Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PostDocs : selection by topics

Shape optimization for optical computation

Département d'Optronique (LETI)

Laboratoire des Capteurs Optiques



Context CEA - LETI is one of the Europe's leading research centers in microelectronics. This post-doctoral position is proposed within the framework of the CLEAR CARNOT project, involving two departments of CEA - LETI. Namely, the DOPT department specializes in the design, manufacture and characterization of optoelectronic components while the DACLE department performs research on embedded systems and innovative computational architectures. Research topic / Missions Although several extremely compact components performing more or less complex unitary functions have been designed and manufactured in recent years, no practical application of numerical shape optimization methods has emerged to date in the field of integrated photonics. Building on the recent development of optical computation, particularly in the wake of neural network and machine learning, we aim to demonstrate the feasibility (design, fabrication and test) and the applicative interest of integrated optical calculation circuits obtained by shape optimization techniques. The candidate will participate in the choice of the optical computation prototype architecture, and will be in charge of the photonic circuit design (conventional circuit, shape optimized circuit, and finally reconfigurable circuit). He/she will rely on an existing toolbox, dedicated to shape optimization of photonic components, developed as part of an ongoing work. The work should lead to theoretical developments as well as applications, with publications in international journals. Required skills Candidates will have completed a PhD in applied mathematics, mathematical physics or related fields. He/she should demonstrate both theoretical and computational skills. Implementations will be performed in the MATLAB language. Knowledge in shape optimization and an interest for photonics would be greatly appreciated.

Physisorption of chemical species on sensitive surfaces during transfer in controlled mini-environment in microelectronics industry

Département Technologies Silicium (LETI)




A characterization platform based on the connection concept between process and characterization tools through the use of a transfer box under vacuum was implemented allowing a quasi in-situ characterization of substrates (wafers) of the microelectronics. Currently, this transfer concept based simply on static vacuum inside a carrier box is satisfactory regarding the residual O or C on the surface of especially sensitive materials (Ge, Ta, Sb, Ti?) and the MOCVD layers growth on GST or III/V surfaces. Its optimization for more stringent applications (molecular bonding, epitaxy?) in terms of contamination surface prevention requires studies the understanding of the physico-chemical evolution of the surfaces. The proposed work will be focused on physico chemical studies of the evolution and molecular contamination of surfaces during transfers and will take place in clean room. XPS, TD-GCMS and MS coupled to the carrier itself (to be implemented) will be used to address the sources (wall, seals, gaseous environment?) of the adsorbed chemical species implied and to determine the physisorption mechanisms on the substrates. The studied surfaces will be sensitive to the contaminants in such a way than the box environment impact will be extracted and studied parameters will be the nature of polymer seal used, the carrier box thermal conditioning, the vacuum level, the use of low pressure gaseous environment in the carrier (gas nature, pressure level?).

Study of substrate coupling in millimeter wireless circuits

Département Architectures Conception et Logiciels Embarqués (LIST-LETI)

Laboratoire Architectures Intégrées Radiofréquences



The candidate will study substrate coupling in millimeter wireless circuit. He will demonstrate the influence of silicon substrate on millimeter circuit design The first task will consist in establishing the state of the art of substrate reduction technics on millimeter chip. The influence between building blocks at layout level will be analyzed. Parasitic noise effects, frequency and power spurious will be studied with coupling substrate tool. Specifications for layout design in order to reduce spurious will be done, especially for power, analog and digital applications. A design methodology will be proposed with this results.

Development of femtosecond Fiber Bragg Grating acoustic receivers for the Structural Health Monitoring using passive acoustic tomography


Laboratoire Capteurs et Architectures Electroniques



The proposed post-doctoral fellowship is part of a transverse project initiated by the CEA and which consists in developing a prototype of a continuous monitoring system of a metallic structure (pipe for example) using fiber Bragg gratings acoustic receivers and passive imaging (or passive tomography). It aims to demonstrate the relevance of the SHM (Structural Health Monitoring) concept for nuclear facilities using optical fiber sensors operating in continuous and in extreme environment. This project is based on two recent developments: new generation of fiber Bragg gratings developed for severe environments and defect imaging algorithms based on ambient noise analysis. A demonstration of elastic wave reconstruction from passive algorithm applied to fiber Bragg gratings was carried out at the CEA in 2015, which is a world first, patented. The project aims more particularly to produce a demonstrator and to equip a pipeline on a test loop. It will provide input data relating to the ability of a moving fluid to generate elastic waves that can be analyzed in passive tomography.

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