| Abstract
| - The spontaneous deposition process of Ni on Si(100) surface in aqueous alkaline solution was investigatedby electrochemical measurements and in situ attenuated total reflection Fourier transform infrared spectroscopy(ATR FTIR). The open circuit potential (OCP) profile revealed that the deposition reaction was self-terminatedas the potential steeply shifted in the positive direction after a certain immersion time. Auger depth profilesof specimens after the termination of the deposition reaction indicated that the surface was not completelycovered by Ni. To clarify the deposition behavior, anodic reaction of Si in an aqueous alkaline solutioncontaining no Ni ions was investigated by in situ ATR FTIR and electrochemical measurements. It wasfound that the deposition reaction was initiated by the formation of suboxide species of Si at the surface. Thissuboxide species served as “reductant” for Ni ions. Subsequently, the anodic reactions such as the oxidationof suboxide species and the anisotropic etching to 〈111〉 direction proceeded spontaneously. When 〈111〉oriented microfacets were formed, the surface was passivated with silicon dioxide. Because of the silicondioxide insulating properties, the electron generation by Si oxidation is inhibited, and then, the OCP sharplyshifted in the positive direction. Apparently, the formation of 〈111〉 oriented microfacets at the surface led tothe self-termination of the Ni deposition process. This study shows that the overall deposition reaction of Niis significantly affected by the anodic reaction of Si, including the oxidation and the anisotropic etching.
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