Electron scattering at single crystal Cu surfaces

Epitaxial copper layers, 6.6 nm to 1.2 μm thick, were grown on MgO(001) by ultra-high vacuum magnetron sputter deposition at 100 °C. The surface morphology, as determined by in-situ scanning tunneling microscopy, exhibits a regular mound structure. The mounds grow in width w and height h as a function of layer thickness t from h = 3 nm and w = 20 nm for t = 20 nm to h = 5 nm and w = 200 nm for t = 1.2 μm. The resistivity increases with decreasing layer thickness from 1.70 μΩ-cm for t = 1.2 μm to 8.35 μΩ-cm for t = 6.6 nm. The resistivity increase is consistent with the Fuchs–Sondheimer model for completely diffuse surface scattering. The diffuse scattering is attributed to a high density of surface steps, which are separated by less than 1 nm.