Evolution of hierarchically-layered Cu-rich silicide nano-architectures

A solution based synthesis of well-ordered Cu-rich silicide nanoarchitectures, consisting of a pair of layered cups and stems (ρ-Cu₁₅Si₄) is demonstrated. The as-grown ρ-Cu₁₅Si₄ typically exhibits distinct interconnected 1D stems, consisting of a stack of nanorods (∼300 nm in length), terminated with concave hexagonal 3D cups that evolve through a self-regulated layer-by-layer growth mechanism. Discrete-time ex situ experimental observations reveal that the ρ-Cu₁₅Si₄ evolution is driven by interatomic diffusion, initially triggering the formation of binary-phase silicide islands (spheres) followed by the formation of hexagonal discs, stem growth, and lateral elongation in exactly opposite directions. It is further shown that electrochemically pregrown Cu-crystals can facilitate the direct growth of ρ-Cu₁₅Si₄ in high yield with enhanced substrate coverage.