title: Effect of Polymer Gate Dielectrics on Charge Transport in Carbon Nanotube Network Transistors: Low-k Insulator for Favorable Active Interface.
abstract: Charge transport in carbon nanotube network transistors strongly depends on the properties of the gate dielectric that is in direct contact with the semiconducting carbon nanotubes. In this work, we investigate the dielectric effects on charge transport in polymer-sorted semiconducting single-walled carbon nanotube field-effect transistors (s-SWNT-FETs) by using three different polymer insulators: A low-permittivity (εr) fluoropolymer (CYTOP, εr= 1.8), poly(methyl methacrylate) (PMMA, εr= 3.3), and a high-εrferroelectric relaxor [P(VDF-TrFE-CTFE), εr= 14.2]. The s-SWNT-FETs with polymer dielectrics show typical ambipolar charge transport with high ON/OFF ratios (up to ∼105) and mobilities (hole mobility up to 6.77 cm2V-1s-1for CYTOP). The s-SWNT-FET with the lowest-k dielectric, CYTOP, exhibits the highest mobility owing to formation of a favorable interface for charge transport, which is confirmed by the lowest activation energies, evaluated by the fluctuation-induced tunneling model (FIT) and the traditional Arrhenius model (EaFIT= 60.2 meV and EaArr= 10 meV). The operational stability of the devices showed a good agreement with the activation energies trend (drain current decay ∼14%, threshold voltage shift ∼0.26 V in p-type regime of CYTOP devices). The poor performance in high-εrdevices is accounted for by a large energetic disorder caused by the randomly oriented dipoles in high-k dielectrics. In conclusion, the low-k dielectric forms a favorable interface with s-SWNTs for efficient charge transport in s-SWNT-FETs.
authors.affiliation: Department of Nanobio Materials and Electronics, School of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology (GIST) , 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, Republic of Korea.|Department of Energy and Materials Engineering, Dongguk University , 26 Pil-dong, 3-ga, Jung-gu, Seoul 100-715, Republic of Korea.
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: Lee
authors.affiliation: Department of Energy and Materials Engineering, Dongguk University , 26 Pil-dong, 3-ga, Jung-gu, Seoul 100-715, Republic of Korea.
authors.forename: Yong
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Physics and Centre for Plastic Electronics, Blackett Laboratory, Imperial College London , London SW7 2AZ, U.K.
authors.forename: Dongyoon
authors.initials: D
authors.lastname: Khim
authors.affiliation: Department of Energy and Materials Engineering, Dongguk University , 26 Pil-dong, 3-ga, Jung-gu, Seoul 100-715, Republic of Korea.
authors.forename: Won-Tae
authors.initials: WT
authors.lastname: Park
authors.affiliation: Department of Nanobio Materials and Electronics, School of Materials Science and Engineering, Heeger Center for Advanced Materials, Gwangju Institute of Science and Technology (GIST) , 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, Republic of Korea.
authors.forename: Dong-Yu
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Department of Energy and Materials Engineering, Dongguk University , 26 Pil-dong, 3-ga, Jung-gu, Seoul 100-715, Republic of Korea.
authors.forename: Yong-Young
authors.initials: YY
authors.lastname: Noh
keywords: carbon nanotube field-effect transistors; charge transport; conjugated polymer wrapped single wall carbon nanotube; gate dielectrics; polymer dielectrics