Grain-boundary and surface scattering are known to increase the electrical
resistivity of thin metallic films and wires. The length scale at which the
se produce appreciable effects is of the order of the electronic mean free
path. For the well-studied case of thin films, both mechanisms can, in prin
ciple, be used to explain the observed thickness dependence on resistivity.
In order to evaluate which of these mechanisms is more relevant, we have c
arried out an experimental study of the width dependence of the resistivity
of narrow thin-film polycrystalline gold wires (nanowires), and computed t
he expected behavior on the basis of both surface and grain-boundary scatte
ring mechanisms independently. We find that the resistivity increases as wi
re width decreases in a manner which is dependent on the mean grain size an
d cannot be explained adequately by either model alone. We propose a modifi
cation to the well-known model of Mayadas and Shatzkes, incorporating the v
ariation of mean grain size on wire dimensions.