Influence of misfit dislocations on nanoisland decay

Abstract

We investigate the decay of Ag islands on Cu(111) by variable low temperature scanning tunneling microscopy between 195 and 250 K. Such islands exhibit a misfit dislocation pattern forming $(8\ifmmode\times\else\texttimes\fi{}8)$ to $(10\ifmmode\times\else\texttimes\fi{}10)$ superstructures because of a major lattice mismatch between silver and copper. The decay of islands smaller than $200{\mathrm{nm}}^{2}$ alternates between a slower and a faster decay. It is slower for specific island sizes, in particular those with magic numbers of superstructure unit cells. We relate these changes to the complexity of the heteroepitaxial decay, involving a deconstruction of the misfit dislocation pattern and a simultaneous diffusion of several adspecies during decay.