Development of new processes for the fabrication of advanced interconnect structures of solar cells
The fabrication of solar cells with high performances at a reduced cost is a key challenge addressed by many research institutions and industrials worldwide. Many technological solutions are being investigated. Among them, a promising approach consists in forming narrower metal lines to limit shadowing of active areas of the cells. This work aims at replacing serigraphy by new fabrication processes able to reduce line width. For this purpose, the conducting substrate is coated by an insulating mask in which the lines are defined. The metal is then directly plated selectively onto the weakly conducting portions of the substrate, i.e. the lines, using electrolytic reactions. The process conditions will be adapted with regard to the nature of the initial conducting surfaces.
Multi-scale modelling of the structure and mobility of small defect clusters in metals
Recently, we have proposed a three dimensional periodic structure for self-interstitial clusters in body-centered-cubic metals, as opposed to the conventional two dimensional loop morphology [1]. The underlying crystal structure corresponds to the C15 Laves phase. Using Density Functional Theory and interatomic potential calculations, we have demonstrate that in a–iron these C15 aggregates are highly stable and immobile and that they exhibit large antiferromagnetic moments. They form directly in displacement cascades and they can grow by capturing self-interstitials. They thus constitute an important new element to account for when predicting the microstructural evolution of iron base materials under irradiation.
Despite their low concentration, these clusters are expected to play a crucial role in the behavior of iron and ferritic steels under irradiation and many questions remain to be elucidate: which clusters are the most stable in intermediate sizes, which are the reaction pathways which link the traditional clusters to new ones, how the new clusters interact with the dislocation loops, which are the effects of finite temperatures etc
xenon measurement by Cavity RingDown Spectroscopy to improve safety in the fast neutron reactors
Safety is a key point of the IVth generation nuclear reactors. Therefore new analytical methods are investigated for reliably detecting tracers of a nuclear reactor malfunction. This postdoctoral work aims at studying an innovative laser absorption method, Cavity RingDown Spectroscopy CDRS, to measure gaseous tracers indicating a reactor malfunction. This study is part of the research and development activity of the Physical Chemistry Department (DPC), which is partly involved in improving and developing tools and analytical methods. The optical system studies are a collaboration work with the "Laboratoire Interdisciplinaire de Physique" of the Grenoble University (France), which is a leader research laboratory in trace gas detection by laser absorption methods CRDS (Cavity RingDown Spectroscopy) and OF-CEAS (Optical Feedback Cavity Enhanced Absorption Spectroscopy).
A glow discharge was coupled to a Cavity RingDown measurement. After plasma conditions optimization, the optical set-up is able to measure below 1 part per billion Xe/Ar mixing ratios. The optical saturation of the xenon electronic transition should be considered to quantify each isotope. The optimized CRDS measurement will be characterized. The set-up could further measure krypton isotopes.
A. Pailloux & al., depot de brevet 11 62436 (2011)
P. Jacquet, A. Pailloux, submitted to J. Anal. Atom. Spectrom. (2013)
N. Sadeghi, J. Plasma Fusion Research 80 (9), pp 767-776 (2005)
Silicon nanowire elaboration for microelectronic applications
In order to realize high capacity integrated capacitor, one approach consists in developing electrode with high specific surface. In this work, we propose to perform capacitor integrating silicon nanowires. The first part of this study will be devoted to the understanding and to the optimization of Si nanowires CVD growth process. In parallel, properties of nanowires obtained by electrochemical silicon etching will be assessed and will be compared to CVD nanowires characteristics. According to the electrical performances, different strategies (metallization Silicuration…) will be envisaged in order to enhance their electrical conductivity.
New Sustainable Carbon Catalysts for PEMFC
The aim of the project is to develop and test for ORR, a mesoporous and graphitised graphene aerogel based material, presenting a hierarchical structuring allowing a better material transfer and graphitic domains increasing the durability and conductivity of the final material, and functionalised by Pt-NPs.
These graphene-based structures developed at IRIG/SyMMES possess surface chemistries and micro/meso/macro porosities that depend on the synthesis, functionalisation and drying methods used. The aim will be to increase their degree of graphitisation, and then to deposit Pt-NPs by chemical means. The electrocatalytic properties of these materials will then be tested.
Advanced meso-structural characterisation of these materials by scattering (X-ray or neutrons) methods will enable to investigate the structural properties of these new electro-catalysts. These properties will thenbe correlated to their electrocatalytic properties, and performances in fuel cell systems. This knowledge will be gained through ex-situ and operando analyses.
CIGS solar cells optimized for energy harvesting applications in indoor environments
The goal of this post-doctoral fellowship is to develop solar cells based on CIGS thin films, for energy harvesting applications (powering of small electronic autonomous devices). This research project will aim at optimizing the solar cell performances in indoor environments, i.e., under low light intensity. The post-doctoral fellow will be involved in CIGS thin film elaboration by physical vapour deposition, film characterization, solar cell realization and test.
Thermodynamic Modelling of Complex Oxides for Smart Sensors
The search for more efficient materials follows a pattern that has changed very little over the years, involving poorly automated phases of synthesis, characterization and measurement of functional properties. Although this pattern has proved its strength in creating knowledge bases, it remains ineffective because it is time-consuming and generally covers a reduced range of compositions. The project Hiway-2-mat (https://www.pepr-diadem.fr/projet/hiway-2-mat/) seeks to use high-throughput combinatorial approaches and develop autonomous configurations to explore the compositional spaces of complex oxide materials, with the aim of accelerating the discovery of materials for smart sensors. In this context, CALPHAD method is a valuable tool for materials exploration, as it can provide a number of useful insights into the role of oxidation state or oxygen partial pressure on phase stability, and on the degree of substitution of doping elements in an oxide matrix. The aim is to calculate phase diagrams of complex oxides based on available databases, either to better prepare combinatorial experiments, or to drive the autonomous robot on the fly, providing additional information for on-line characterization.
Your role will be to:
1)Perform thermodynamic simulations using CALPHAD method and Thermo-Calc Software to predict the stability range of a set of complex oxides (Ba/Ca/Sr)(Ti/Zr/Sn/Hf)O3 at different temperatures and oxygen partial pressures. In this step, the candidate will also perform a critical review of the thermodynamic data available in the literature.
2)Include key elements in the available database.
3)Develop a rapid screening method to search for the most promising compositions.
The candidate will work closely with the experimental platform development team to guide future trials and adapt the method to better meet the needs of large-scale production.