Self-ordering of small-diameter metal nanoparticles by dewetting on hexagonal mesh templates

Abstract

Arrays of small-diameter nanoparticles with high spatial order are useful for chemical and biological sensors, data storage, synthesis of nanowires and nanotubes, and many other applications. We show that self-ordered metal nanoparticle arrays can be formed by dewetting of thin films on hexagonal mesh substrates made of anodic aluminum oxide (AAO). Upon heating, the metal (Fe) film dewets onto the interstitial sites (i.e., the node points) between pores on the top surface of the AAO. We investigated the particle morphology and dynamics of dewetting using a combination of atomic force microscopy (AFM), grazing-incidence small-angle X-ray scattering (GISAXS), and numerical simulations. Templated metal particles are more monodisperse and have higher local order than those formed by the same dewetting process on flat, nonporous alumina. The degree of order depends on the initial film thickness, and for the optimal thickness tested (nominally 2 nm), we achieved uniform coverage and high order of the particles, comparable to that of the AAO template itself. Computational modeling of dewetting on templates with various pore order and size shows that the order of AAO pores is primarily influential in determining particle position and spacing, while the variance in pore size is less impactful. Potential uses of these ordered nanoparticle arrays on porous materials include plasmonic sensors and spatially controlled catalysts.

Plasmonic Nanocrystal Arrays on Photonic Crystals with Tailored Optical Resonances

“…The formation of AuNCs is attributed to the dewetting of the Au film deposited onto the surface of SiO 2 NP arrangements. 32 Both the AuNC diameter ( d Au ) and their edge-to-edge distance ( p Au ) increase with increasing d SiO2 ( Figure S1 ) where PPMs feature one large AuNC on top and multiple small AuNCs along the rim of each SiO 2 NP. Subsequent deposition of a second continuous Au film on these as-prepared PPMs leads to a narrowing of the p Au ( Figure 1 e).…”

Adjustable metal particle grid formed through upward directed solid-state dewetting using silicon nanowires

“…[8][9][10][11] For the purpose of controlling metal particles on a substrate surface, there has been a swell of interest in metal thin lm dewetting and particle migration behavior. [12][13][14][15] It is known that solid-state dewetting of metal thin lms occurs at temperatures much lower than the metal's bulk melting temperature, which depends greatly on the metal thin lm thickness. 16 At high temperature, metal thin lms will quickly dewet from passive surfaces and contract in order to reduce the lm's surface energy, exposing the underlying surface.…”

Medium energy, heavy and inert ion irradiation of metallic thin films: studies of surface nano‐structuring and metal burrowing

“…For instance, the thermal annealing of thin metallic film (~a few nm in thickness) deposited on a solid surface results in the formation of surface/partially buried metal nano-structures. [7,8] Because of certain advantages such as excellent control on the growth and size distribution, the ion beam synthesis of surface and buried metallic nano-structures received considerable attention in recent years. [9][10][11] The ion beam of any metal can be implanted in any substrate/matrix at desired depth by selecting appropriate energy.…”

“…The varieties of chemical as well as physical methods are being used for the fabrication of metal nano‐structures of different size and shape distributions. For instance, the thermal annealing of thin metallic film (~ a few nm in thickness) deposited on a solid surface results in the formation of surface/partially buried metal nano‐structures . Because of certain advantages such as excellent control on the growth and size distribution, the ion beam synthesis of surface and buried metallic nano‐structures received considerable attention in recent years .…”