Electron Scattering at Epitaxial Ni(001) Surfaces

Epitaxial Ni(001) layers are sputter deposited on MgO(001) substrates and their electrical resistivity rho measured in situ as a function of thickness d(Ni) = 5-100 nm to quantify the resistivity size effect due to electron surface scattering. X-ray diffraction theta-2 theta scans, omega-rocking curves, and pole figures confirm an epitaxial layer-substrate relationshipwith Ni[001] parallel to MgO[001] and Ni[100] parallel to MgO[100]. The resistivity is well described with the semiclassical model by Fuchs and Sondheimer and a room-temperature bulk resistivity rho(o) = 7.04 mu Omega cm, yielding a bulk electron meanfree path lambda = 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 completelydiffuse electronsurface scattering. Allmeasured data are consistentwith a temperature-independentproduct rho(o)lambda = 18.3 x 10(-16) Omega m(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.