Bottom-up fabrication approaches to novel plasmonic materials

Abstract

Recent research effort towards developing novel metal nanoparticles (NPs) and their ordered arrays have been motivated by the emergence of plasmonics. In particular, tuning the size, morphology, composition and the separation of metal NPs has allowed us to engineer the collective properties of plasmonic crystals for specific applications. Here we present our recent development of bottom-up growth methods and demonstrate convenience for the preparation of such plasmonic materials. By implementation of physical, chemical, or electrochemical deposition of a metal in combination with micromolding on two-dimensional colloidal crystals, metallic NPs with a variety of morphologies can be created in an ordered lattice. The prepared novel plasmonic crystals could find applications in optics, optoelectronics, materials science, sensing and biophysics. surface plasmons, plasmonic crystal, colloidal crystal, transmission resonance, plasmonic sensor Citation: Chen Z, Zhan P, Dong W, et al. Bottom-up fabrication approaches to novel plasmonic materials. Metal nanoparticles (NPs) have been the subject of many detailed studies because of their distinct optical properties [1-3], which in most cases are associated with localized surface plasmon (SP) resonances [4]. When forming a periodic lattice, plasmon coupling between individual metal NPs may dramatically modify the optical responses [5]. To date, plasmonic materials have been explored for use in a wide range of applications such as waveguides, microscopes, light sources, lithographic tools, solar cells and biosensors [6-9].At present, plasmonic materials targeted for optical applications have mostly been manufactured by electron-beam lithography or focused ion-beam milling. However, these nanofabrication methods suffer the disadvantages of high fabrication cost and relatively long fabrication time, especially for large areas. Sophisticated chemical methods have been developed recently to routinely synthesize individual metallodielectric composite spheres with multi-shell structure [10-13] and metal colloids with controlled morphologies [14][15][16][17]. Nevertheless, it remains challenging to assemble metal NPs into an ordered lattice [8,[18][19][20] because of the difficulty in obtaining uniform NPs. Here, we summarize our recent development of bottom-up growth methods for the fabrication of plasmonic materials and demonstrate how large scale two-dimensional (2D) arrays of metallic NPs with controllable morphologies can be fabricated through colloidal crystal (CC) templating. In addition, our ability to control the shape of local elements allows for tunability of the optical response of the created plasmonic materials over the near-infrared (NIR) and visible spectrum range.

Thermal stability of ultrathin and high dielectric ta‐C films coated with Ag nanostructures for SERS

“…Through the self‐assembled template and filtered cathodic vacuum arc deposition, 1‐nm ta‐C‐coated Ag nanosphere arrays were fabricated well. To observe the structure of Ag/ta‐C hybrids, high‐resolution TEM cross‐sectional analysis was performed, as shown in Figure a.…”

“…Briefly, a large‐area 2D colloidal crystal consisting of hexagonally close‐packed SiO 2 microspheres (Duke Scientific) is first self‐assembled on a quartz chip . Followed by a proper physical deposition, the ordered Ag nanosphere arrays are obtained in which the thickness of Ag layer is finely controlled to 70 nm.…”

“…Briefly, a large-area 2D colloidal crystal consisting of hexagonally close-packed SiO 2 microspheres (Duke Scientific) is first self-assembled on a quartz chip. [24] Followed by a proper physical deposition, the ordered Ag nanosphere arrays are obtained in which the thickness of Ag layer is finely controlled to 70 nm. Note that, because the optical response of such kind of microstructure is determined by the size of SiO 2 microspheres, those with original diameter (D) of 400 nm are selected in the following experiments to ensure that the wavelengths of exciting laser are located within the absorption band of the microstructure.…”

Bowl Shaped Oxide‐Templated Gold Nanostructured Arrays and Structure‐Induced Hydrophilic–Hydrophobic Transition and Molecular Trapping Effect

“…Topdown strategies includes reaction ion etching, [11] electron beam lithography, [12] ion beam lithography, [13] optical lithography, [14] and nanoimprint, [15] etc. [16] while the bottom-up methods involve self-assembly, [17] template-based syntheses, [18] solution growth, [19] physical/chemical deposition, [20] electrophoresis/electro-deposition, [21,22] and so on. [23] Comparatively, the former could offer consistent structures, precise controllability, and reliable repeatability, but come with notable disadvantages, including the requirement for complex equipment, high costs, challenges in scaling up production, and difficulties in fabricating the arrays with intricate designs.…”

Near-Infrared Plasmonic Copper Nanocups Fabricated by Template-Assisted Magnetron Sputtering

“…While the idea of using colloidal templates to assist the fabrication of plasmonic nanostructures has been explored by other researchers before − and summarized by Dorpe et al, the vast majority of those studies focused on noble metals such as gold and silver, and the nanostructures, be them nanocups, nanocaps, or half-shells, were often interconnected with neighboring nanostructures. One exception is the paper by Jian et al, in which the authors experimentally and theoretically studied copper and aluminum nanocups fabricated on sparse colloidal templates.…”