arXiv subjects

A. W. Signor

Publications and source records attributed to A. W. Signor.

2 recordsLinked to original sources

arXiv2010

Misfit-Dislocation-Mediated Heteroepitaxial Island Diffusion

Scanning tunneling microscopy combined with molecular dynamics simulations reveal a dislocation-mediated island diffusion mechanism for Cu on Ag(111), a highly mismatched system. Cluster motion is tracked with atomic precision at multiple temperatures and diffusion barriers and prefactors are determined from direct measurements of hop rates. The non-monotonic size dependence of the diffusion barrier is in good agreement with simulations and can lead to enhanced mass transport upon coarsening, in surprising contrast to the traditional island diffusion models where diffusivity reduces with cluster size.

cond-mat.mtrl-sci↗

arXiv2009

Island Shape Controls Magic-Size Effect for Heteroepitaxial Diffusion

Lattice mismatch of Cu on Ag(111) produces fast diffusion for special "magic sizes" of islands. A size- and shape-dependent reptation mechanism is responsible for low diffusion barriers. Initiating the reptation mechanism requires a suitable island shape, a property not considered in previous studies of 1D island chains and 2D closed-shell islands. Shape determines the dominant diffusion mechanism and leads to multiple clearly identifiable magic-size trends for diffusion depending on the number of atoms whose bonds are shortened during diffusion.

cond-mat.mtrl-sci↗