Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

Xie, Xu; Wahab, Muhammad Abdul; Li, Yuhang; Islam, Ahmad E.; Tomic, Bojan; Huang, Junfeng; Burns, Branden; Seabron, Eric; Dunham, Simon; Du, Frank; Lin, Jonathan B.; Wilson, William L.; Song, Jizhou; Alam, Muhammad Ashraful; Rogers, John A.

doi:10.1063/1.4916537

Cited by 13 publications

(12 citation statements)

References 36 publications

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“…John Rogers et al developed a promising approach to achieve 99.9925% purity CNT arrays by using nanoscale thermocapillary flow method . The Joule heating around the m‐SWCNTs induces thermal gradients that drive flow of thermocapillary resist away from the m‐SWNTs to form open trenches.…”

Section: Progresses In Aligned Cnt Thin‐film Electronicsmentioning

confidence: 99%

Advances in High‐Performance Carbon‐Nanotube Thin‐Film Electronics

Zhu

et al. 2019

Adv Elect Materials

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urgency, and provided a 'beyond CMOS' strategy. In 2008, ITRS suggested industry community to find new emerging materials and devices to replace the state-of-theart silicon and sustain Moore's law. [12][13][14][15] Among emerging channel materials for exploring aggressively scaled MOS FETs, single-walled carbon nanotube (SWCNT) is a strong competitor due to its extremely high carrier mobility, ultrathin body, and excellent stability. [16][17][18][19][20] Its quasi 1D body can provide much better electrostatic gate control on the channel than Si and other semiconductors counterparts (e.g., III-V compounds or Ge). [21][22][23] Since the first demonstration of the carbon nanotube field effect transistor (CNT FET) in 1998, significant progresses have been made on CNT FETs based electronics in the past 20 years, especially for next generation digital elements for ICs. On one hand, intensive researches have been focusing on FETs based on individual CNTs to study the transport properties, optimize device performance, and explore the performance limit. A classic work is the dopingfree fabrication of CMOS CNT FETs, which maintains the high intrinsic carrier mobility and long mean-free-length (MFL) of CNT since the dopant scattering is excluded. Therefore, highperformance ballistic CMOS FETs are easily achievable via a simpler process than conventional Si CMOS technology. [24][25][26][27] Based on doping free approach, CNT CMOS FETs with a gate length of 10 nm have been successfully demonstrated to perform better than Si CMOS FETs with the same gate length but at a lower supply voltage. [28] Furthermore, ultrasmall CNT FETs with a gate length of 5 nm or footprint of 40 nm have been realized through optimizing device structure and process, which has approached the quantum limit of conventional FETs by using approximately only one electron per switching operation on one CNT. [29,30] On the other hand, various scale of ICs have been fabricated on CNT thin films to demonstrate the industrialization possibility, for example, fundamental logic gates with excellent electrical characteristic, [31] high-speed ring oscillators that can work in gigahertz regime, [32,33] and complex and largescale ICs, including decoder, [34] full-adder, [35,36] or even a CNTbased center processing unit (CPU) using p-type CNT FETs or P-MOS. [37] These successful demonstrations of medium or large-scale CNT circuits illustrate the uniformity and stability of CNT materials and transistors, as well as the development potential on ultralarge scale ICs applications. However, access to ideal materials, device structure, and fabrication remain a challenge if we are targeting at the industrialization of highperformance CNT ICs. To minimize confusion, we use the word "CNT thin film FET" to distinguish high performance The device standards necessary for high-performance carbon nanotube (CNT) field-effect transistors (FETs) for integrated circuits (ICs) are discussed by illustrating key device metrics. Recent advances in solution-processed CNT network-materials a...

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Section: Progresses In Aligned Cnt Thin‐film Electronicsmentioning

confidence: 99%

Advances in High‐Performance Carbon‐Nanotube Thin‐Film Electronics

Zhu

et al. 2019

Adv Elect Materials

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“…[ 90,91 ] The selective CVD growth remains a great challenge. [102][103][104][105][106] As compared with the previously used electrical breakdown method, the thermocapillary method can lead to complete elimination of metallic CNTs in the conducting channel, while maintain the semiconducting CNTs undamaged. [92][93][94][95][96][97][98] However, even such a high purity cannot satisfy the requirement of highperformance electronic and optoelectronic device and circuits.…”

Section: High-purity Cnt Filmsmentioning

confidence: 99%

“…Nevertheless significant progress has been made recently on the direct CVD growth of single chirality and ultrahigh density CNT arrays . On the post‐growth removal of metallic CNTs, the thermocapillary method shows great promise to obtain high quality parallel arrays of pure semiconducting CNTs . As compared with the previously used electrical breakdown method, the thermocapillary method can lead to complete elimination of metallic CNTs in the conducting channel, while maintain the semiconducting CNTs undamaged .…”

Section: Cnt‐film‐based High‐performance Photovoltaic Devicesmentioning

confidence: 99%

Toward High‐Performance Carbon Nanotube Photovoltaic Devices

Wang

Peng

2016

Advanced Energy Materials

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PV) devices, direct-bandgap, broad spectral response, large absorption coeffi cient and fast response speed on the order of picosecond, etc. [ 4,6,12,13 ] Tremendous efforts have been made to convert the excellent intrinsic properties of CNTs into high-performance devices. Optoelectronic research has been focused mainly on nanoscale light-emitting diode (LED), photodetector, solar cell and novel physical discoveries such as two-photon absorption, multi-excitons generation, photovoltage multiplication and so on. [14][15][16][17][18][19][20] Here, the fundamental properties of CNT energy band structure and corresponding optical characteristics are reviewed. Then photovoltaic research developments of various kinds of CNT diodes, with particular emphasis on barrier-free-bipolar-diode (BFBD) devices fabricated via a dopingfree method are discussed. For pushing CNT PV devices toward applications, the status of CNT thin-fi lm-based PV devices, including recent breakthroughs made on solution-processed semiconducting CNT separation techniques, and the utilization of these materials for constructing high-performance PV diodes are discussed. The doping-free technique has been combined with virtual contacts to multiply photovoltage and thus to signifi cantly improve the performance and signal to noise ratio of PV devices. It is demonstrated that CNT PV device has a superior broadband response from visible to near infrared, high room temperature detectivity that can be compared with state-of-the-art InGaAs detectors, and extremely good temperature and temporal stability. This article will end with a discussion on the challenges that still lay ahead, and possible solutions. Basic Optical Properties of Carbon NanotubesAs shown in Figure 1 a, a CNT is composed of hexagonal honeycomb sp 2 lattice, and various chirality CNTs can be formed with different orientations relative to the tube axis, giving rise to distinct properties of either semiconducting or metallic. [ 21 ] Semiconducting CNTs have been recommended as the potential channel material for replacing silicon to extend Moore's law. [ 5 ] However, beyond Moore, it is also of great signifi cance to build high-performance optoelectronic devices and circuits. [ 12,22 ] The excellent properties of CNT stem from its basic band structure, which is signifi cant to discuss its unique physical Photovoltaic (PV) infrared (IR)-based devices are important for a variety of industrial and scientifi c applications, such as IR imaging, biological sensing, day-night surveillance and in solar cells. However, most high-end IR PV devices made of conventional semiconductors need to be cooled to achieve high performance, while these materials usually are also not stable under strong illumination. Carbon nanotubes (CNTs) are direct-bandgap materials with a broad spectral response and a large absorption coeffi cient, which is most desired for building high-performance PV devices. Main progresses on CNT PVs in the past 15 years is reviewed, emphasizing recent breakthrough of CNT IR photodetectors b...

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“…In a typical synthetic mixture, approximately two-thirds of the chiralities are semiconductors and the remainder is made up of metals. Chirality-selective chemistry has long been sought after as the key to sorting by chirality, on-chip passivation, and nanotube lithography . For semiconducting SWCNT-based optoelectronic and biomedical devices, even a small amount of heterogeneity can dramatically hinder their performance. , Chirality selective chemistry may provide a chemical route to selectively block conductive channels in nanotube arrays directly on-chip .…”

Section: Introductionmentioning

confidence: 99%

“…Chirality-selective chemistry has long been sought after as the key to sorting by chirality, on-chip passivation, and nanotube lithography . For semiconducting SWCNT-based optoelectronic and biomedical devices, even a small amount of heterogeneity can dramatically hinder their performance. , Chirality selective chemistry may provide a chemical route to selectively block conductive channels in nanotube arrays directly on-chip . The selective chemistry would also add a new layer of chemical control that is orthogonal to existing methods for improving resolution between difficult-to-separate SWCNT chiralities. − …”

Section: Introductionmentioning

confidence: 99%

Chirality-Selective Functionalization of Semiconducting Carbon Nanotubes with a Reactivity-Switchable Molecule

2017

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Chirality-selective functionalization of semiconducting single-walled carbon nanotubes (SWCNTs) has been a difficult synthetic goal for more than a decade. Here we describe an on-demand covalent chemistry to address this intriguing challenge. Our approach involves the synthesis and isolation of a chemically inert diazoether isomer that can be switched to its reactive form in situ by modulation of the thermodynamic barrier to isomerization with pH and visible light that resonates with the optical frequency of the nanotube. We found that it is possible to completely inhibit the reaction in the absence of light, as determined by the limit of sensitive defect photoluminescence (less than 0.01% of the carbon atoms are bonded to a functional group). This optically driven diazoether chemistry makes it possible to selectively functionalize a specific SWCNT chirality within a mixture. Even for two chiralities that are nearly identical in diameter and electronic structure, (6,5)- and (7,3)-SWCNTs, we are able to activate the diazoether compound to functionalize the less reactive (7,3)-SWCNTs, driving the chemical reaction to near exclusion of the (6,5)-SWCNTs. This work opens opportunities to chemically tailor SWCNTs at the single chirality level for nanotube sorting, on-chip passivation, and nanoscale lithography.

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Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

Cited by 13 publications

References 36 publications

Advances in High‐Performance Carbon‐Nanotube Thin‐Film Electronics

Advances in High‐Performance Carbon‐Nanotube Thin‐Film Electronics

Toward High‐Performance Carbon Nanotube Photovoltaic Devices

Chirality-Selective Functionalization of Semiconducting Carbon Nanotubes with a Reactivity-Switchable Molecule

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