Simultaneously grown single wall carbon nanotube channel and electrodes in a thin film transistor
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Simultaneously grown single wall carbon nanotube channel and electrodes in a thin film transistor Jinsup Lee and Bo-Hyun Kim, Department of Material Science and Engineering, NanoCentury KI, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea Seong Jun Kang, Department of Advanced Materials Engineering for Information and Electronics, Kyung Hee University, Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701, Republic of Korea Kar Tham Hyun, Department of Material Science and Engineering, NanoCentury KI, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea Seok-Hee Lee, Department of Electrical Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea Seokwoo Jeon, Department of Material Science and Engineering, NanoCentury KI, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea Address all correspondence to Seokwoo Jeon at [email protected] (Received 17 April 2012; accepted 11 June 2012)
Abstract By chemical vapor deposition, aligned single wall carbon nanotubes (SWNTs) and a network of SWNTs are simultaneously grown as the channel and the source–drain electrodes of thin film transistors (TFTs). The increase of aligned SWNTs increases the channel conductance without changing the contact resistance. However, the increase of network-type SWNTs from 19 to 32.5 (SWNTs/μm) decreases the contact resistance fivefold. The contact resistance of all-SWNT TFT is three times lower compared with that of an SWNT TFT using metal electrodes. The allSWNT TFTs transferred on polyethylene terephthalate (PET) show a transparency of >80% in the visible range of wavelengths.
Introduction Owing to their outstanding electrical properties,[1,2] single wall carbon nanotubes (SWNTs) have shown great potential in various electrical devices such as thin film transistors (TFTs), logic circuits (semiconducting), electrical interconnects, and transparent electrodes (metallic).[3–6] TFTs made of SWNTs look especially promising. The non-uniform chirality of individual SWNTs, however, is an obstacle for uniform electrical properties along with short junctions and high contact resistance.[7] In recent years, two distinctive surface-assisted growth modes, serpentine[8] and parallel growth,[9,10] have been developed for SWNT alignment to prevent cross contacting between nanotubes. These two growth modes, depending on the flow direction of the carbon feed gas relative to the orientation of the atomic step edge of substrates, enable the fabrication of homogeneous SWNTs of the same type between two electrodes, and also provide a parallel array of SWNTs establishing multiple transport pathways. However, these methods do not concurrently provide the control over the density and the chirality of SWNTs on the channel of TFT. The high-density and purely semiconducting SWNTs are essential to make the electrical properties of SWNT-based TFTs statistically uniform. Another issue related to SWNT-based electronic devices is the high contact resistance.[11–13] Ohmic contacts
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