Nanoscale topographical control of capillary assembly of nanoparticles

• Published in: Nature nanotechnology Vol. 12; no. 1; pp. 73 - 80
• Main Authors: Flauraud, Valentin, Mastrangeli, Massimo, Bernasconi, Gabriel D., Butet, Jeremy, Alexander, Duncan T. L., Shahrabi, Elmira, Martin, Olivier J. F., Brugger, Juergen
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2017; Nature Publishing Group
• Subjects: 142/126; 147/135; 147/137; 147/143; 147/28; 639/624/399/354; 639/925/927; Assembly; Gold; Harnesses; Insertion; Laboratories; Materials Science; Nanoparticles; Nanorods; Nanostructure; Nanotechnology; Nanotechnology and Microengineering; Solvents; Substrates; Topography; Switzerland
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/nnano.2016.179

Predetermined and selective placement of nanoparticles onto large-area substrates with nanometre-scale precision is essential to harness the unique properties of nanoparticle assemblies, in particular for functional optical and electro-optical nanodevices. Unfortunately, such high spatial organization is currently beyond the reach of top-down nanofabrication techniques alone. Here, we demonstrate that topographic features comprising lithographed funnelled traps and auxiliary sidewalls on a solid substrate can deterministically direct the capillary assembly of Au nanorods to attain simultaneous control of position, orientation and interparticle distance at the nanometre level. We report up to 100% assembly yield over centimetre-scale substrates. We achieve this by optimizing the three sequential stages of capillary nanoparticle assembly: insertion of nanorods into the traps, resilience against the receding suspension front and drying of the residual solvent. Finally, using electron energy-loss spectroscopy we characterize the spectral response and near-field properties of spatially programmable Au nanorod dimers, highlighting the opportunities for precise tunability of the plasmonic modes in larger assemblies. Gold nanorods can be placed with nanometric control of position, orientation and interparticle distance over centimetre-scale areas.