Control of Carrier Density by a Solution Method in Carbon‐Nanotube Devices

Takenobu, Taishi; Kanbara, Takeshi; Akima, Nima; Takahashi, Tetsuo; Shiraishi, Masashi; Tsukagoshi, Kazuhito; Kataura, Hiromichi; Aoyagi, Yoshinobu; Iwasa, Yoshihiro

doi:10.1002/adma.200500759

Cited by 98 publications

(100 citation statements)

References 26 publications

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“…If tetrafluorotetracyano-p-quinodimethane (F 4 TCNQ, Figure 9 b) is used as a dopant, the threshold voltage is shifted toward a positive gate voltage because of an increase in the doping concentration. [78] Although extensive studies on chemical doping have been performed, the general principle of the underlying mechanism for the choice of the dopant type has not been clarified. Recently, it has been reported that the redox potential difference between CNT and adsorbate is the key parameter in determining the charge-transfer direction.…”

Section: Chemical Dopingmentioning

confidence: 99%

Strategy for Carrier Control in Carbon Nanotube Transistors

Lee

2011

ChemSusChem

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Carbon nanotubes exhibit remarkable mechanical and electronic properties and are, therefore, being regarded as a new functional material for next generation electronics. Nevertheless, several obstacles still exist for an application in industry. The control of carriers in carbon nanotubes is of critical importance prior to an industrial application in transistors. As carbon nanotubes exhibit p-type behavior under ambient conditions, it is difficult to convert them from a p- to an n-type transistor. Also, doping control is a critical issue for applying traditional CMOS technology. Here, we discuss various approaches for preparing operating carbon nanotube transistors: i) impurity doping that employs conventional and interstitial insertion of group III or V materials, ii) chemical doping that induces charge transfer between chemicals and CNTs, iii) carrier control that utilizes the work function difference between metal and CNTs, iv) electrostatic doping that controls the carrier type by using a gate bias, and v) ambipolarity that does not use chemical doping. Advantages and drawbacks of these approaches will be discussed extensively in the text.

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Section: Chemical Dopingmentioning

confidence: 99%

Strategy for Carrier Control in Carbon Nanotube Transistors

Lee

2011

ChemSusChem

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“…An effective p-type dopant is the strong electron acceptor tetrafluoro-tetracyanoquinodimethane (F4-TCNQ). It has a very high electron affinity (i.e., E ea = 5.24 eV) and has been used successfully as a state of the art p-type dopant in organic light emitting diodes 20,[26][27][28] , carbon nanotubes [29][30][31] and on other materials 32,33 . Recently, the existence of a p-doping effect of F4-TCNQ on graphene has been suggested theoretically 34 and experimentally 25 .…”

Section: Introductionmentioning

confidence: 99%

Charge neutrality and band-gap tuning of epitaxial graphene on SiC by molecular doping

et al. 2010

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Epitaxial graphene on SiC(0001) suffers from strong intrinsic n-type doping. We demonstrate that the excess negative charge can be fully compensated by non-covalently functionalizing graphene with the strong electron acceptor tetrafluorotetracyanoquinodimethane (F4-TCNQ). Charge neutrality can be reached in monolayer graphene as shown in electron dispersion spectra from angular resolved photoemission spectroscopy (ARPES). In bilayer graphene the band gap that originates from the SiC/graphene interface dipole increases with increasing F4-TCNQ deposition and, as a consequence of the molecular doping, the Fermi level is shifted into the band gap. The reduction of the charge carrier density upon molecular deposition is quantified using electronic Fermi surfaces and Raman spectroscopy. The structural and electronic characteristics of the graphene/F4-TCNQ charge transfer complex are investigated by X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The doping effect on graphene is preserved in air and is temperature resistant up to 200• C. Furthermore, graphene non-covalent functionalization with F4-TCNQ can be implemented not only via evaporation in ultra-high vacuum but also by wet chemistry.

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“…The threshold voltage was shifted toward the positive direction with increasing doping concentration, indicated by an arrow ( figure 3(a)). This is evidence of p-doping in the SWCNT channel, where the Fermi level is downshifted toward the valence band [19]. The Breit-Wigner-Fano (BWF) line at the lower energy side of the G-band in Raman spectroscopy was slightly reduced, once again indicating the charge depletion in the SWCNTs [18,20].…”

Section: Control Of Selective N-or P-type Dopingmentioning

confidence: 88%

“…The intensity of metallic peak near 195 cm −1 in Raman spectroscopy was also significantly reduced, whereas the intensity of the semiconducting peak near 256 cm −1 did not change appreciably. This indicates a selective disintegration of metallic channels [19,28]. The remaining semiconducting channels dominated the conductance of the device.…”

Section: Control Of Doping Concentration and Disintegration Of Metallmentioning

confidence: 93%