Thin Film Nanotube Transistors Based on Self-Assembled, Aligned, Semiconducting Carbon Nanotube Arrays

Abstract

Thin film transistors (TFTs) are now poised to revolutionize the display, sensor, and flexible electronics markets. However, there is a limited choice of channel materials compatible with low-temperature processing. This has inhibited the fabrication of high electrical performance TFTs. Single-walled carbon nanotubes (CNTs) have very high mobilities and can be solution-processed, making thin film CNT-based TFTs a natural direction for exploration. The two main challenges facing CNT-TFTs are the difficulty of placing and aligning CNTs over large areas and low on/off current ratios due to admixture of metallic nanotubes. Here, we report the self-assembly and self-alignment of CNTs from solution into micron-wide strips that form regular arrays of dense and highly aligned CNT films covering the entire chip, which is ideally suitable for device fabrication. The films are formed from pre-separated, 99% purely semiconducting CNTs and, as a result, the CNT-TFTs exhibit simultaneously high drive currents and large on/off current ratios. Moreover, they deliver strong photocurrents and are also both photo- and electroluminescent.

Fundamental Performance Limits of Carbon Nanotube Thin-Film Transistors Achieved Using Hybrid Molecular Dielectrics

“…20 P-type CNT TFTs show higher on/off ratios than ambipolar devices where both minority electrons and holes are present in the channel in the off-state, resulting in larger off-currents. 40 The present devices also exhibit significantly higher transconductance at an on/off ratio ~10 5 due to the combined high conductance and low voltage operation (Fig.…”

Chirality-controlled synthesis of single-wall carbon nanotubes using vapour-phase epitaxy

“…Selective synthesis of semiconducting or metallic predominated SWCNTs has already been achieved through controlled chemical vapour deposition (CVD) growth [16][17][18] , enabling the fabrication of nanotube field-effect transistors using predominantly semiconducting SWCNTs 19,20 . As a next step, synthesis of SWCNTs with predefined chirality is highly desired.…”

Capacitance-Voltage Characteristics of Thin-film Transistors Fabricated with Solution-Processed Semiconducting Carbon Nanotube Networks

“…On the other hand, using random networks of carbon nanotubes for applications in thin-film transistors (TFTs) has recently shown great promise. Such devices offer mechanical flexibility and optical transparency and can be easily fabricated in a scalable fashion with far superior device performance and long-term air-stability compared with amorphous silicon or organic semiconductors [5][6][7][8][9][10][11]. Among various approaches used for assembling random carbon nanotube networks, solution-processed semiconductor-enriched carbon nanotubes possess additional advantages of low-cost and room temperature processes [6,[8][9][10]12].…”

“…Such devices offer mechanical flexibility and optical transparency and can be easily fabricated in a scalable fashion with far superior device performance and long-term air-stability compared with amorphous silicon or organic semiconductors [5][6][7][8][9][10][11]. Among various approaches used for assembling random carbon nanotube networks, solution-processed semiconductor-enriched carbon nanotubes possess additional advantages of low-cost and room temperature processes [6,[8][9][10]12]. With the ongoing pavement towards reliable dispersion of longer nanotubes with higher purity separation process [13], largescale, high-performance, flexible carbon nanotube TFTs have already found wide applications in compliant integrated circuits, organic light-emitting displays, and electronic skins [5,9,11,14].…”