Division of Engineering
Self-assembly and shape transitions of epitaxial nanowires and strained monolayer islands
Several interesting shape transitions have been recently observed during the growth of submonolayer islands on lattice-mismatched substrates. These shapes, which allow relaxation of mismatch strain, include nanowires that are elongated along certain crystallographic directions with widths in the single-digit nanometer range, shapes that show concave boundaries in equilibrium and formation of highly ramified or branched structures during growth. In this talk, I will present a sharp interface model and a phase-field model to study the shapes (kinetic and equilibrium) of individual islands and stability and coarsening kinetics of monolayer island arrays. Our model includes the kinetics of adatom diffusion on the terraces and island edges, attachment kinetics to islands, substrate-mediated elastic interactions between the islands and anisotropies associated with the creation of island edges. Particular emphasis will be given to self-assembled growth of regular arrays of epitaxial nanowires that have potential applications as non-lithographically fabricated interconnects.