Crystallographic anisotropy of the resistivity size effect in single crystal tungsten nanowires

Abstract

This work demonstrates an anisotropic increase in resistivity with decreasing width in single crystal tungsten (W) nanowires having a height of 21 nm. Nanowire-widths were in the range of 15–451 nm, with the anisotropy observed for widths below 50 nm. The longitudinal directions of the nanowires coincided with the <100>, <110> and <111> orientations of the body centered cubic phase of W. The resistivity increase was observed to be minimized for the <111>-oriented single crystal nanowires, exhibiting a factor of two lower increase in resistivity at a width of ~15 nm, relative to the thin film resistivity (i.e., an infinitely wide wire). The observed anisotropy is attributed to crystallographic anisotropy of the Fermi velocity and the resultant anisotropy of the electron mean free path in W, and underscores the critical role of crystallographic orientation in nanoscale metallic conduction.

Surface roughness dependence of the electrical resistivity of W(001) layers

“…III, the comparison of in situ and ex situ resistivity measurements indicate no resistivity change during W surface oxidation. Therefore, both the W(001)-vacuum interface and the W(001)-WO 3 surface exhibit completely diffuse scattering, which is consistent with previous reports on W. 12,62 We attribute the diffuse scattering before air exposure to atomic-level surface defects, including adatoms, vacancies, and clusters, which cause a lateral perturbation of the flat surface potential drop, resulting in a destructive interference of the electron plane waves after reflection. 17,18 An additional independent argument for p ¼ 0 is based on the fact that data fitting with p ¼ 0 leads to relatively large k values of 33.0 6 0.4 and 37.6 6 0.5 nm, approximately double the isotropic value predicted from first principles.…”

“…We start in this discussion with the latter approach, primarily because the mean free path for tungsten is not well established, yet, with reported values varying considerably 42,44,60,61 and some reports suggesting that it may even be orientation dependent. 45,62 One convenient approach is to assume completely diffuse surface scattering, that is p ¼ 0. This assumption is correct for various systems including, for example, Cu exposed to air 18,63 or coated with Ta 64 or Ti, 34 and also provides a method to determine the lower bound for k, since less diffuse scattering would lead to a larger value for p which, in turn, results in a larger value for k. 60 Correspondingly, we first fit the measured room temperature resistivity data with the FS model using a fixed p ¼ 0, but allow different effective mean free paths for the two sets of samples.…”

Tunable Mechanical and Electrical Properties of Coaxial BN‐C Nanotubes

“…Comparison of the present data with the previous reports on different materials (Au, Ag, Cu, Al, Pt, and W nanowires, CNTs, BNNTs, and SiNW) in terms of elastic moduli and electrical resistivities at room temperature (different characteristic regions are marked).…”

Grain size effect on electrical resistivity of bulk nanograined Bi2Te3 material

“…Influence of the grain boundaries on the electrical resistivity can be taken into account in frames of the Mayadas-Shatzkes model [21,22]. According to this model, the grain boundaries can be regarded as potential barriers which have to be overcome by the electrons.…”