Ni silicide nanowires analysis by atom probe tomography

•Two methods of NW preparation have been proposed for NWs analysis by APT.•These methods were tested and reconstructed volumes for different kind of NWs.•Ni silicide formed on Si nanowire has been analyzed by atom probe tomography.•δ-Ni2Si is the only phase formed on Si NW and substrate after 200 °C during 1 h.•Au is localized at Ni/silicide interface after silicidation suggesting Ni diffusion.

The Ni silicide formed at low temperature on Si nanowire has been analyzed by atom probe tomography (APT) thanks to a special technique for sample preparation. A method of preparation has been developed using the focused ion beam (FIB) for the APT analysis of nanowires (NWs). This method allow for the measurement of the radial distribution when a NW is cut, buried in a protective metal matrix, and finally mounted on the APT support post. This method was used for phosphorous doped Si NWs with or without a silicide shell, and allows obtaining the concentration and distribution of chemical elements in three-dimensions (3D) in the radial direction of the NWs. The distribution of atoms in the NWs has been measured including dopants and Au contamination. These measurements show that δ-Ni2Si phase is formed on Si NW, Au is found as cluster at the Ni/δ-Ni2Si interface and P is segregated at the δ-Ni2Si/ Si NW interface. The results obtained on NWs after silicidation were compared with the silicide on the Si substrate, showing that the same silicide phase δ-Ni2Si formed in both cases (NWs and substrate).

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