Specular electron scattering at single-crystal Cu„001... surfaces

Epitaxial copper layers, 20 nm to 1.5m-thick, were grown on MgO 001 by ultrahigh vacuum magnetron sputter deposition at 80 °C. In situ electrical resistivity measurements indicate partial specular scattering at the Cu vacuum interface with a Fuchs–Sondheimer scattering parameter p =0.6 0.1. In situ deposition of 0.3 to 7.0-nm-thick Ta cap layers on the Cu surfaces leads to a resistivity increase, which is independent of the Ta thickness and is associated with a transition to completely diffuse surface scattering with p=0.0 0.1. The diffuse scattering is attributed to a “rough” electron potential at the Cu–Ta interface as well as to scattering into localized interface and surface states. © 2009 American Institute of Physics. DOI: 10.1063/1.3157271