Dendritic islands in metal-on-metal epitaxy I. Shape transitions and diffusion at island edges

Abstract The development of dendritic island shape instabilities observed during metal-on-metal epitaxy is investigated via a lattice-gas model for the low coverage regime. The key assumption is that island structure is controlled by the competition between shape equilibration due to adatom edge diffusion, and Mullins-Sekerka-type shape instability due to diffusion-limited aggregation of adatoms with islands. From comparison with scanning tunneling microscopy data (for the island density and average width of dendritic arms), we advance estimates of the energy barrier for edge diffusion in several systems.