Growth of branching Si nanowires seeded by Au-Si surface migration

Gold-silicon eutectic liquid surface migration is employed during an intermediate annealing to synthesize branched silicon nanowires by the vapor-liquid-solid (VLS) mechanism without additional gold seeding steps. Independent control of primary nanowire and branch length is demonstrated. Scanning electron micrographs confirm the unkinked nature of the branches, and show that the presence of hydrogen during the annealing is crucial for the growth of long, single-crystalline Si branches. Scanning confocal Raman microscopic maps indicate the high crystallinity of the branched nanowires, while transmission electron microscopy studies demonstrate the epitaxial growth of the branches and confirm their [(1) over bar 11] growth direction. This strategy is versatile in that it may be extended to many materials, individually or in combination, available for VLS grown nanowires for the synthesis of tailored, hierarchical nanostructures with fundamentally novel and technologically relevant properties.