Moiré Nanosphere Lithography

Abstract

We have developed moiré nanosphere lithography (M-NSL), which incorporates in-plane rotation between neighboring monolayers, to extend the patterning capability of conventional nanosphere lithography (NSL). NSL, which uses self-assembled layers of monodisperse micro/nanospheres as masks, is a low-cost, scalable nanofabrication technique and has been widely employed to fabricate various nanoparticle arrays. Combination with dry etching and/or angled deposition has greatly enriched the family of nanoparticles NSL can yield. In this work, we introduce a variant of this technique, which uses sequential stacking of polystyrene nanosphere monolayers to form a bilayer crystal instead of conventional spontaneous self-assembly. Sequential stacking leads to the formation of moiré patterns other than the usually observed thermodynamically stable configurations. Subsequent O2 plasma etching results in a variety of complex nanostructures. Using the etched moiré patterns as masks, we have fabricated complementary gold nanostructures and studied their optical properties. We believe this facile technique provides a strategy to fabricate complex nanostructures or metasurfaces.

Tunable Nanoantennas for Surface Enhanced Infrared Absorption Spectroscopy by Colloidal Lithography and Post-Fabrication Etching

“…Here we employed various microspheres to tune the corresponding plasmon modes to the spectral region-of-interest for molecular sensing. The monolayers of polystyrene microspheres were fabricated on Si chips using the same method detailed in our previous publication25.…”

“…Therefore, alternative techniques have been proposed such as direct laser writing (DLW)11, nanospherical-lens lithography (NLL)19, and colloidal lithography (CL)20. CL, also known as nanosphere lithography (NSL)2122, is a scalable and cost-effective technique that can generate a variety of metallic nanoparticles2324, even sophisticated metasurfaces when combined with other lithographic techniques such as dry etching2526 or angled-deposition2728. The simplest version of CL uses close-packed colloidal sphere monolayers as deposition masks to create triangular nanoparticle arrays on the substrates underneath.…”

Interfacial Capillary‐Force‐Driven Self‐Assembly of Monolayer Colloidal Crystals for Supersensitive Plasmonic Sensors

“…To achieve high‐performance devices with superior sensitivity and reproducibility, large‐scale and high‐quality PS MCCs are required for the preparation of the patterned functional layers. Till now, various self‐assembly methods, such as spincoating, electrophoretic assembly, vertical deposition, and interface self‐assembly have been proposed to produce hexagonal and quadrangular close packed 2D colloidal arrays. Among them, the Langmuir Blodgett (LB) process based interface self‐assembly method has attracted intensive attention due to its good controllability, high reproducibility, simple configurations, excellent flexibility, and low cost in preparing periodic nanostructure arrays, in which nonpolar solvent (such as hexane, chloroform) is usually employed to trap the hydrophobic colloidal particles at air–water interface.…”

Multiresonant layered plasmonic films

“…Furthermore, this technique allows us to independently design singly resonant films with precisely tailored properties that combine when stacked to form spectrally complex films. In contrast, other techniques to produce single layers of multiresonant plasmonic films require additional fabrication steps such as replica molding to fabricate a patterned surface or sequential deposition of nanospheres, 19,20 adding to the overall cost and time of fabrication. We conclude with the characterization and discussion of multiresonant plasmonic films for applications requiring unique spectral signatures.…”