Development of a polystyrene colloidal monolayer processin the technology of microsphere lithography

The study introduces an operation of deposition of a polystyrene microspheres monolayer from a colloidal suspension, based on the Langmuir ― Blodgett method. The operation plays a key role in the technology of microsphere lithography. The paper describes the laboratory equipment developed to produce ordered colloidal films and monolayers, shows the main modes of the process, and presents the results of studying the surfaces of samples using an atomic force microscope. Findings of research show that the films obtained are close-packed monolayers of microspheres in accordance with the hexagonal symmetry, which are suitable to be used as templates. By means of them and by the method of microsphere lithography, it is possible to obtain regular arrays of nanoparticles of a given size for products of photonics, sensorics, and nanoelectronics.

Plasma Fabrication and SERS Functionality of Gold Crowned Silicon Submicrometer Pillars

Sequential plasma processes combined with specific lithographic methods allow for the fabrication of advanced material structures. In the present work, we used self-assembled colloidal monolayers as lithographic structures for the conformation of ordered Si submicrometer pillars by reactive ion etching. We explored different discharge conditions to optimize the Si pillar geometry. Selected structures were further decorated with gold by conventional sputtering, prior to colloidal monolayer lift-off. The resulting structures consist of a gold crown, that is, a cylindrical coating on the edge of the Si pillar and a cavity on top. We analysed the Au structures in terms of electronic properties by using X-ray absorption spectroscopy (XAS) prior to and after post-processing with thermal annealing at 300 °C and/or interaction with a gold etchant solution (KI). The angular dependent analysis of the plasmonic properties was studied with Fourier transformed UV-vis measurements. Certain conditions were selected to perform a surface enhanced Raman spectroscopy (SERS) evaluation of these platforms with two model dyes, prior to confirming the potential interest for a well-resolved analysis of filtered blood plasma.

Charging-driven coarsening and melting of a colloidal nanoparticle monolayer at an ionic liquid–vacuum interface

We induce and investigate the coarsening and melting dynamics of an initially static nanoparticle colloidal monolayer at an ionic liquid–vacuum interface, driven by a focused, scanning electron beam.

High-transmittance and focal controllable plano-convex lenses with embedded nanolens bottoms formed by electrowetting on a colloidal monolayer

UV-curable polymer lenses with a nanolens array decorated on the bottom surface via irreversible electrowetting on a hydrophobic colloidal monolayer.

Glancing angle deposition meets colloidal lithography: a new evolution in the design of nanostructures

The combination of colloidal lithography and glancing angle deposition facilitates a new powerful fabrication technique – shadow sphere lithography (SSL), which can greatly expand the variety and complexity of nanostructures fabricated using simple evaporation and colloidal monolayer templates. Their applications have been widely investigated in plasmonics and associated fields. Here, we present an overview of the principle of SSL, followed by different strategies of utilizing SSL to design various nanostructures by changing the nanosphere monolayer masks, deposition configurations, different ways to combine deposition and etching, etc. Typical nanostructures fabricated by SSL, including nanorods on nanospheres, patchy nanospheres, nanotriangles, nanoring, nanocrescents, etc., are introduced. Recent optical applications of these plasmonic nanostructures are also summarized. It is expected that this review will inspire more ingenious designs of plasmonic nanostructures by SSL for advanced and smart applications.