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

PhD : selection by topics

Atomic-level control over ultrathin 2D layers of Transition Metal Dichalcogenides obtained by a Molecular Layer Deposition route

Département technologies silicium (LETI)

Autre laboratoire

01-10-2019

SL-DRT-19-1048

denis.rouchon@cea.fr

2D-materials, especially transition metal dichalcogenides (TMD), have recently received considerable attention since they are emerging as a class of exceptional semiconductor materials with many potential applications (supercapacitors, batteries, electronics and opto-electronics, flexible electronics ...). However, a sizeable bottleneck for their full deployment stems from the lack of scalable fabrication methods with atomic scale precision. Both Atomic Layer Deposition (ALD) and Molecular Layer Deposition (MLD) are based on sequential, self-limiting surface reactions that allow conformal film growth with precise thickness control. They are ideal techniques for depositing scalable ultrathin inorganic and organic films. The thesis project aims to achieve the synthesis of intermediate layered metal-organic hybrid films by a combination of Atomic Layer Deposition and Molecular Layer Deposition (ALD/MLD) followed by mild thermal treatment (annealing) en route to the crystalline final phase. The targeted materials are first TiS2 then SnS2. We want to explore with the thermal treatment a possible route to synthesize graphitic interfaces which could allow new electrodes or electrical contacts. Provide an atomic-level insight and control over the growth by combining ab initio calculations (not to be performed by the PhD student) and in situ chemical and structural studies performed during the growth and thermal treatment, i.e. in situ X-ray absorption and scattering with custom-built equipment, in situ Raman scattering, residual gas analysis, ellipsometry

Optical laser waveguides III-V (AsGa/InP) growth directly onto SOI-300mm.

Département d'Optronique (LETI)

Laboratoire d'integration technologique pour la photonique

01-10-2019

SL-DRT-19-1055

christophe.jany@cea.fr

For more than 25 years, the heart of telecom networks has become one of the fields of application of the III-V components (InP_like, and AsGa_like). This field is based on the transmission of IR waves in optical fibers, powered by laser sources in III-V materials. Over the past ten years, a new technological path has been developed, based Silicon-Photonics, which makes it possible to lower manufacturing costs by increasing integration (3D integration, Wafer Level Packaging). The approach usually chosen here consists of a molecular bonding of a III-V wafer (epitaxial) on an SOI previously structured optical guides. A technological treatment is then applied to make III-V transmitter guides connected to the silicon guides. Since less than 5 years; a new integration scheme is developing, it is the direct epitaxy of III-V materials on silicon. For 3 years, the CEA / LETI laboratories, already experts in the development of photonics on Silicon by bonding process, have decided to investigate this highly innovative approach with high potential. The proposed thesis will thus rely heavily on the CNRS / LTM laboratory, which has been developing for the last 4 years new MOCVD epitaxial concepts for III-V materials (AsGa base) on textured silicon wafer. This subject of study will enable the establishment of a new roadmap of III-V epitaxy on Silicon, with the aim of designing a new generation of photonic circuits. The PhD student will be involved both in the development of III-V materials on silicon, as well as in the design and realization of photonic circuits 2.0.

Multi-point measurement method development for uncertainties reduction of activity quantification in nuclear waste drum using gamma spectrometry

DM2I (LIST)

Laboratoire Capteurs et Architectures Electroniques

01-10-2019

SL-DRT-19-1069

adrien.sari@cea.fr

The management of radioactive waste packages is a major challenge for the nuclear industry. Characterization of the packages requires non-destructive nuclear measurement solutions in order to preserve the integrity of packages. The present thesis will focus on a concrete case of application which will consist in equipping with embedded sensors a six-axis robotic arm bearing a smear system, a contaminameter, and a gamma spectrometer. The robotic arm will allow multipoint measurements, in dose rate (with a Geiger-Müller type detector) and gamma spectrometry (with a CdZnTe detector). The drums to be characterized will have weak or medium activities, and the radioelements to be identified will be activation products and actinides. The aim of this thesis is to define a dynamic multipoint measurement method for optimizing the declaration of uncertainty associated with the quantity of interest (dose rate and activity). This thesis will include an MCNP6 simulation component and an experimental component.

Few-shot learning: Application to object detection and semantic instance segmentation

Département Intelligence Ambiante et Systèmes Interactifs (LIST)

Vision & Ingénierie des Contenus (SAC)

01-10-2019

SL-DRT-19-1084

romaric.audigier@cea.fr

Nowadays, many computer vision tasks are successfully managed by deep learning models. Those include, for example, object detection and recognition, image classification, person, gesture, action or activity recognition... which are useful in many fields of application (video-surveillance, autonomous driving, robotics, industry 4.0, medical image analysis, active assisted living, etc.). The drawback of these deep neural networks-based approaches is that they require a huge amount of annotated data during their supervised training. On the one hand, manual data annotation is a tedious and expensive task. On the other hand, data can also be rare or difficult to gather for some reasons, including privacy, safety, or ethics. It is therefore essential to design methods that learn from very few annotated samples of data. The challenge of few-shot learning is then to approach, even surpass, human ability to learn and generalize from few examples. The objective of this thesis is to propose novel methods that optimize the model ability to rapidly handle new tasks, including detecting, segmenting and recognizing new object classes. A comparative study between state-of-the-art and developed methods will be carried out on many datasets in order to quantify performance improvements, dependence on number 0of samples, as well as generalization ability relative to types of data.

Fast Atomic Layer Deposition (fast-ALD) of Transparent Conductive Oxides

Département d'Optronique (LETI)

Laboratoire des Composants Emissifs

01-10-2019

SL-DRT-19-1086

tony.maindron@cea.fr

The PhD project plans to work on optimization and understanding of fast-ALD (Atomic Layer Deposition) processes, made in a dedicated fast deposition reactor (not spatial) developed by the French company Encapsulix, for the deposition of Transparent Conductive Oxides (TCOs). The ALD deposition technology allows the deposition of thin layers of inorganic materials with a digital control of thickness, high optical quality and conformality. Traditionally, ALD primary use has been focusing on micro/nanoelectronic applications, for very thin layers, e.g. < 10 nm, because the nominal deposition rate of standard ALD tools is relatively low, 1 Å / min. The French company Encapsulix introduced the Parallel Precursor Wave (PPW) reactor architecture few years ago, which increases the deposition rate by more than an order of magnitude (12 Å / min). The CEA-LETI institute acquired an Infinity 200 fast-ALD tool at the end of 2015. It is used today for organic electronics, mainly for thin-film encapsulation of OLED using Al2O3 material. Besides Al2O3, some preliminary deposition tests of TCOs like ZnO or AZO (ZnO: Al) materials by fast-ALD have been realized recently but they show limitations to achieve optimal physical properties of the TCOs, compared to conventional ?low speed? ALD. In the case of AZO, it has been noticed some doping issues leading to AZO thin films that were far more resistive than AZO films deposited in standard ALD tools (not fast). We suspect that doping is impacted by the fast-ALD process itself. Similar observations were reported recently by a team from UNCC University (USA) working on a spatial fast-ALD technology . The first part of the PhD work will be to understand physical mechanisms involved in the solid state doping of binary TCO compounds like AZO deposited by fast-ALD. In addition to ZnO and AZO materials, the PhD student will implement and study fast-ALD deposition of SnO2. The advantage of SnO2 over ZnO compounds is a greater stability in microfabrication processes as well as a better stability under humidity storage. Mastering the deposition of this oxide in a fast-ALD tool is therefore a competitive advantage for some dedicated applications in photonics. A second part of the PhD work will consist on the study of the area selective deposition (ASD) of these TCOs. This will be made thanks to the use of Self-Assembled Monolayers (SAMs) that can be deposited in the vapor phase by a dedicated process (Molecular Vapor Deposition tool available at CEA-LETI). Study of ASD technology is today mainstream in microelectronics, for the fabrication of gate oxides for advanced transistor nodes (< 10 nm). There are opportunities for ASD diversification towards non-micro/nanoelectronic applications, e.g. optoelectronics/photonics, and towards the realization of selective deposition of micro-patterned, or even macro-patterned TCO films. This is therefore a very innovative point in this PhD project. CEA-LETI will rely on the expertise of the LTM in terms of ASD to carry out its tests. The French institute CEA-LETI is a key player in research, development and innovation in four main areas: defense and security, low carbon energies (nuclear and renewable energies), technological research for industry, fundamental research in the physical sciences and life sciences. Drawing on its widely acknowledged expertise, the CEA-LETI actively participates in collaborative projects with a large number of academic and industrial partners.

Investigation of electrochemiluminescence reactions at diamond electrodes for analytical applications

DM2I (LIST)

Laboratoire Capteurs Diamants

01-10-2019

SL-DRT-19-1092

emmanuel.scorsone@cea.fr

The PhD fellow will focus on the investigation of electrochemiluminescence (ECL) processes at boron doped diamond (BDD) electrode surfaces. ECL is a phenomenon in which photons are emitted during electrochemical reactions. It already proved to be a very promising analytical tool for sensing applications, where both high sensitivity and selectivity are needed. Indeed, it merges the advantages of chemiluminescent analysis with the absence of background optical signal, with wide possibilities for reaction control using diverse electrochemical protocols. ECL can be observed in organic solvents where both oxidized and reduced forms of luminescent species are produced simultaneously. Excitation energy is then obtained from recombination of oxidized and/or reduced species. In aqueous environments, simultaneous oxidation and reduction of luminescent species is difficult to achieve due to electrochemical splitting of water, implying the use of a co-reactant. In this case luminescent species are oxidized at the electrode together with the co-reactant, which gives a strong reducing agent after some chemical transformations. In this context, Boron Doped Diamond electrodes offer numerous advantages that have been little explored for ECL analytical applications. The candidate will demonstrate the advantages of BDD for such ECL applications, bring some new knowledge regarding the chemical/physical reactions involved, and will eventually contribute to the development of an analytical demonstrator.

108 Results found (Page 18 of 18)
first   previous  14 - 15 - 16 - 17 - 18

Voir toutes nos offres