Nanostructuration de surfaces de silicium pour guider la croissance auto-organisée de nanostructures métalliques

Cette thèse porte sur le développement d'une méthode novatrice de réalisation de nanostructures. Offrant la possibilité de nanofabrication au delà des limites des techniques de lithogravure, la croissance auto-organisée, qui se caractérise par la formation spontanée d'îlots à partir d'atomes déposés en surface, fournit des nanostructures d'excellente qualité. L'idée de ce travail a été d'utiliser la structuration du substrat pour provoquer un arrangement périodique d'îlots nanométriques avec une faible dispersion en taille. Cette pré-structuration du substrat est obtenue de façon " naturelle " à partir des marches des surfaces vicinales et de façon " artificielle " en imposant un motif périodique par lithogravure. Nous avons élaboré des réseaux de trous sur des surfaces vicinales de Si par lithographie électronique et gravure ionique réactive. Une optimisation des conditions de lithogravure (plan d'expériences) ont permis de fabriquer des réseaux de trous de 40 nm espacés de 40 nm, avec un facteur de forme supérieur à 1. La structuration de surface se conclut par un recuit sous ultravide qui permet de réarranger la morphologie de celle-ci, notamment en ordonnant les marches suivant le réseau prédéfini par lithogravure. La formation de trous plus profonds et une hydrogénation de surface ont permis d'éviter que les trous ne disparaissent avant que la surface soit totalement réarrangée. En ajustant le flux d'atomes et la température, nous avons obtenu un alignement d'îlots d'Au le long des bords de marche de surfaces vicinales de Si avec des largeurs de terrasses équivalentes aux périodes des réseaux de trous. Ceci est un premier pas vers la croissance auto-organisée en 2D.The aim of this work is to obtain a very regular alignment of metallic nanostructures with high density and a narrow size distribution via a self-organised growth process. The method consists of combining microelectronic processes which will provide a periodic surface pattern, with self-assembled growth on the so-obtained surface. The structured surface serves as a template for the controlled positioning of the nanostructures. Concerning the silicon template preparation, the surface periodicity should be of the same order of magnitude as the atomic surface diffusion lengthused during subsequent growth. These surface patterns were obtained on vicinal silicon surfaces by optimising electron-beam nanolithography and reactive ion etching (design of experiments), to create arrays of nano-holes typically 40 nm in diameter with a 40 nm spacing. A subsequent sample annealing under ultrahigh vacuum conditions is studied in order to obtain a corrugated surface mimicking the lithography pattern. As a model system, the growth of Au on vicinal Si(111) surfaces has been chosen. After high temperature annealing, clean Si surfaces present arrays of straight step bunches each separated by 50 nm, the same scale as nano-holes array. We find the growth conditions to obtain the formation of Au islands on these step bunches edge. Theses conditions can be applied to naturally and artificially nanostructured surfaces to obtain self-organized growth of Au nanostructures.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Nanoparticules d'or fabriquées par lithographie par nanoimpression assistée UV et appliquées à la biodétection plasmonique

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Instrumentation multidimensionnelle pour la caractérisation d'interactions biomoléculaires sur surfaces structurées

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Low-cost SERS substrates composed of hybrid nanoskittles for a highly sensitive sensing of chemical molecules

International audienceIn this paper, we report on the low-cost and quick fabrication at the 4-in. wafer-scale of hybrid nanoskittles for a highly sensitive detection of chemical molecules. This quick and low-cost fabrication is achieved by using the native oxide layer as a physical etch mask coupled to an evaporation of a gold layer. The hybrid nanoskittles obtained with this technique are disordered on the 4-in. wafer of Si, and a good definition of nanoskittles and a good reproducibility of SERS signal are obtained on the whole wafer. Moreover, we studied experimentally the sensitivity of these Au/Si nanoskittles for SERS sensing. Finally, enhancement factors in the range of 10 7 − 1.1 × 10 8 were found for the detection of thiophenol molecules with hybrid nanoskittles

Proteomics Methodologies: The Search of Protein Biomarkers Using Microfluidic Systems Coupled to Mass Spectrometry

Protein biomarkers have been the subject of intensive studies as a target for disease diagnostics and monitoring. Indeed, biomarkers have been extensively used for personalized medicine. In biological samples, these biomarkers are most often present in low concentrations masked by a biologically complex proteome (e.g., blood) making their detection difficult. This complexity is further increased by the needs to detect proteoforms and proteome complexity such as the dynamic range of compound concentrations. The development of techniques that simultaneously pre-concentrate and identify low-abundance biomarkers in these proteomes constitutes an avant-garde approach to the early detection of pathologies. Chromatographic-based methods are widely used for protein separation, but these methods are not adapted for biomarker discovery, as they require complex sample handling due to the low biomarker concentration. Therefore, microfluidics devices have emerged as a technology to overcome these shortcomings. In terms of detection, mass spectrometry (MS) is the standard analytical tool given its high sensitivity and specificity. However, for MS, the biomarker must be introduced as pure as possible in order to avoid chemical noise and improve sensitivity. As a result, microfluidics coupled with MS has become increasingly popular in the field of biomarker discovery. This review will show the different approaches to protein enrichment using miniaturized devices and the importance of their coupling with MS

Combining SPRI and SERS with innovative nanostructured biochips (Orale)

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NanoBioForme - Surfaces hybrides nanostructurées et anisotropes pour la conception de capteurs biologiques plasmoniques sensibles à la conformation et à l'état d'organisation des biomolécules.

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Realization of nanostructures by soft UV nanoimprint lithography for biological applications

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Comparison between conventional and next generation lithography for bimodal SPRI-SERS biosensors

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Assembling, locating, grafting and actuating permanent magnetic filaments for validation of Polarimetric Surface Plasmon Resonance Imaging biosensors

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