Template-Induced Structure Transition in Sub-10 nm Self-Assembling Nanoparticles

Abstract

We report on the directed self-assembly of sub-10 nm gold nanoparticles confined within a template comprising channels of gradually varying widths. When the colloidal lattice parameter is mismatched with the channel width, the nanoparticles rearrange and break their natural close-packed ordering, transiting through a range of structural configurations according to the constraints imposed by the channel. While much work has been done in assembling ordered configurations, studies of the transition regime between ordered states have been limited to microparticles under applied compression. Here, with coordinated experiments and Monte Carlo simulations we show that particles transit through a more diverse set of self-assembled configurations than observed for compressed systems. The new insight from this work could lead to the control and design of complex self-assembled patterns other than periodic arrays of ordered particles.

Directed Self-Assembly of sub-10 nm Particles: Role of Driving Forces and Template Geometry in Packing and Ordering

“…Our recent experimental observations 16 also suggests another possible mechanism of DSA-n in which the repulsive part of particles pair potential as well as attractive capillary forces are playing the major role. In our proposed mechanism, an attractive capillary force is applied by the meniscus onto the first layer of particles at the free surface of the contact line where the particles concentration is normally high.…”

Second-Harmonic Generation from Sub-5 nm Gaps by Directed Self-Assembly of Nanoparticles onto Template-Stripped Gold Substrates

“…11,12 Selfassembly is a promising approach to achieve sub-5-nm gaps between close-packed particles, in which molecular ligands coating the particles act as precise dielectric spacers. [13][14][15][16] Similarly, gaps can be defined with particles deposited onto a metal film, [17][18][19] and with edge lithography using atomic-layer deposition. 20 In comparison, top-down lithography defines gaps directly and deterministically, but resolution limits and surface roughness precludes patterning at sub-5-nm dimensions in a scalable manner.…”

“…1(e) with trenches that were ~11 nm wide. Using a recently-developed directed self-assembly approach of sub-10 nm nanoparticles (DSA-n), 16,42 oleylamine-coated gold nanoparticles of ~8 nm core diameter were selectively deposited into the trenches to form sub-5-nm gaps on either side of the particle as shown in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 9 fracturing the silicon fins despite their high aspect-ratio of ~5. This high aspect-ratio is important to achieve the localized gap plasmon resonances as shown in the finite-difference time-domain (FDTD) simulations in Fig.…”

Survey of plasmonic gaps tuned at sub-nanometer scale in self-assembled arrays

“…Besides self-assembly within a confined volume, assembly of the colloidal NPs may be directed by templates with comparable feature sizes [52,53]. Slightly tapered nanopillar arrays have been employed as the templates, since colloidal nanospheres can be deposited in the vacancies between adjacent nanopillars [54,55].…”

“…Whether and where the NP strips are created within a confined space on the micron scale depends on the magnitude of the contact angle, which can be quantitatively characterized by light interference (See Fig. 3) [50,51].Besides self-assembly within a confined volume, assembly of the colloidal NPs may be directed by templates with comparable feature sizes [52,53]. Slightly tapered nanopillar arrays have been employed as the templates, since colloidal nanospheres can be deposited in the vacancies between adjacent nanopillars [54,55].…”