Electrically robust ultralong nanowires of NiSi, Ni2Si, and Ni31Si12

Abstract
Mass fabrication of directly accessible, ultralong, uniform Si nanowires is realized by employing a controllable and reproducible method based on standard Si technology. High-conductivity polycrystalline Ni-silicide nanowires around 30 nm by 30 nm in cross section, able to support extremely high currents at ∼108A∕cm2, are obtained by means of solid-state reaction of the Si nanowires with subsequently deposited Ni films. By properly adjusting the Ni film thickness, NiSi, Ni2Si, and Ni31Si12 nanowires characterized with distinct resistivity and temperature coefficient of resistance are obtained. Upon annealing, the electrical continuity of the nanowires breaks at temperatures about 0.7 times the melting points of the silicides.