Enhanced Tunability of Gold Nanoparticle Size, Spacing, and Shape for Large-Scale Plasmonic Arrays

Abstract

Gold nanoparticles are important constituents in plasmonic arrays, lending themselves to electronic, optical, biomedical, sensing, and catalytic applications, among numerous others. Process variables that must be controlled when engineering plasmonic nanoparticle ensembles include nanoparticle size, shape, and spatial distribution on surfaces. The challenge in generating arrays of nanoparticles with control over these three parameters increases dramatically as spatial requirements for uniformity extend to larger processing areas. We present a procedure that exploits thermally driven solid-state diffusional dewetting to yield considerable flexibility in generating ensembles of gold nanoparticles. Such submelting dewetting introduces fine control over particle spatial features that are currently difficult to achieve through conventional methods of generating nanoparticle arrays. Because of the simplicity of the process and its areascalability, solid-state diffusional dewetting is shown here to be a method that could be easily scaled up to apply to large-area plasmonic fabrication processes.

Designer Metasurfaces for Antireflective Applications Enabled by Advanced Nanoparticle Technology

“…That initial film is dewetted through solid‐state dewetting, which is also known to provide additional tunability to the resultant nanoparticle size and spacing through processing temperature selection. [ 17 ] Following this first deposition/dewetting process, gold films of identical thickness can be deposited and subsequently dewet, resulting in nanoparticle lateral growth and height increase, while the period experiences minimal increase. This iterative process is repeated until the desired gold nanoparticle spatial parameters are obtained; when utilized for AR MS masks, this approach opens a completely new parameter space in which it is possible to increase particle height without sacrificing a substantial increase in particle spacing.…”

“…Additional considerations that may guide MS feature geometry selection include physical properties of the fabricated structures (i.e., mechanical robustness of pillars versus pyramids, water affinity, etc.) and the ability to spatially vary the index of refraction through FF control to generate optical functionality, [16][17][18][19] which cannot be done utilizing 100% sidewall sloping.…”

“…These trends in solid-state dewetting have been detailed elsewhere. [17] Figure 1. Reflectance contours a-c) as functions of feature height and fill factor for different sidewall sloping and d-f) as functions of incident wavelength and feature height for a prescribed fill factor of 60%.…”

“…For processes using etching masks fabricated by self-assembly of nanoparticles, as reported recently, the mask particle size and resultant inter-feature spacing can be tuned to length scales suitable for wavelengths spanning from the UV to the NIR. [17,18] However, the challenge has been to control the feature-feature length scales for the MS to operate at these wavelengths while simultaneously enabling the MS to perform well as an AR (which will depend on the MS feature height, geometry, and wavelength). For this reason, substrate-engraved MS fabricated via etching masks is the focus of this paper.…”

Chemosensing on Miniaturized Plasmonic Substrates

“…Thus, indium tin oxide (ITO) was used for its conductivity and high optical transmittance, and due to their excellent conductive properties [ 21 , 22 , 23 ], an array of gold nanoparticles on ITO was used for SERS measurements [ 24 ]. Moreover, the plasmonic performance of metallic NPs depends on the chemical compositions and physical dimensions of the metallic nanoparticles [ 25 , 26 ].…”