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Fe–Pd alloy films have been prepared by electrochemical deposition from an alkaline electrolyte containing Fe sulfate, Pd chloride and 5-sulfosalicylic acid onto polycrystalline titanium substrates. The as-deposited films were nanocrystalline and magnetically soft (coercivity ∼ 25 Oe). L10 Fe–Pd films with a (1 1 1) preferred orientation were obtained by post-deposition thermal annealing of films with composition about 37 at% Fe in an (Ar + 5% H2) gas flow at 500 °C. Such films exhibit hard magnetic properties, with a coercivity up to 1880 Oe, and a slightly anisotropic magnetic response, with a larger in-plane remanence. Preliminary magnetic investigations support magnetization switching through pinning of domain walls. Keywords: Fe–Pd, Electrodeposition, L10

Adherent copper films were electrochemically grown onto the native oxide surfaces of Si wafers modified by the adsorption of polyamidoamine (PAMAM) dendrimers. Metallic nuclei of copper grow at isolated nucleation sites, associated with adsorbed dendrimers, and film coalescence can be observed above a metal thickness of about 10,000 monolayers (∼2.5 μm). Film microstructure depends on the deposition mode; higher coverage and better adhesion were obtained by galvanostatic control of the deposition process. It is hypothesized that reduction of Cu2+ ions complexed with functional groups of the chemisorbed dendrimer leads to the formation of metallic copper nuclei, and that metal films grow from these nuclei. Further improvement of this process may open the way to the direct integration of metal electrodeposition with silicon microfabrication processes and selective deposition by dendrimer patterning.

Electrochemical deposition of materials with hard magnetic properties in the as-deposited state is essential for the efficient integration of micro-magnetic components into MEMS devices. Here we discuss the growth process and the microstructure-magnetic properties correlation for two Co-rich alloys, Co–Ni–P and Co–Pt. Under suitable synthesis conditions, these materials exhibit perpendicular anisotropy and hard magnetic properties in the as-deposited state; in addition, such properties are maintained up to several micrometer film thickness through close control of the film microstructure. In the case of Co–Ni–P films we achieved a saturation magnetization of 1.21 T (963 emu/cm 3 ), perpendicular coercivity up to 188 kA/m (2.36 kOe) at a thickness of 10 μm, and energy products up to 4.2 kJ/m 3 . Co-rich Co–Pt films were grown on several substrates – Cr, Cu(0 0 1), Cu(1 1 1), and Ru(0 0 0 1) – in order to control magnetic anisotropy and achieve optimum hard magnetic properties. Cu(1 1 1) contributes to stabilize the hexagonal hcp phase at high current density yielding excellent hard magnetic properties, although only in films thicker than 100 nm; saturation magnetization in these films was about 1.04 T (828 emu/cm 3 ). Perpendicular coercivities up to 485.6 kA/m (6.1 kOe) were obtained in 1 μm thick film deposited at 50 mA/cm 2 . Ru(0 0 0 1) seed layers provide an appropriate interface structure to further facilitate the epitaxial growth of hcp films, yielding hard magnetic properties and perpendicular coercivity with a squareness ∼1 in films as thin as 10 nm. The hard magnetic properties were only marginally compromised at large film thickness. Deposition at higher current density (50 mA/cm 2 ) favored markedly improved hard magnetic properties. The Co–Pt films on Ru exhibited perpendicular anisotropy with anisotropy constant up to 1.2 MJ/m 3 . The electrodeposition process was further extended to fill lithographically patterned hole arrays (850 nm diameter, center-to-center distance 2550 nm and about 700 nm thick resist), yielding arrays of micron-sized hard magnetic cylinders with perpendicular coercivity of 361 kA/m (4.54 kOe) and high squareness.

The electrochemical nucleation and growth of Au from a Au sulfite electrolyte onto dodecanethiol-modified Au surfaces is investigated by a combination of microscopy and chronoamperometry methods. The self-assembled dodecanethiol monolayers are continuous but exhibit defects in correspondence of the Au grain boundaries and on top of Au terraces. Nucleation of Au films occurs initially at these defect sites, but only a small fraction of these nuclei survive an initial competition process. The remaining nuclei expand through three-dimensional progressive nucleation followed by diffusion-limited growth. The resulting Au films exhibit microstructures which are widely different from those observed in the electrochemical growth of Au on Au and that depend on the applied potential: while at low overpotentials the film grows as an assembly of hemispherical clusters, at intermediate overvoltages the films are smooth and at high overvoltages become dendritic. Metal growth onto self-assembled monolayer-modified substrates can thus provide an alternative method for controlling film morphology for a wide range of applications.

We report on the synthesis and characterization of nanofibrous structures of vanadium oxide V 2 O 5 by anodic electrodeposition. The electrodeposits are thick layers of several micrometers consisting of fibers with length in the micrometer range and a width of about 10 nm. At variance with available reports, the vanadium oxide nanofibers were obtained without the use of templates or additives. Electrochemical synthesis was performed in aqueous solutions containing VOSO 4 and Na 2 SO 4 . The observed sponge-like structure, and consequent large surface area, with strong entanglement of the nanofibers are potentially important material ' features for applications such as gas sensors, lithium batteries, and catalysis.

We investigate the influence of chloride Cl - ions in a broad range of chloride concentrations on the kinetics and mechanism of copper electrodeposition from sulfate-based acidic electrolytes. Chloride ions influence copper deposition through two competitive effects: at low Cl - concentration (few mM), chloride ions depolarize the Cu reduction process, while higher Cl - concentrations induce complexation of copper species and cause a cathodic polarization of the deposition process. Cu reduction proceeds through two parallel mechanisms, a direct two-step reduction and a chloride-mediated route, whose relative importance depends on the amount of chloride present. A transition between these two mechanisms can be identified both by steady-state and impedance methods; however, the chloride concentration at which it occurs depends on the time scale probed by the two techniques. Impedance measurements further demonstrate that the presence of chlorides changes the double-layer structure.

We present a study of the effect of chloride anion additions on the electrochemical nucleation and growth of copper on n-Si(100) from acidic sulfate solutions. Chloride additions in the millimolar range depolarize copper reduction, while additions in the 100 mM range and above have the opposite effect. Chlorides have no effect on the nucleation and growth mode. Deposition at constant potential in the presence of small amounts of chloride leads to an increased deposition overpotential, but contrary to the predictions of nucleation theory, this results in a lower density of nuclei with larger size. We hypothesize that adsorption of chlorides on the copper islands enhances surface diffusion processes which lead to island coarsening through Ostwald ripening. Morphological changes during deposition are possible at room temperature due to the high values of diffusivities at the electrolyte/ solid interface.

CoNiP alloy films have been grown by electrodeposition from a chloride bath under galvanostatic control. Film growth, structure, composition, magnetic properties, and morphology have been found to depend significantly on deposition current density. Hard magnetic films were successfully grown at the current density of 7 mA/cm 2 with thickness up to 10 μm, at which a perpendicular coercivity of 188 kA/m was achieved. The magnetic hardness and perpendicular anisotropy of these films are the combined result of a microstructure composed of columnar grains and of a hexagonal phase oriented with the c axis perpendicular to the film plane. Preliminary investigations of magnetization reversal processes suggest the presence of pinning sites located probably at grain boundaries.

Co-Pt (Pt ∼ 20 atom %) alloy films were electrochemically grown at constant current density on Cr seed layers in order to study the influence of the Cr surface on their morphology and magnetic properties. The Cr seed layer favors the growth of a hexagonal close-packed phase, as revealed by X-ray diffraction. Morphological investigation using a scanning electron microscope revealed the electrocrystallization of Co-Pt on Cr to be proceeding through the nucleation and growth of three-dimensional (3D) clusters with columns growing outward in all directions from isolated nucleation centers. The 3D growth is likely due to the presence of a thin oxide layer on the Cr seed. At lower current density, individual micrometer-sized clusters were formed with distinct hexagonally shaped faces. Increasing current density results in a finer grain microstructure. At early stages of growth and low current density, the clusters exhibit a faceted morphology similar to that of the substrate. Samples prepared at higher current density or with larger thickness show larger coercivities, reaching values as high as 3490 Oe (278 kA/m) and 2275 Oe (181 kA/m) in the perpendicular and parallel directions, respectively, for a 500-nm-thick film deposited at 50 mA/cm 2 .