skip to main content


Title: Precise pitch-scaling of carbon nanotube arrays within three-dimensional DNA nanotrenches

Precise fabrication of semiconducting carbon nanotubes (CNTs) into densely aligned evenly spaced arrays is required for ultrascaled technology nodes. We report the precise scaling of inter-CNT pitch using a supramolecular assembly method called spatially hindered integration of nanotube electronics. Specifically, by using DNA brick crystal-based nanotrenches to align DNA-wrapped CNTs through DNA hybridization, we constructed parallel CNT arrays with a uniform pitch as small as 10.4 nanometers, at an angular deviation <2° and an assembly yield >95%.

 
more » « less
Award ID(s):
1729397
PAR ID:
10155552
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
American Association for the Advancement of Science (AAAS)
Date Published:
Journal Name:
Science
Volume:
368
Issue:
6493
ISSN:
0036-8075
Page Range / eLocation ID:
p. 874-877
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. Organization of carbon nanotubes (CNTs) within epoxy matrices can be effectively achieved using magnetic field application. In our previous experimental work, multi-walled CNTs were magnetized, diazotized, and magnetically aligned to form aligned CNT-epoxy composites. While effective toughness improvement was experimentally observed with small CNT addition, more understanding about magnetic assembly of CNTs is desired, to effectively complete CNT assembly before the epoxy cures and also to avoid re-agglomeration of CNTs. In this work, assembly behaviors of ellipsoid particles, that simulate CNT bundles, in a fluid domain, that simulates the epoxy matrix, under the static magnetic field are being studied. Higher ellipsoid aspect ratio was observed to be effective to decrease the magnetic assembly time, while some ellipsoid lower aspect ratio and larger original ellipsoid separate distance combination prevented their magnetic assembly. When assembly is achieved, the assembly time was observed to be much smaller (<0.1 second) than the currently dedicated assembly time in our experiments (~10s of minutes). Further studies with more ellipsoids, varying ellipsoid positions, and increasing magnetic field strength are planned in future. 
    more » « less
  2. null (Ed.)
    Selective deposition of semiconducting carbon nanotubes (s-CNTs) into densely packed, aligned arrays of individualized s-CNTs is necessary to realize their potential in semiconductor electronics. We report the combination of chemical contrast patterns, topography, and pre-alignment of s-CNTs via shear to achieve selective-area deposition of aligned arrays of s-CNTs. Alternate stripes of surfaces favorable and unfavorable to s-CNT adsorption were patterned with widths varying from 2000 nm down to 100 nm. Addition of topography to the chemical contrast patterns combined with shear enabled the selective-area deposition of arrays of quasi-aligned s-CNTs (∼14°) even in patterns that are wider than the length of individual nanotubes (>500 nm). When the width of the chemical and topographical contrast patterns is less than the length of individual nanotubes (<500 nm), confinement effects become dominant enabling the selective-area deposition of much more tightly aligned s-CNTs (∼7°). At a trench width of 100 nm, we demonstrate the lowest standard deviation in alignment degree of 7.6 ± 0.3° at a deposition shear rate of 4600 s −1 , while maintaining an individualized s-CNT density greater than 30 CNTs μm −1 . Chemical contrast alone enables selective-area deposition, but chemical contrast in addition to topography enables more effective selective-area deposition and stronger confinement effects, with the advantage of removal of nanotubes deposited in spurious areas via selective lift-off of the topographical features. These findings provide a methodology that is inherently scalable, and a means to deposit spatially selective, aligned s-CNT arrays for next-generation semiconducting devices. 
    more » « less
  3. All prior work on modeling the full-wave electromagnetic response of carbon nanotubes (CNTs) have focused on CNTs in free-space, whereas in most practical applications, CNTs are embedded in a dielectric substrate. In this work, we use full-wave simulations to study the plasmonic resonances of CNT dimers embedded in a lossy dielectric slab with a finite thickness. The numerical results show that the finite thickness dielectric slab leads to the emergence of new CNT resonance behavior that is not present in a homogeneous environment. As a single CNT approaches the dielectric slab interfaces, the resonance frequency of the CNT increases due to reduced dielectric loading. The resonance behavior changes completely when two CNTs in proximity form a dimer near the slab interface. The bonding and antibonding resonances of CNT dimers and the absorbed power vary significantly with the distance between the slab interface and the CNT dimer. Using this phenomenon, we show that symmetric CNT dimers can behave like asymmetric CNT dimers. Also, the antibonding resonance of an asymmetric CNT dimer can be suppressed by adjusting the length and depth of the CNT dimer inside the slab. This work can guide future sensing modalities based on CNT dimer as well as can provide an accurate assessment of the proximity of a CNT network to the interface of the embedding substrate.

     
    more » « less
  4. Carbon nanotubes (CNTs) offer unique properties that have the potential to address multiple issues in industry and material sciences. Although many synthesis methods have been developed, it remains difficult to control CNT characteristics. Here, with the goal of achieving such control, we report a bottom-up process for CNT synthesis in which monolayers of premade aluminum oxide (Al2O3) and iron oxide (Fe3O4) nanoparticles were anchored on a flat silicon oxide (SiO2) substrate. The nanoparticle dispersion and monolayer assembly of the oleic-acid-stabilized Al2O3 nanoparticles were achieved using 11-phosphonoundecanoic acid as a bifunctional linker, with the phosphonate group binding to the SiO2 substrate and the terminal carboxylate group binding to the nanoparticles. Subsequently, an Fe3O4 monolayer was formed over the Al2O3 layer using the same approach. The assembled Al2O3 and Fe3O4 nanoparticle monolayers acted as a catalyst support and catalyst, respectively, for the growth of vertically aligned CNTs. The CNTs were successfully synthesized using a conventional atmospheric pressure-chemical vapor deposition method with acetylene as the carbon precursor. Thus, these nanoparticle films provide a facile and inexpensive approach for producing homogenous CNTs. 
    more » « less
  5. Abstract

    Carbon nanotube (CNT)‐reinforced polymer fibers have broad applications in electrical, thermal, optical, and smart applications. The key for mechanically robust fibers is the precise microstructural control of these CNTs, including their location, dispersion, and orientation. A new methodology is presented here that combines dry‐jet‐wet spinning and forced assembly for scalable fabrication of fiber composites, consisting of alternating layers of polyacrylonitrile (PAN) and CNT/PAN. The thickness of each layer is controlled during the multiplication process, with resolutions down to the nanometer scale. The introduction of alternating layers facilitates the quality of CNT dispersion due to nanoscale confinement, and at the same time, enhances their orientation due to shear stress generated at each layer interface. In a demonstration example, with 0.5 wt% CNTs loading and the inclusion of 170 nm thick layers, a composite fiber shows a significant mechanical enhancement, namely, a 46.4% increase in modulus and a 39.5% increase in strength compared to a pure PAN fiber. Beyond mechanical reinforcement, the presented fabrication method is expected to have enormous potential for scalable fabrication of polymer nanocomposites with complex structural features for versatile applications.

     
    more » « less