Directed nucleation of ordered nanoparticle arrays on amorphous surfaces

Coffee, Shawn S.; Stanley, Scott K.; Ekerdt, John G.

doi:10.1116/1.2221318

Cited by 12 publications

(12 citation statements)

References 37 publications

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“…This bottom-up approach to nanofabrication is extremely versatile; BCP films have been used as sacrificial contact masks for thin-film lithography to produce nanometer-scale periodic patterns in a wide variety of materials, [1][2][3] which have been investigated in the data storage sector for high-density magnetic [4,5] and nano-crystal FLASH memories. [6,7] While the nanoscale domains (spheres, cylinders, etc.) typically organize into grains of micron or smaller size, with no overall orientation, several methods have been developed to direct the domain orientation, or simply increase the grain size, in BCP films.…”

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confidence: 99%

Enhanced Order of Block Copolymer Cylinders in Single‐Layer Films Using a Sweeping Solidification Front

et al. 2007

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The use of block copolymer (BCP) thin films as self-assembled templates has become increasingly popular as an economical nanofabrication technique, with new applications and techniques constantly being developed. This bottom-up approach to nanofabrication is extremely versatile; BCP films have been used as sacrificial contact masks for thin-film lithography to produce nanometer-scale periodic patterns in a wide variety of materials, [1][2][3] which have been investigated in the data storage sector for high-density magnetic [4,5] and nano-crystal FLASH memories. [6,7] While the nanoscale domains (spheres, cylinders, etc.) typically organize into grains of micron or smaller size, with no overall orientation, several methods have been developed to direct the domain orientation, or simply increase the grain size, in BCP films. In the first category, epitaxy [8,9] can direct the alignment over large areas, but requires substrates pre-patterned at the nanometer scale; graphoepitaxy [10][11][12] creates needle-like grains very long in one dimension, but at most a few microns wide; electric fields [13] generate alignment parallel to the field direction over squaremicron areas; polarized light can create arbitrary orientation patterns in liquid-crystalline block copolymers with photoalignable side groups; [14,15] and shear can align BCP cylinders [16] and spheres [17,18] over square-centimeter areas, with an orientation specified by the shear direction. In the second category, uniform solvent annealing [19] can increase BCP grain size to a few microns without imposing a preferential direction to the pattern; by creating a moving gradient in solvent concentration, "zone-casting" from solution can produce macroscopically-aligned specimens. [20] Similarly, uniform thermal annealing [21,22] increases the grain size without imposing a preferential direction, but the grain size grows only as the 1 ⁄4 power of annealing time; the effect of a moving temperature gradient on a block copolymer thin film has not been reported previously.Hashimoto et al. [23] showed that sweeping a strong temperature gradient through a bulk specimen of a lamellar BCP, such that the material is heated above its order-disorder transition temperature, can produce strong alignment; as the material cools in the gradient, ordered lamellae grow from the disordered phase, with the lamellar planes aligned normal to the direction of the moving gradient. Though directional solidification has not been reported for neat BCP thin films, directional crystallization of a small-molecule solvent from a BCP solution has been reported by Thomas and co-workers; [24,25] crystallization of the solvent concentrates the BCP and drives it to order, similar to what zone-casting [20] achieves through solvent evaporation. When the solvent is directionally crystallized on a cold substrate, an aligned BCP film is left on the surface of the frozen solvent, but with a defect density higher than obtained with the methods discussed in the preceding paragraph. Our present study demonstr...

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confidence: 99%

Enhanced Order of Block Copolymer Cylinders in Single‐Layer Films Using a Sweeping Solidification Front

et al. 2007

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“…Selective growth of Si on arrays of Si 3 N 4 surfaces defined through a sacrificial SiO 2 hard mask is qualitatively similar to the selective growth of Ge on HfO 2 defined through a sacrificial SiO 2 mask [7]. In both cases the inability of Si or Ge to accumulate on SiO 2 , yet accumulate on the growth surface, enables selective deposition at the bottom of the features defined through the SiO 2 mask.…”

Section: Discussionmentioning

confidence: 95%

“…(d) The negative image of Part c with circles around the 16 black spots that correspond to particles greater than 5 nm in diameter. nanoparticles to better control the process [7] and it permits a wide range of radical fluxes to be explored to optimize the process [23].…”

Section: Discussionmentioning

confidence: 99%

“…We have previously shown with Ge [7] that selective nanoparticle placement is possible during hot wire chemical vapor deposition (HWCVD) by employing a thin (12 nm) SiO 2 mask through which $22 nm vias are etched to expose HfO 2 . The more facile etching by adsorbed Ge of SiO 2 versus HfO 2 [8] affords a kinetic window between 700 and 800 K in which the Ge adatoms can accumulate on HfO 2 and not on SiO 2 , and eventually nucleate and grow into nanoparticles selectively on the HfO 2 regions.…”

Section: Introductionmentioning

confidence: 99%

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Selective silicon nanoparticle growth on high-density arrays of silicon nitride

Coffee¹,

Shahrjerdi²,

Banerjee³

et al. 2007

Journal of Crystal Growth

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“…Surface chemistry governs the formation of nanocrystals. Directed nucleation and growth of nanocrystals is examined within macroscopic (~100 μιη) to nanoscopic (~20 nm) range [56][57]. Below a critical size, nanocrystal formation is sharply affected.…”

Section: The Classical Crystal Growth Kineticsmentioning

confidence: 99%

Mode of Growth Mechanism of Nanocrystal Using Biomolecules

Sanjay

Singh

Tiwari

et al. 2012

Intelligent Nanomaterials

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A structure decides its functional mode. For a chemist, a physicist, a biologist, or an engineer, the credibility of their work only depends on how efficiently they can translate the structural aspect of a nanocrystal to its functional aspect in any biological system. The macromolecules are known to control their local chemical environment, allowing access to seemingly unfavorable reaction pathways. Surface chemistry governs the nucleation, growth and self-assembly of nanostructures on surfaces. Below a critical size, the formation of nanocrystals is sharply affected and its properties are impacted as a result. So it is very important to achieve the desired results through the judicious choice of reaction conditions. Biomolecules, such as proteins, peptides, nucleic acids, fatty acids, or any of the phosphates, all have their characteristic functional groups, whether it is amide, sulphide, carbonyl, or carboxyl group. The main advantage of utilizing these biomolecules as precursors for the synthesis of nanocrystals is that they have a huge molecular library, enabling a combinatorial approach to achieve nanocrystals of a desired shape and size.When a nanocrystal grows, due to confinement in size, the surface molecules/atoms remain unsatisfied giving rise to dangling bonds. The interaction of these bonds with biomolecules results in very interesting morphologies. The growth mechanism of nanocrystals with biomolecules may proceed through hydrophobic, hydrophilic, ionic, nonionic or hydrogen bond interactions. The pathway depends on the mode of synthesis, nature of the functional group, and concentration of biomolecules.

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Directed nucleation of ordered nanoparticle arrays on amorphous surfaces

Cited by 12 publications

References 37 publications

Enhanced Order of Block Copolymer Cylinders in Single‐Layer Films Using a Sweeping Solidification Front

Enhanced Order of Block Copolymer Cylinders in Single‐Layer Films Using a Sweeping Solidification Front

Selective silicon nanoparticle growth on high-density arrays of silicon nitride

Mode of Growth Mechanism of Nanocrystal Using Biomolecules

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