AVS 61st International Symposium & Exhibition
    Surface Science Wednesday Sessions
       Session SS+AS-WeM

Paper SS+AS-WeM1
Oxidation of Cu Surfaces with Step-Edge Defects: Insights from Reactive Force Field Simulation

Wednesday, November 12, 2014, 8:00 am, Room 312

Session: Atomistic Modeling of Surface Phenomena
Presenter: Qing Zhu, University of Pittsburgh
Authors: Q. Zhu, University of Pittsburgh
W.A. Saidi, University of Pittsburgh
J. Yang, University of Pittsburgh
Correspondent: Click to Email
Defects on metal surfaces can induce non-canonical oxidation channels that may lead to the formation of novel nanostructures. Cu surfaces have been actively researched in the surface science community due to their wide range of applications in many fields. Recently, in situ TEM experiments showed that the oxidation of stepped surfaces promotes the formation of a flat metal-oxide interface through the Cu adatoms detachment from steps and diffusion across the terraces. In order to better understand these results, and to provide a tight bridge between the experiment and theory, we have investigated the Cu (100) oxidation using ReaxFF method as implemented in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS). Using models for both defect-free flat and stepped surfaces, our study shows that the step-edge defects induce markedly different oxidation dynamical behavior compared to the flat surface. Additionally, on the stepped-surfaces, we show that the oxidation of the upper-terrace are more favored than the lower-terrace, which we validated by depositing oxygen homogenously on the surface or by using a biased-mechanism where the oxygen atoms target either the top or lower terraces. This favoring of the oxidation of the top terrace drives Cu diffusion flux from the upper-terrace to the lower-terrace that explains the recent TEM experiments. We additionally show that the oxidation behavior of the stepped Cu (100) bears many similarities with the formation of the metal-oxygen “added-row” structures on the (110) surfaces of several metals. Future studies include the investigation of vicinal surfaces with different morphologies and different metals.