Effect of O_2 adsorption on electron scattering at Cu(001) surfaces

摘要

The electrical resistance of epitaxial Cu(001) sequentially increases, decreases, and again increases when exposed to 10~(-3)-10~5 Pa s of O_2. This is attributed to partial specular surface scattering for smooth clean Cu(001) and for the surface with a complete adsorbed monolayer, but diffuse scattering at partial coverage and after chemical oxidation. A model relates the surface coverage to the specularity parameter and finds adatom and advacancy scattering cross-sections of 0.8 ± 0.2 and 0.06 ±0.03 nm~2, which are qualitatively validated by nonequilibrium ab initio transport simulations. The rates for resistance change are proportional to the O_2 partial pressure.