DENDRITIC ISLANDS IN METAL-ON-METAL EPITAXY .2. COALESCENCE AND MULTILAYER GROWTH

Dendritic or fractal islands occur naturally during epitaxial growth in systems where island edge diffusion is restricted. Here we use a lattice-gas model to characterize the evolution of island structure in such systems, from the low coverage to the coalescence regime, and to consider the ramifications for multilayer growth. Island densification and slowing of radial growth prior to coalescence is observed in the simulations, as in Au/Ru(0001). We also elucidate the relationship of the real-space island structure to the width and shape of the corresponding kinematic diffraction profile. Our multilayer growth studies incorporate disruption of and downward funneling from island edges upon impact of depositing atoms, in the presence of a large Schwoebel barrier. Using the geometry and length scales appropriate for Pt/Pt(111), the calculated kinematic Bragg intensities for a two-layer model show that even limited disruption can produce the observed low-temperature ''reentrant'' oscillations.