Pushing the limits of capillary assembly for the arbitrary positioning of sub-50nm nanocubes in printable plasmonic surfaces

Anna Capitaine (1, 2) , Muhammad Fajri , Beniamino Sciacca (1, 2)

1 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille
2 AMU SCI - Aix-Marseille Université - Faculté des Sciences

The fabrication of high quality nanophotonic surfaces for integration in optoelectronic devices remains a challenge because of the complexity and cost of top-down nanofabrication strategies. Combining colloidal synthesis with templated self-assembly emerged as an appealing low-cost solution. However, it still faces several obstacles before integration in devices can become a reality. This is mostly due to the di culty in assembling small nanoparticles (<50 nm) in complex nanopatterns with a high yield. In this study, we propose a reliable methodology to fabricate printable nanopatterns with an aspect ratio varying from 1 to 10 and a lateral resolution of 30 nm via nanocube assembly and epitaxy. Investigating templated assembly via capillary forces, we identified a new regime that we used to assemble 30 to 40 nm nanocubes in a patterned PDMS template with a high yield for both Au and Ag with multiple particles per trap. This new method relies on the generation and control of an accumulation zone at the contact line that is thin as opposed to dense, displaying higher versatility. This is in contrast with conventional wisdom, identifying a dense accumulation zone as a requirement for high-yield assembly. In addition, we propose di↵erent formulations that can be used for the colloidal dispersion, showing that the standard water-surfactant solutions can be replaced by surfactant-free ethanol solutions, with good assembly yield. This allows to minimize the presence of surfactants that could a↵ect electronic properties. Finally, we show that the obtained nanocube arrays can be transformed into continuous monocrystalline nanopatterns via nanocube epitaxy at near ambient temperature, and transferred to di↵erent substrates via contact printing. This approach opens new doors to the templated assembly of small colloids and could find potential applications in various optoelectronic devices ranging from solar cells to light-emitting diodes and displays.

Mots clés: Capillary assembly; bottom-up; nanocube; epitaxy; welding; plasmonic metasurface

Domaines: Micro et nanotechnologies/Microélectronique; Chimie théorique et/ou physique

Anna Capitaine, Muhammad Fajri, Beniamino Sciacca. Pushing the limits of capillary assembly for the arbitrary positioning of sub-50nm nanocubes in printable plasmonic surfaces. Small Methods, 2023, ⟨10.1002/smtd.202300373⟩. ⟨hal-04129724⟩