Dresden 2011 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 80: Epitaxy and growth: Metals and semiconductors I

O 80.2: Vortrag

Donnerstag, 17. März 2011, 15:15–15:30, WIL C307

Anion-enhanced self-diffusion on Au(100) — •Mostafa Mesgar, Payam Kaghazchi, and Timo Jacob — Institut für Elektrochemie, Universitüt Ulm, Albert-Einstein-Allee 47, 89069 Ulm

Surface phenomena, such as thin film growth, corrosion and crystal growth, are determined by the diffusion of atoms on surfaces. Although several experimental and theoretical studies already focused on the adatom diffusion, much less is known about how possible co-adsorbates might influence diffusion barriers or even migration mechanisms, which could lead to modifications in the surface morphology. Performing large-scale density functional theory (DFT) studies we have investigated the anion-modified self-diffusion on Au(100). We investigated the adsorption and various migration mechanisms of Au atoms on clean [1] and Cl-covered Au(100) with and without surface defects (e.g. steps, kinks, or vacancies). Our studies indicate that in both systems (i.e. clean and Cl-covered) the exchange mechanism, is the most favorable mechanism. Further, we find that for all diffusion processes the presence of co-adsorbed Cl decreases the diffusion barriers, which should result in faster Ostwald ripening. Based on our DFT results the next aim will be to generate a reactive forcefield for Au-Au and Au-Cl interactions,[2] which coupled with kinetic Monte-Carlo will allow for large-scale simulations, providing macroscopic quantities (e.g. diffusion coefficients) readily comparable to experiments.

1. K. Pötting, W. Schmickler, T. Jacob, Chem. Phys. Chem., 11, 1395 (2010). 2. D. Fantauzzi, J. A. Keith, A. C. T. van Duin, T. Jacob, Phys. Rev. B, 81, 235404 (2010).