating sensors and intelligent devices that can be controlled remotely. It is therefore possible to control these devices taking into account several factors: the financial or environmental cost of energy consumed, the respect of comfort desired by the people and the intent of the directors of the eco-district. Many algorithms have been developed in order to plan and control devices more or less autonomous, while expert systems have often been excluded because of their lack of expressiveness in this area. The goal of this postdoctoral fellowship is to check if fuzzy expert systems can be used to plan devices which consume a source of energy.
Development of an hermetic thin flim packaging for RF MEMS switches
Leti has developed for many years a RF MEMS switch process which have demonstrated RF performances at the state-of-the-art as well as a process maturity level closed to industrial standards. To finalize its component and especially to ensure long-terms reliability level for space applications, Leti is today developing an innovative hermetic thin film packaging process.
The applicant will join a project team working on the development of this new technological brick. In a first step, the applicant will be in charge of the design of the process test vehicles, of the follow-up of their silicon batches fabrication in clean room and of their characterization during the process. In a second step, the applicant will perform a modeling study to optimize the design of the switches integrating this new packaging. In particular, he will propose new designs for mid RF power applications. Finally, the applicant will be in charge of the follow-up of the realization of silicon batches for the RF MEMS switches demonstrators. He will then supervise and participate to all the characterization studies on packaged components.
New electrode materials for Na-ion batteries
Na-ion battery is a challenging technology to replace Li-ion battery as it is cost competitve and may allow better cycle life. Sodium has also similar property to Lithium (light and electronegative element).
The eletrochemistry of the sodium is somewhat different of lithium with much less studies reported in the litterature.
The work will consist in the elaboration and characterization of promising electrode materials for Na-ion batteries.
Outgassing studies for advanced lithography
This work address a "post doc" person. The frame work of this subject is a advanced lithography multifaisceaux Ebeam development project. Within this project framework, an multiEbeam tool is developed in a international partnership context.
Strong contamination constraints of the projection optic are identified due to resists outgassing during theirs activations by electronic expositions. Layers contamination due to resists outgassing will be studied. The candidate will be in charge to carry out outgassing studies on various resist samples in support to the existing team and using Leti outgassing studies tool and characterization tools available on Leti (BEM, XPS, interferometer,...).
Candidate will implement methodologies already developed in Leti (pumping speed, outgassed elements identification,...) and will make contribution to improvement all of these methods. It will also supervise realization of objects useful for outgassing studies(Ebeam projection optics simulator) which will be carried on Leti. The candidate will carry out electron beam characterization on the outgassing tool and could be force of proposal for improvement. He will also take charges characterization of contaminants layers. The candidate will evolved in advanced lithography context and will be in close collaboration with international teams. English is needed.
Micro-energy sources for biomedical applications
There is a growing interest towards wireless implantable systems for in vivo biomedical applications. However, such implantable systems have a limited lifetime determined by the battery capacity. CEA LITEN is working on innovative miniaturized systems integrating an energy harvesting component with a rechargeable battery. This type of micro-systems will be used for powering sensors or other implantable medical devices. The post-doctoral researcher will work on the design, the fabrication and the characterization of demonstrators consisting of the energy harvesting component, the battery and a power management circuit. Numerical simulations could also be performed, with the help of specialized engineers. The characterization of the demonstrators and the numerical simulation results will allow the post-doctoral researcher to propose innovative solutions for optimizing the system. The post-doctoral researcher will work in a multi-disciplinary team, which requires strong abilities for team working and communication.