Tunable threshold voltage in solution-processed single-walled carbon nanotube thin-film transistors

Seong, Narkhyeon; Kim, Tae-Hoon; Kim, Hyeonggyu; Ha, Tae‐Jun; Hong, Yongtaek

doi:10.1016/j.cap.2015.03.009

Cited by 10 publications

(9 citation statements)

References 34 publications

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“…There are three primary sources of resistance in SWNT devices (Figure a): charge injection from the contacts into the semiconductor ( R C ), , the resistance of the s-SWNT ( R SWNT ), and the resistance of the junctions between SWNT in the channel ( R J ). ,, All three of these resistance values are affected by the band gap of the SWNTs. As the band gap of the SWNT decreases, the valence band moves to higher energies, favoring injection of holes from the source and drain electrodes and reducing R C .…”

Section: Resultsmentioning

confidence: 99%

Investigating Limiting Factors in Stretchable All-Carbon Transistors for Reliable Stretchable Electronics

Chortos

Zhu

et al. 2017

ACS Nano

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Stretchable form factors enable electronic devices to conform to irregular 3D structures, including soft and moving entities. Intrinsically stretchable devices have potential advantages of high surface coverage of active devices, improved durability, and reduced processing costs. This work describes intrinsically stretchable transistors composed of single-walled carbon nanotube (SWNT) electrodes and semiconductors and a dielectric that consists of a nonpolar elastomer. The use of a nonpolar elastomer dielectric enabled hysteresis-free device characteristics. Compared to devices on SiO dielectrics, stretchable devices with nonpolar dielectrics showed lower mobility in ambient conditions because of the absence of doping from water. The effect of a SWNT band gap on device characteristics was investigated by using different SWNT sources as the semiconductor. Large-band-gap SWNTs exhibited trap-limited behavior caused by the low capacitance of the dielectric. In contrast, high-current devices based on SWNTs with smaller band gaps were more limited by contact resistance. Of the tested SWNT sources, SWNTs with a maximum diameter of 1.5 nm performed the best, with a mobility of 15.4 cm/Vs and an on/off ratio >10 for stretchable transistors. Large-band-gap devices showed increased sensitivity to strain because of a pronounced dependence on the dielectric thickness, whereas contact-limited devices showed substantially less strain dependence.

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Section: Resultsmentioning

confidence: 99%

Investigating Limiting Factors in Stretchable All-Carbon Transistors for Reliable Stretchable Electronics

Chortos

Zhu

et al. 2017

ACS Nano

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“…As a result, the high and thick SB disturbs the carrier transport at the interface between the SDC and Ag-MAC, leading to lower I on and mobility. We also extracted the channel sheet resistance (R s ) and contact resistance between the S/D and channel (R c ) of the SPM-TFT and Ag-MAC-TFT with the Y-method 58,59 to verify the SB height difference (Figure S5). Unlike R c , which is similar for SPM-TFT and Ag-MAC-TFT, the R s of the SPM-TFT is approximately seven times smaller than that of the Ag-MAC-TFT, which can be attributed to the SB height difference between S-CNT/M-CNT and S-CNT/Ag.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Selective Purity Modulation of Semiconducting Single-Walled Carbon Nanotube Networks for High-Performance Thin-Film Transistors

Kim

Yoo

et al. 2023

ACS Appl. Electron. Mater.

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Single-walled carbon nanotube (SWCNT) random networks have become strong candidates for next-generation electronics due to their exceptional mechanical, electrical, and optical properties. However, metallic nanotubes in networks generally incur a trade-off between the charge carrier mobility and on/off ratio, limiting the performance of SWCNT-based devices. Therefore, various methods to increase the purity of semiconducting nanotubes in entire random networks have been reported, but this direction has faced other issues, such as nanotube shortening, higher cost, and higher energy. Here, we introduce SWCNT random network-based thin-film transistors (SWCNT TFTs) with a varying purity profile of semiconducting SWCNTs across the channel, exploiting the superior mobility of metallic SWCNTs by partially tuning the semiconducting SWCNT purity and developing a novel perspective on metallic nanotubes in semiconductor channels. Based on the high-precision drop-on-demand capability of inkjet printing and various concentrations of semiconducting SWCNT ink, we form selectively patterned channel regions with different semiconducting SWCNT purities. The metallic nanotube-dominant region drastically increases the carrier density with a minimized Schottky barrier, while high-purity semiconducting regions at the channel boundaries effectively block off-state leakage through carrier depletion. As a result, the SWCNT TFTs with selectively patterned metallic nanotube regions show superior carrier mobility (75.50 cm 2 V −1 s −1 ) and channel width normalized on-current (34.33 nA μm −1 ) without compromising the on/off ratio (1.62 × 10 7 ). To show the feasibility of our device in high-performance electronics, we demonstrate all-inkjet-printed flexible display driving circuits with two transistors that enable low-power, high-performance operation in display applications.

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“…To further explain the I on of the three devices, we investigated the channel resistance ( R CH ) independent of the contact resistance calculated by a Y -function method. The Y -function method defined with I DS and g m is useful for extracting the mobility, V TH , R CH , and contact resistance between S/D and the active layer. , The Y value and the slope of Y can be acquired, as shown in eqs and . The R CH can be calculated by the mobility extracted from the Y method as shown in eq to exclude the contact resistance. Figure c shows R CH as a function of ρ HDC . As ρ CNT increased, R CH decreased, inducing high I on .…”

Section: Resultsmentioning

confidence: 99%

“…The Y-function method defined with I DS and g m is useful for extracting the mobility, V TH , R CH , and contact resistance between S/D and the active layer. 29,30 The Y value and the slope of Y can be acquired, as shown in eqs 1 and 2.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Inkjet-Printing-Based Density Profile Engineering of Single-Walled Carbon Nanotube Networks for Conformable High-On/Off-Performance Thin-Film Transistors

Kim

Yoo

et al. 2021

ACS Appl. Mater. Interfaces

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Random networks of single-walled carbon nanotubes (SWCNTs) offer new-form-factor electronics such as transparent, flexible, and intrinsically stretchable devices. However, the long-standing trade-off between carrier mobility and on/off ratio due to the coexistence of metallic and semiconducting nanotubes has limited the performance of SWCNT-random-network-based thin-film transistors (SWCNT TFTs), hindering their practical circuit-level applications. Methods for high-purity separation between metallic and semiconducting nanotubes have been proposed, but they require high cost and energy and are vulnerable to contamination and nanotube shortening, leading to performance degradation. Alternatively, additional structures have been proposed to reduce the off-state current, but they still compromise carrier mobility and suffer from inevitable expansion in device dimensions. Here, we propose a density-modulated SWCNT network using an inkjet-printing method as a facile approach that can achieve superior carrier mobility and a high on/off ratio simultaneously. By exploiting picoliter-scale drops on demand, we form a low-density channel network near the source and drain junctions and a high-density network at the middle of the channel. The modulated density profile forms a large band gap near the source and drain junctions that efficiently blocks electron injection under the reverse bias and a narrow band gap at the high-density area that facilitates the hole transport under the on-state bias. As a result, the density-modulated SWCNT TFTs show both high carrier mobility (27.02 cm2 V–1 s–1) and a high on/off ratio (>106). We also demonstrate all-inkjet-printed flexible inverter circuits whose gain is doubled by the density-modulated SWCNT TFTs, highlighting the feasibility of our approach for realizing high-performance flexible and conformable electronics.

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Tunable threshold voltage in solution-processed single-walled carbon nanotube thin-film transistors

Cited by 10 publications

References 34 publications

Investigating Limiting Factors in Stretchable All-Carbon Transistors for Reliable Stretchable Electronics

Investigating Limiting Factors in Stretchable All-Carbon Transistors for Reliable Stretchable Electronics

Selective Purity Modulation of Semiconducting Single-Walled Carbon Nanotube Networks for High-Performance Thin-Film Transistors

Inkjet-Printing-Based Density Profile Engineering of Single-Walled Carbon Nanotube Networks for Conformable High-On/Off-Performance Thin-Film Transistors

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