Morphological transitions in Cu islands grown on strained Cu(100)*

A variety of experiments on submonolayer heteroepitaxial growth have demonstrated that the combined effects of strain and bonding can lead to shape transitions as well as dislocation formation. In order to separate out the effects of strain from “chemical” effects, we have used temperature-accelerated dynamics simulations to study a simple model system corresponding to the growth of Cu on a strained Cu(100) substrate. In the case of 2% compressive strain we find that - as previously found for Cu/Ni(100) growth [1] - multi-atom “pop-out” events are enhanced, leading to the formation of blobby islands with a mixture of open and closed step-edges. However, for much larger (4%) compressive strain, we find that island formation leads to the formation of dislocations. In contrast, dislocation formation does not occur in the absence of deposition. Finally, we find that - in good agreement with recent theoretical results [2] - a very large (8%) tensile strain leads to the formation of large anisotropic islands. The dependence of the barriers for monomer hopping and exchange on strain will also be discussed.
[1] Y. Shim and J.G. Amar, Phys. Rev. Lett. 108, 076102 (2012).
[2] J.G. Amar, Y. Shim, and R.T. Deck, Surf. Sci. 616, 120 (2013).