Deterministic 3D self-assembly of Si through a rim-less and topology-preserving dewetting regime

Overview & Synopsis

Capillary-driven mass transport in solids is typically understood in terms of surface-diffusion limited kinetics, leading to conventional solid-state dewetting of thin films. However, another mass transport mechanism, so-called surface-attachment/detachment limited kinetics, is possible. It can shrink a solid film preserving its original topology without breaking it in isolated islands and leads to faster dynamics for smaller film curvature in contrast with the opposite behavior observed for surface-diffusion limited kinetics. In this work, we present a novel rimless dewetting regime for Si, which is ascribed to effective attachment-limited kinetics mediated by the coexistence of crystalline and amorphous Si phases. Phase-field numerical simulations quantitatively reproduce the experimental observations assessing the main mass transport mechanism at play. The process can be exploited to obtain in a deterministic fashion monocrystalline islands (with 95% probability) pinned at ∼500 nm from a hole milled within closed patches.