Characterization of Permalloy thin films electrodeposited on Si(111) surfaces

The electrochemical conditions for the direct electroplating of Ni–Fe Permalloy (19% Fe, 81% Ni) thin films onto Si(111) surfaces were determined. The film composition, structure, and magnetic properties were examined by various techniques involving Auger electron spectroscopy depth profiles analysis, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and magneto-optic Kerr effect measurements. The Permalloy films consisted of 10–50-nm-diam Ni/Fe nanocrystallites. It was found that the coercivity decreased with increased film thickness. Moderate annealing of the films below 200 °C released stress in the films and led to a decrease in coercivity. Interfacial diffusion occurred after the annealing of films above 300 °C. The Ni–Fe films exhibited bulk properties after the completion of electrodeposition of a buffer layer of thickness >20 nm; below this thickness, the films were discontinuous and consisted of separated clusters or islands on the Si surface.