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Offers : 24

Theoretical and experimental studies of the polarized light’s propagation into OLED structure

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Start date : 01/12/2021

offer n° PsD-DRT-22-0018

In collaboration with chemists from CEA Saclay and the University of Rennes, Leti’s LCEM laboratory is interested in new chiral molecules for OLED (Organic Light Emitting Device) sources able to emit circularly polarized light (CP). The interest of these CPOLED sources is multiple and encompasses both micro-screens and healthcare applications. While the state of the art is quite extensive on the chemical part, few studies have looked at the generation and transport of light in CPOLEDs components.Likewise, the conditions for measuring the polarity of the light emitted are not very detailed in the existing literature.

At the LCEM laboratory, where these chiral molecules are integrated into CPOLED devices, the goal is to design OLED architectures that can better preserve the polarization of light. To do this, it is essential to understand the propagation of light in OLED stacks from a theoretical and experimental point of view. This work is part of a larger collaboration set up in the ANR “i-chiralight” project.

In this context, we are proposing a study which will take place in two phases.

– Study of simple emitting materials: The materials to be studied will be thin layers deposited under vacuum using evaporation’s system of thin layers available in the laboratory. The organic materials used will be supplied by our chemical partners in Saclay or Rennes. Optical characterizations such as ellipsometry,photoluminescence, etc. will be carried out in order to assess the performance of molecules in terms of emission efficiency but also in terms of the rotational power of light. For this last point, a model able to calculate all the terms of the Müller matrices is under development and the validation of this one will be a work to be carried out by the post-doctoral fellow.

– Study of complete OLED components: In the second phase of this work, we will focus on the complete OLED system by studying the propagation of optical modes in the stack of the different layers const

  • Keywords : Défis technologiques, Sciences pour l'ingénieur, Photonique, imageurs et écrans, DOPT, Leti
  • Laboratory : DOPT / Leti
  • CEA code : PsD-DRT-22-0018
  • Contact : etienne.quesnel@cea.fr

Evaluation of RF system power consumption for joint system-technology optimization

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Start date : 01/05/2021

offer n° PsD-DRT-21-0081

To be able to increase and optimize wireless transmission systems based on a hybridization of technologies, it is strategic to be able to quickly evaluate the capabilities of these technologies and to adapt the associated architecture as best as possible. To this end, it is necessary to implement new approaches to global power management and optimization.

The work of this post-doctoral contract is at this level.

The first step will be to develop some new power consumption models of the RF transceivers building blocks (LNA, Mixer, Filter, PA, …). A modelization approach has already been tested and validated in the group. In the next step, it will be needed to link the performances of the overall wireless system to the building blocks characteristics. Lastly, the optimization will be applied thanks to an efficient solution. Lastly, the proposed approach will be validated in the optimisation of a multi-antenna millimeter wave wireless system. An evaluation methodology specific to 3D will also be put in place

  • Keywords : Défis technologiques, Sciences pour l'ingénieur, Electronique et microélectronique - Optoélectronique, Réseaux de communication, internet des objets, radiofréquences et antennes, DSYS, Leti
  • Laboratory : DSYS / Leti
  • CEA code : PsD-DRT-21-0081
  • Contact : dominique.morche@cea.fr

Optomechanical resonators for (bio)particle mass sensing in biomedical applications

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Start date : 01/04/2022

offer n° PsD-DRT-22-0051

Background

Nano-Electro-Mechanical systems (NEMS) generate particular interest in a wide range of applications, from quantum measurements to biotechnology. The goal of the project is to characterize biological particles in mass ranges currently unachievable by conventional techniques with possible applications in disease diagnosis, air quality control and characterization of novel therapeutic agents.

Thanks to LETI’s prime technological means and NEMS expertise, major technological milestones have been achieved (Sage et al. Nature Commun. 2015; Sansa et al. Nature Nanotechnol. 2016). In parallel with these efforts, LETI has been developing optomechanics as a high-performance transduction method, allowing ultra-sensitive detection of NEMS resonators with applications in mass spectrometry (Sansa et al. Nature Commun. 2020).

The EDyP team of the Interdisciplinary Research Institute in Grenoble (IRIG) has extensive expertise in high-end mass spectrometry instrumentation and its use to achieve protein identification and quantification. LETI and IRIG initiated a joint effort towards developing a new generation of NEMS based mass spectrometer, which led to the first measurement of viral particles above 100 MDa using nanomechanical resonators (Dominguez-Medina et al. Science 2018).

Project

The objective of the post-doc is to develop the next generation of NEMS mass spectrometer for biological detection using optomechanical resonator arrays. The hired person will integrate the MEMS team in LETI, where he/she will characterize optomechanical resonators already available. Then, she/he will work in close collaboration with the IRIG team to adapt the current mass spectrometry set-up at IRIG to the new sensors, and to perform mass spectrometry measurements.

  • Keywords : Défis technologiques, Sciences pour l'ingénieur, Technologies pour la santé et l’environnement, dispositifs médicaux, DCOS, Leti
  • Laboratory : DCOS / Leti
  • CEA code : PsD-DRT-22-0051
  • Contact : marc.sansaperna@cea.fr

Developement of relaxed pseudo-substrate based on InGaN porosified by electrochemical anodisation

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Start date : 01/03/2021

offer n° PsD-DRT-21-0035

As part of the Carnot PIRLE project starting in early 2021, we are looking for a candidate for a post-doctoral position of 24 months (12 months renewable) with a specialty in material science. The project consists in developing a relaxed pseudo-substrate based on III-N materials for µLEDs applications, especially for emission in red wavelength. The work will focus on developing an InGaN-based epitaxy MOCVD growth process, on an innovative substrate based on electrochemically anodized and relaxed materials. He (She) will have characterize both the level of relaxation of the re-epitaxied layer and its crystalline quality. These two points will promote the epitaxial regrowth of an effective red LED. The candidate will be part of the team, working on the PIRLE project, will be associated to the work on red LED growth and its optical and electro-optical characterizations.

  • Keywords : Défis technologiques, Physique de l'état condensé, chimie et nanosciences, Matériaux et procédés émergents pour les nanotechnologies et la microélectronique, Physique du solide, surfaces et interfaces, DPFT, Leti
  • Laboratory : DPFT / Leti
  • CEA code : PsD-DRT-21-0035
  • Contact : carole.pernel@cea.fr

Energy-Efficiency enhancement in cell-free massive MIMO based 6G networks

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Start date : 01/03/2022

offer n° PsD-DRT-22-0030

An alternative network infrastructure is appealing as the ultimate enabler of energy-efficiency (EE) and spectral-efficiency (SE), it is called cell-free massive MIMO (CF-mMIMO). In this latter, the cell boundaries are avoided and many access points (APs) share the different antennas at the (virtual) base station. Consequently, it results in smaller and lighter radio modules with only few antennas per AP.

However, cell-free massive MIMO can be economically attractive only if its implementation is based on low-cost hardware that, however, generates severe hardware imperfections (HWIs). Such HWIs affect the system performance and it is considered as the major bottleneck in cell-free massive MIMO systems in practice.

The main goal of the Postdoc is to explore the potentiality of distributed optimization methods and machine learning (ML) algorithms to achieve up substantial energy saving gains, compared to the existing literature, by mitigating HWIs in power-efficient RF transceivers. The postdoc will investigate sophisticated and comprehensive digital signal processing solutions to achieve substantial energy-efficiency enhancement in CF-mMIMO, by mitigating HWIs in power-efficient transceivers.

The candidate should have a PhD degree in Telecommunications, low layers. She/he should have diverse skills in signal processing, machine learning and mathematics. Some knowledge of massive MIMO systems are desirable. Programming software: Matlab, Python.

  • Keywords : Défis technologiques, Data intelligence dont Intelligence Artificielle, Réseaux de communication, internet des objets, radiofréquences et antennes, DSYS, Leti
  • Laboratory : DSYS / Leti
  • CEA code : PsD-DRT-22-0030
  • Contact : rafik.zayani@cea.fr
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