| About this Abstract |
| Meeting |
2010 TMS Annual Meeting & Exhibition
|
| Symposium
|
Computational Thermodynamics and Kinetics
|
| Presentation Title |
Island Shape Controls Magic Size Effect for Heteroepitaxial Diffusion |
| Author(s) |
Henry H. Wu, Dallas R. Trinkle |
| On-Site Speaker (Planned) |
Henry H. Wu |
| Abstract Scope |
Low temperature in situ STM studies of Cu islands on Ag(111) by Weaver at UIUC observed anomalously fast diffusion for specific sizes of small monolayer islands (magic size effect). To computationally study the dynamics of Cu island diffusion, we use ultrasoft pseudo-potential GGA calculations to optimize an embedded atom method (EAM) potential. The optimized EAM calculates diffusion barriers of Cu islands up to 14-atoms. Previous work by Hamilton for 1D and 2D heteroepitaxial island diffusion found a magic size effect associated with collective glide dislocation-mediated mechanism. For Cu/Ag(111) we find---in addition to collective glide---lower diffusion barriers for the reptation dislocation-mediated mechanism. The reptation mechanism is limited by bond-breaking considerations that result from the 2D island shape. By grouping islands according to the number of [110] rows affected by the diffusion dislocation, the 2D diffusion barriers follow trends seen in the 1D magic size effect. |
| Proceedings Inclusion? |
Definite: A CD-only volume |