Topological Transitions in Carbon Nanotube Networks via Nanoscale Confinement

Abstract

Efforts aimed at large-scale integration of nanoelectronic devices that exploit the superior electronic and mechanical properties of single-walled carbon nanotubes (SWCNTs) remain limited by the difficulties associated with manipulation and packaging of individual SWNTs. Alternative approaches based on ultrathin carbon nanotube networks (CNNs) have enjoyed success of late with the realization of several scalable device applications. However, precise control over the network electronic transport is challenging due to (i) an often uncontrollable interplay between network coverage and its detailed topology and (ii) the inherent electrical heterogeneity of the constituent SWNTs. In this article, we use template-assisted fluidic assembly of SWCNT networks to explore the effect of geometric confinement on the network topology. Heterogeneous SWCNT networks dip-coated onto submicrometer wide ultrathin polymer channels become increasingly aligned with decreasing channel width and thickness. Experimental-scale coarse-grained computations of interacting SWCNTs show that the effect is a reflection of a topology that is no longer dependent on the network density, which in turn emerges as a robust knob that can induce semiconductor-to-metallic transitions in the network response. Our study demonstrates the effectiveness of directed assembly on channels with varying degrees of confinement as a simple tool to tailor the conductance of the otherwise heterogeneous network, opening up the possibility of robust large-scale CNN-based devices.

Sculpting carbon bonds for allotropic transformation through solid-state re-engineering of –sp2 carbon

“…As shown in the Fig. 4a, nanotubes in both edges are more highly aligned because of the capillary force-induced assembly of SWCNTs 30,32 . Highly excited electrons for V a ¼ 0.8V b constantly transfer their energy to the nanotube lattice.…”

“…The basic steps for building organized SWCNT lateral architectures fabricated using the template-guided fluidic assembly process [30][31][32] , are as follows. First, a 300-nm-thick polymethyl methacrylate photoresist is deposited on a substrate and baked at 160°C for 90 s. Second, polymethyl methacrylate patterns are constructed on the substrate using electronbeam lithography to build nanoscale channels, which form templates for building the test architectures and these templates are then developed in the solution (methyl isobutyl ketone/isopropyl alcohol ¼ 1:3) for 100 s followed by a 30-s rinse in isopropyl alcohol solution.…”

“…Highly organized SWCNT micronetworks containing about (2 ± 0.5) Â 10 4 CNTs per mm 2 were assembled by using a template-guided fluidic assembly process [30][31][32] and attached with electrodes for electrical treatment. Particularly for TEM observation, welldefined SWCNT microlines (see Method section) were directly assembled on specially designed TEM grids where microwindows were located between built-in micro-heaters for external heating.…”

High‐Rate Nanoscale Offset Printing Process Using Directed Assembly and Transfer of Nanomaterials

“…Furthermore, using self-assembly and fl uidic assembly, researchers have reported that the alignment of SWNTs strongly depends on the relation between the length of SWNTs and the width of the pattern (trench). [ 47,48 ] Park et al assembled SWNTs on the desired position by an ion-exchange process. Taking advantage of the fl uidic interface and electrode/ nanotube geometry, we have been able to assemble aligned SWNTs onto features from the suspension.…”

Interfacial shear stress between a single-walled carbon nanotube and a gold surface after different physical treatments

“…With the adhesion or friction between tubes and substrates affecting the fabrication and the performance of SWNT-based nanodevices [6][7][8][9][10][11][12], it is also very important to develop an understanding of how these processes affect the mechanical shear stress between CNTs and gold surfaces.…”