Gaël Gautier

Bio: Gaël Gautier is an academic researcher from François Rabelais University. The author has contributed to research in topics: Silicon & Porous silicon. The author has an hindex of 18, co-authored 98 publications receiving 946 citations. Previous affiliations of Gaël Gautier include University of Rennes & Centre national de la recherche scientifique.

Investigations on porous silicon as electrode material in electrochemical capacitors

Abstract: In this study, we have demonstrated the possibility of using macroporous silicon electrodes in electrochemical capacitors. Macroporous silicon was used to increase the surface exchange between pore surface and electrolyte. The inherent resistivity of the porous silicon can be reduced through the use of subsequent doping and metallization processes of the macropore surface. A systematic study of the electrolyte concentration and the porous silicon depth influences was also performed. A unit cell capacitance value of 320 µF/cm2 was obtained with doped and metallized p-type macroporous silicon electrodes. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Enhanced quantum yield of photoluminescent porous silicon prepared by supercritical drying

Abstract: The effect of supercritical drying (SCD) on the preparation of porous silicon (pSi) powders has been investigated in terms of photoluminescence (PL) efficiency. Since the pSi contains closely spaced and possibly interconnected Si nanocrystals (<5 nm), pore collapse and morphological changes within the nanocrystalline structure after common drying processes can affect PL efficiency. We report the highly beneficial effects of using SCD for preparation of photoluminescent pSi powders. Significantly higher surface areas and pore volumes have been realized by utilizing SCD (with CO2 solvent) instead of air-drying. Correspondingly, the pSi powders better retain the porous structure and the nano-sized silicon grains, thus minimizing the formation of non-radiative defects during liquid evaporation (air drying). The SCD process also minimizes capillary-stress induced contact of neighboring nanocrystals, resulting in lower exciton migration levels within the network. A significant enhancement of the PL quantum yiel...

Porous silicon for electrical isolation in radio frequency devices: A review

Abstract: The increasing expansion of telecommunication applications leads to the integration of complete system-on-chip associating analog and digital processing units. Besides, the passive elements occupy an increasing silicon footprint, compromising circuit scalability and cost. Moreover, passive components’ performances are limited by the proximity of lossy Si substrate and surrounding metallization. Then, obviously, the characteristics of the substrate become crucial for monolithic radio frequency (RF) systems to reach high performances. So, looking for integrated circuit compatible processes, porous silicon (PS) seems to be a promising candidate as it can provide localized isolating regions from various silicon substrates. In this review, we first present all the possible porous silicon substrates, which can be used for RF devices. In particular, we put the emphasis on the etching conditions, leading to high thickness localized PS layers. The intrinsic electrical properties of porous silicon such as AC electrical conductivity or dielectric constant are also detailed, and the results extracted from the literature are commented. Then, we describe the performances of widespread RF devices, that is, inductors or coplanar waveguides. Finally, we describe methodologies used for predicting RF electrical responses of PS isolated devices, based on electromagnetic simulations.

Plasma-deposited fluoropolymer film mask for local porous silicon formation

Abstract: The study of an innovative fluoropolymer masking layer for silicon anodization is proposed. Due to its high chemical resistance to hydrofluoric acid even under anodic bias, this thin film deposited by plasma has allowed the formation of deep porous silicon regions patterned on the silicon wafer. Unlike most of other masks, fluoropolymer removal after electrochemical etching is rapid and does not alter the porous layer. Local porous regions were thus fabricated both in p+-type and low-doped n-type silicon substrates.

Principles Of Fluorescence Spectroscopy

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Damascene copper electroplating for chip interconnections

Abstract: Damascene copper electroplating for on-chip interconnections, a process that we conceived and developed in the early 1990s, makes it possible to fill submicron trenches and vias with copper without creating a void or a seam and has thus proven superior to other technologies of copper deposition. We discuss here the relationship of additives in the plating bath to superfilling, the phenomenon that results in superconformal coverage, and we present a numerical model which accounts for the experimentally observed profile evolution of the plated metal.

Durability Investigation of Carbon Nanotube as Catalyst Support for Proton Exchange Membrane Fuel Cell Electrode

Abstract: Abstract Electrochemical surface oxidation of carbon black Vulcan XC-72 and multiwalled carbon nanotube (MWNT) has been compared following potentiostatic treatments up to 168 h under condition simulating PEMFC cathode environment (60 °C, N2 purged 0.5 M H2SO4, and a constant potential of 0.9 V). The subsequent electrochemical characterization at different treatment time intervals suggests that MWNT is electrochemically more stable than Vulcan XC-72 with less surface oxide formation and 30% lower corrosion current under the investigated condition. As a result of high corrosion resistance, MWNT shows lower loss of Pt surface area and oxygen reduction reaction activity when used as fuel cell catalyst support.