We present in situ ultra-high vacuum measurements of the resistivity ρ of self-assembled endotaxial FeSi2 nanowires (NWs) on Si(110) using a variable-spacing two-point method with a moveable scanning tunneling microscope tip and fixed contact pad. The resistivity at room temperature was found to be nearly constant down to NW width W=4nm, but rose sharply to nearly double the bulk value at W=3nm. These data are not well-fit by a simple Fuch-Sondheimer model for boundary scattering, suggesting that other factors, possibly quantum effects, may be significant at the smallest dimensions. For a NW width of 4nm, partial oxidation increased ρ by approximately 50%, while cooling from 300K to 150K decreased ρ by approximately 10%. The relative insensitivity of ρ to NW size or oxidation or cooling is attributed to a high concentration of vacancies in the FeSi2 structure, with a correspondingly short length for inelastic electron scattering, which obscures boundary scattering except in the smallest NWs. It is remarkable that the vacancy concentration persists in very small structures.
ASJC Scopus subject areas
- Physics and Astronomy(all)