The electrodeposition of thin films of the element cobalt on silicon wafers opens the possibility of producing magnetic structures on top of a technological substrate using an efficient and inexpensive method. In this paper, we present an extensive study of the electrodeposition of Co on Si͑100͒ n-type substrates. Co thin films with metallic appearance and uniform thickness were obtained at deposition rates of 0.6 ͑2.8͒ nm/s for the 26 ͑104͒ mM Co electrolyte. A strong dependence of the surface roughness on the nucleation mechanism, i.e., instantaneous or progressive, was observed for layer thicknesses below 300 nm. Simultaneous magneto-optical Kerr effect and magnetoresistance measurements showed that magnetic behavior depends on the nucleation mechanism as well. Coercivity decays with increasing thickness, t, following a power law of the type t Ϫn , with n ϭ 1.6 ͑2.1͒ for the 26 ͑104͒ mM electrolyte, which reflects a strong dependence of the magnetic behavior on surface effects. A large variation of the in-plane coercive fields was observed for the 104 mM electrolyte, which varied from 730 to 13 Oe as film thickness increased from 26 to 260 nm.The electroplating technique is especially interesting due to its low cost, high throughput, and high quality of the deposits, being extensively used in the magnetic recording industry to deposit relatively thick Permalloy layers, for example. In this work, electrodeposition is used to prepare Co thin films on n-type Si substrates. The semiconducting substrates used conduct sufficiently well to allow electrodeposition without the need for a seed layer, leading to the integration of a convenient method for fabricating thin magnetic films and magnetic sensors with silicon technology.Different groups have already demonstrated the feasibility of direct electrodeposition of metallic layers on Si. 1-13 In particular, we draw attention to the fact that not much work has been done on the electrodeposition of Co layers on Si͑100͒. Continuous Co layers on Si with uniform thicknesses were obtained by Pasa and Schwarzacher. 6 The authors also describe the influence of hydrogen evolution as a function of deposition potential and cobalt sulfate concentration. More recently, Cerisier et al. 9 have reported on the structure and magnetic properties of Co films electrodeposited on Si͑100͒.In this paper we investigate in detail the deposition rate, current efficiency, as well as the evolution of surface roughness of Co thin films prepared under instantaneous and progressive nucleation mechanisms. Additionally, the simultaneous measurement of the surface magnetic hysteresis and magnetoresistance allowed us to obtain the dependence of the coercive field as a function of the thickness of the samples and concentration of the electrolytes. ExperimentalThe substrates used in our experiments were single side polished, technical grade ͑100͒-oriented Si wafers n-doped for a resistivity of 1-10 ⍀ cm. Electrical contact to each substrate was made through a GaAl back contact. An adhesive tape was used ...

Systematic measurements of giant magneto-impedance (GMI) and its relaxation (magneto-impedance aftereffect) have been carried out in a series of Co-rich amorphous ribbons ranging in magnetostriction values from −3.5 to +3.5 ppm. The value of GMI is a maximum for the alloy with the lowest value of magnetostriction, corresponding to a maximum of the transverse permeability. The impedance relaxation between two fixed times depends on the magnetostriction constant (λs) of the samples, and the observed trend is consistent with the theories which predict a direct relationship of the conventional permeability aftereffect (MAE) with the square of λs. Furthermore, the variation of the impedance aftereffect with the driving current resembles the behavior of MAE, and a connection between both effects can be established.

Thin films with the composition of the constantan alloy (a solid solution with 35 to 50 wt. % of Ni in Cu) have a high-thermoelectric power, which allows the fabrication of very sensitive heat-flux sensors based on planar technology. In this article, the thermoelectric properties of CuxNi100−x thin films electrodeposited on silicon were studied as a function of the composition, temperature, and thickness. The electrodeposition of thin layers on silicon is an important step for the integration of thermal sensors with semiconductor technology. The CuxNi100−x alloys were electrodeposited potentiostatically at room temperature, from a citrate electrolyte containing both copper and nickel sulfates. The layer composition was controlled by the applied potential in the range from pure copper (at −0.4 V/SCE) up to a solid solution of about 25 wt. % Cu in Ni (at −1.2 V/SCE). Extremely high values of thermoelectric power were measured for very thin layers of Cu40Ni60 on Si, showing a strong influence of the substrate. By considering the system as a thermoelectric bilayer and extracting the contribution of the semiconductor, thermopower values for the Cu40Ni60 alloys comparable to the expected ones for constantan wires were obtained.

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Cycloidal sector mass analyzers have, in principle, perfect focusing due to perpendicularly oriented uniform electric and magnetic fields, making them ideal candidates for incorporation of spatially coded apertures. We have previously demonstrated a proof-of-concept cycloidal-coded aperture miniature mass spectrometer (C-CAMMS) instrument and achieved a greater than 10-fold increase in throughput without sacrificing resolution, compared with a single slit instrument. However, artifacts were observed in the reconstructed mass spectrum due to nonuniformity in the electric field and misalignment of the detector and the ion source with the mass analyzer focal plane. In this work, we modified the mass analyzer design of the previous C-CAMMS instrument to improve electric field uniformity, improve the alignment of the ion source and the mass analyzer with the detector, and increase the depth-of-focus to further facilitate alignment. A comparison of reconstructed spectra of a mixture of dry air and toluene at different electric fields was performed using the improved C-CAMMS prototype. A reduction in reconstruction artifacts compared to our proof-of-concept C-CAMMS instrument highlights the improved performance enabled by the design changes.