Fabrication of 3D nanostructures via concave-corner-mediated lateral growth process
Mu Wang
American Physical Society & Nanjing University

Future information technology relies on our capability to fabricate microstructures of functional materials. The fabrication methods can usually be categorized into top-down lithography and bottom-up self-organization. The top-down approach has unprecedented accuracy and controllability, yet requires sophisticated equipment and expensive operating costs. The bottom-up approach, on the contrary, is cost-efficient and does not rely on sophisticated facilities. However, self-organization lacks strict repeatability and spatial homogeneity over a large area. Here I present an unexpected approach of electrochemical growth of ordered metallic nanowire arrays from an ultrathin electrolyte layer, which is achieved by solidifying the electrolyte solution below the freezing temperature. The thickness of the electrodeposit is instantaneously tunable by the applied electric pulses, leading to parallel ridges on webbed film without using any template. An array of metallic nanowires with desired separation and width determined by the applied electric pulses is formed on the substrate with arbitrary surface patterns by etching away the webbed film thereafter. This work demonstrates a previously unrecognized fabrication strategy that bridges the gap between top-down lithography and bottom-up self-organization in making ordered metallic nanowire arrays over a large area at a very low cost.

References:
1. Formation of magnetic nanowire arrays by cooperative lateral growth, Science Advances, 8, eabk0180 (2022)
2. Construction of 3D metallic nanostructures on an arbitrarily shaped substrate, Advanced Materials 28, 7193 (2016)
3. Periodic magnetic domains in single-crystalline cobalt filament arrays, Physical Review B 93, 054405 (2016)