Electron Scattering at Epitaxial Ni(001) Surfaces

Epitaxial Ni(001) layers are sputter deposited on MgO(001) substrates and their electrical resistivity p measured in situ as a function of thickness dNi = 5-100 nm to quantify the resistivity size effect due to electron surface scattering. X-ray diffraction 8-28 scans, w-rocking curves, and pole figures confirm an epitaxial layer-substrate relationship with Ni[001]II MgO[001] and Ni[100]II MgO[100]. The resistivity is well described with the semiclassical model by Fuchs and Sondheimer and a room-temperature bulk resistivity p
_o
= 7.04 μΩ cm, yielding a bulk electron mean-free path λ = 26 ± 2 and 350 ± 20 nm at 295 and 77 K, respectively. Air exposure causes a resistivity increase by up to 21%, which is attributed to monolayer surface oxidation that results in a transition from 30% specular to completely diffuse electron surface scattering. All measured data are consistent with a temperature-independentproduct po
_λ
= 18.3 × 10
^-16
Ωm
²
, which is 4.5 times larger than previously predicted from first-principles, indicating that Ni is less promising as a metal for narrow interconnect lines than those predictions suggest.