Conversion of Metallic Single-Walled Carbon Nanotube Networks to Semiconducting through Electrochemical Ornamentation

Abstract

Field-effect transistors (FETs) that incorporate single-walled carbon nanotube (SWNT) networks experience decreased on-off current ratios (I(on)/I(off)) due to the presence of metallic nanotubes. Herein, we describe a method to increase I(on)/I(off) without the need for either specialized SWNT growth methods or post growth processing steps to remove metallic nanotubes. SWNTs that were grown using conventional arc discharge methods were deposited from aqueous suspension. Then, the SWNTs in the network were decorated with Cu2O nanoparticles that acted as controllable valves that restricted current flow at positive gate voltages. This resulted in an unprecedented reduction in I(off), as the sub-10 nm sized nanoclusters acted as numerous tunable valves, providing greatly improved network sensitivity to gate voltages in the relatively small range of ±10 V, increasing I(on)/I(off) by up to 205-fold. Larger nanoclusters were found to increase the network conductivity but decrease I(on)/I(off). The ability to convert metallic SWNTs to semiconducting without removing them allows for enhanced I(on) and lower noise while still achieving greatly enhanced magnitudes of I(on)/I(off).

Individual SWCNT Transistor with Photosensitive Planar Junction Induced by Two‐Photon Oxidation

“…[ 20 ] The light‐induced defect generation in carbon lattice by oxygen chemical adsorption either in the form of epoxy or ether groups [ 17,21 ] is a high‐potential method for local tuning of carbon nanomaterials properties. Moreover, several approaches for a nanotube local conversion by oxygen species grafting were suggested based on electrochemical doping [ 22 ] and plasmon‐induced selective oxidation [ 23 ] that poses the local presence of nanoparticles near the nanotube. Recently, the direct laser writing methods of two‐photon oxidation (TPO) of graphene and carbon nanotubes were demonstrated.…”

Selective distributions of functionalized single-walled carbon nanotubes in a polymeric reverse hexagonal phase

“…Many efforts have been made for this purpose using various methods such as solvent evaporation, 10,11 electric field, 12,13 magnetic field, 14,15 and flow field. [16][17][18] However, the SWNT superstructures achieved with these methods have been limited to simple ones such as oriented SWNTs on substrates 19,20 or nematic SWNTs in bulk. 21,22 Recently, amphiphilic molecules such as block copolymers, which exhibit rich phase behavior [23][24][25] and have been extensively used as templates for highly ordered hybrid nanostructured materials selectively incorporating nanoparticles, [26][27][28][29][30] have been proposed as an efficient route for fabricating SWNT superstructures with various architectures.…”

Morphology variation of single walled carbon nanotubes networks by lithography technology for improvement of field effect transistors

“…Current burning of the m-SWNTs in the active channel and post-channel-deposition treatment with chemicals which preferentially destroy m-SWNTs or convert them into s-SWNTs has been studied. [10][11][12] due to the fairly length of ~ 10 μm, the strips of 5 μm are formed to achieve mobility of 80 cm 2 /V-s and on/off ratio of 10 5 . [13] However, for generally shorter solution-processed SWNTs whose length is usually less than 5µm, the width of strips should go down to sub-micron dimension and the resultant short nanotubes may likely result in poor on-current and mobility.…”

“…10 shows the variation with channel length and strip width of the on/off ratio, on-current and mobility using DB71-sorted AP-SWNTs on HfO 2 /Si substrates.It is observed that with HfO 2 /Si wafer and DB71-sorted AP-SWNTs could achieve an on-current of 10.9±1.85×10 -3 μA/μm, and high mobility and on/off ratio of 21.9±8.72 cm 2 /V-s and 8.16x10 4 ±3.04×10 4 respectively. The combination of stripping and s-SWNT enrichment on HfO 2 dielectric substrates results in significantly improved performance over the unsorted and DB71-sorted AP-SWNTs on SiO 2 dielectric devices.…”