Gold colloidal nanoparticle electrodeposition on a silicon surface in a uniform electric field

The electrodeposition of gold colloidal nanoparticles on a silicon wafer in a uniform electric field is investigated using scanning electron microscopy and homemade electrochemical cells. Dense and uniform distributions of particles are obtained with no aggregation. The evolution of surface particle density is analyzed in relation to several parameters: applied voltage, electric field, exchanged charge. Electrical, chemical, and electrohydrodynamical parameters are taken into account in describing the electromigration process

Density multiplication of pores and their propagation in a thin layer of nanoporous alumina on silicon substrates

International audienceIn this work, perfectly organized triangular arrays of vertical nanopores are formed in an alumina matrix by combining a pre-patterning technique with the natural ability of alumina to form a triangular unit cell. More precisely, we imprinted a triangular array of indents on a thin layer of aluminum deposited on silicon substrates using nano-imprint lithography. During the anodization process, we forced the growth of pores in and in-between the indents obtaining a larger number of pores in the final alumina array than the initial number of indents patterned on the aluminum. Adapting the anodization conditions, a density multiplication by three was successfully achieved with a very good surface organization. The experimental details of the process are described in this paper. We studied in details the inner organization of the pores and we identified differences in their propagation between oxalic and orthophosphoric acid. The former showed a good surface propagation until 1500 nm in depth. On the contrary, the latter showed a perturbation in the organization at 450 nm: at this depth, the induced pores stopped whereas the indented ones rearranged into two or three. A longer shift in the initiation of the induced pores seemed to causes this poor propagation. A systematic study was performed to investigate the effect of the anodization conditions on the pores' propagation. We demonstrate that the optimization of the orthophosphoric acid concentration and the applied voltage towards harder anodization conditions, i.e. to higher values, allows a better control of this self-assembling process and deeper order propagation until more than 1000 nm. (C) 2015 Elsevier B.V. All rights reserved

Grazing Incidence X-ray Diffraction investigation of strains in silicon nanowires obtained by gold catalytic growth

International audienceIn this paper, we measure experimentally the strains in silicon nanowires using Grazing Incidence X-ray Diffraction. Silicon nanowires have been grown with a gold-catalytic method and have a crystalline character. Bragg's diffraction peak is measured and analyzed. A lattice mismatch parameter between the silicon substrate and silicon nanowires is found and accurately measured. The influence of the presence of the gold catalyst in the wires is investigated, and reveals a small decrease of the lattice mismatch parameter when the gold catalyst is removed. A residual strain is measured and a possible origin is proposed. An estimation of the surface and bulk stress is calculated and presented. (C) 2011 Elsevier B.V. All rights reserved

Structural investigation of nanoporous alumina film with grazing incidence small angle X-ray scattering

International audienceNanoporous alumina films (NPAF) have been elaborated by anodization of an aluminum film on silicon wafer. Ex situ structural characterization of the films has been achieved with grazing incidence small angle X-ray scattering under ultra high vacuum atmosphere and using a synchrotron source. The comparison of the experimental patterns with suitable modeling confirms the cylindrical geometry of the pores well as the good local hexagonal order. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinhei

Vertically Aligned Platinum Copper Nanotubes as PEM Fuel Cell Cathode: Elaboration and Fuel Cell Test

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Directed self-Assembled Porous Anodic Alumina as template for the CVD Growth of Silicon Nanowires

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