PREPARATION OF NI NANOPARTICLES MONO-LAYER ON POLYIMIDE SUBSTRATE

Abstract

In order to demonstrate that the exposed Ni nanoparticles can be used as a template for growing nano-sized structures, atomic layer deposition was used to deposit ~5-nm-thick film of Co on top of the nanoparticles. As can be seen Fig. 2, the Co film, instead of forming a continuous film, broke apart into discrete islands whose size approximately matches that of the Ni particles on the template. It appears that the Ni particles on the substrate provided sites on which Co preferentially nucleated and grew. The inset in Fig. 2, showing the cross-sectional TEM image of the Co film, clearly attests to the fact that the Co grains grew aligned to the Ni seeds. Prior to the Co deposition, the Ni nanoparticles were weakly ferromagnetic with near-zero coercivity due to the oxidation of both Ni and Fe. However, after the Co deposition, the saturation magnetization markedly rose and the coercivity increased to 25 Oe.