Contact resistance between metal and carbon nanotube interconnects: Effect of work function and wettability

Lim, Seong Chu; Jang, Jin Ho; Bae, Deg‐Hyo; Han, Gang; Lee, Sunwoo; Yeo, In‐Seok; Lee, Young Hee

doi:10.1063/1.3255016

Cited by 184 publications

(114 citation statements)

References 28 publications

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“…The 3D electrostatics accounts of the full device geometry: the SWNTs on the quartz substrate are terminated by source (S) and drain (D) contacts, and covered by insulating material Tc-resist. The results show that carrier transport depends sensitively on (i) the diameter of the tubes within the as-growth array, (ii) the work-function of the contact materials (Pd (5.1 eV), Au (5.0 eV), Mo (4.6 eV), Ti (4.33 eV), Al (4.1 eV), and Mg (3.7 eV)) 40,54,59 and (iii) effective applied bias, V DS (extracted by correlating the equivalent trench depths in Tc-resist for DC and microwave inputs). The source to drain of this two-terminal device is separated by L 0 ¼ 15 mm.…”

Section: Discussionmentioning

confidence: 99%

Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes

et al. 2014

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Recent progress in the field of single-walled carbon nanotubes (SWNTs) significantly enhances the potential for practical use of this remarkable class of material in advanced electronic and sensor devices. One of the most daunting challenges is in creating large-area, perfectly aligned arrays of purely semiconducting SWNTs (s-SWNTs). Here we introduce a simple, scalable, large-area scheme that achieves this goal through microwave irradiation of aligned SWNTs grown on quartz substrates. Microstrip dipole antennas of low work-function metals concentrate the microwaves and selectively couple them into only the metallic SWNTs (m-SWNTs). The result allows for complete removal of all m-SWNTs, as revealed through systematic experimental and computational studies of the process. As one demonstration of the effectiveness, implementing this method on large arrays consisting of B20,000 SWNTs completely removes all of the m-SWNTs (B7,000) to yield a purity of s-SWNTs that corresponds, quantitatively, to at least to 99.9925% and likely significantly higher.

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Section: Discussionmentioning

confidence: 99%

Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes

et al. 2014

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“…It has been reported that interaction energies of transition metals enhance with the number of vacancies in d orbital. If the vacancy is the same, the closer to the nucleus the d orbital is, the higher the interaction energy is, [14]. We can confer that the 3d metal of Ti possesses higher interaction energy than the 5d metal of Hf, even though they have the same number of vacancies in d orbital.…”

Section: Theory and Considerationmentioning

confidence: 71%

The Influence of the Asymmetric Metal Electrodes on the Self-assembly of Single-walled Carbon Nanotubes by AC Dielectrophoresis

Zhang

Chen

2018

IOP Conf. Ser.: Mater. Sci. Eng.

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There are two procedures in the single-walled carbon nanotubes (SWCNTs) DEP (dielectrophoresis) assembly process, including the DEP and suspension removal. This paper mainly pays attention to the effects of the suspension removal procedure on the assembly efficiency. We found that the interaction energy between the SWCNTs and electrode metal materials plays a major role in preventing the arriving SWCNTs from getting off the electrodes when the suspension is blown-off, which will impact the DEP assembly yield of SWCNTs further. Three kinds of metal materials having various interaction energy with SWCNTs with the order of Ti>Hf>Al were chosen as the electrode materials and then the SWCNTs DEP assembly experiments were carried out. Our results show that the assembly yields exhibit the accordant order with that of the interaction energy of Ti>Hf>Al, which demonstrates our deduction. IntroductionAfter the past two decades of intensive research on their intrinsic features and diverse application potential, carbon nanotubes (CNTs) have evolved into studious application exploitations, especially for the CNT-based electronic devices, including transistors, chemical and biological sensors, diodes, and so forth. Because of the wide application in photovoltaic and betavoltaic microcells, infrared detectors and microwave rectifiers, SWCNT-based diodes have attracted immense research attention. They mainly have three structures, such as doped p-n junction, split-gates, and Schottky barrier (SB). Among them, the SB diode with an asymmetric configuration of "high-work-function (h) metal/SWCNT/low-work-function (l) metal" has the advantages of very simple fabrication and is doping-free resulting in avoiding the failure induced by dopant diffusion or freeze whether in high or extremely low temperatures. For the widespread application of SWCNT-based devices, one of the crucial obstacles of the state of the art is how to make the large-scale assembly of SWCNTs precise, efficient and compatible with conventional micro-fabrication technologies as well. Although the chemical vapor deposition (CVD) can achieve direct growth of SWCNTs on substrates [1], the high growth temperature makes it incompatible with the current complementary metal-oxide-semiconductor (CMOS) technologies [1]. Post-synthesis assembly techniques are the promising alternative to the CVD technique owning to their very simple set-up and operation at room temperature [2][3][4]. DEP is advantageous over other post-processed techniques because it allows controlling the position and density of the assembled SWCNTs between pre-fabricated electrodes and

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“…111 The possible application of VANTAs and VACNFs as microelectronic interconnects has driven many studies to characterize their end-contact quality. 71,[111][112][113][114][115] The reported end-contact resistances vary significantly from one measurement to another suggesting a wide spectrum of influencing parameters. Important parameters are the surface roughness of the metal underlayer as well as its surface oxidation, 115 the wettability of the metal underlayer and its work function, 112 and the growth conditions.…”

Section: Quality Factormentioning

confidence: 99%

“…71,[111][112][113][114][115] The reported end-contact resistances vary significantly from one measurement to another suggesting a wide spectrum of influencing parameters. Important parameters are the surface roughness of the metal underlayer as well as its surface oxidation, 115 the wettability of the metal underlayer and its work function, 112 and the growth conditions. 111 In general, the magnitude of the reported contact resistances for an individual interface is in the order of a few to tens of kilo ohms.…”

Section: Quality Factormentioning

confidence: 99%

Vertically aligned carbon based varactors

Ghavanini

Enoksson

Bengtsson

et al. 2011

Journal of Applied Physics

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This paper gives an assessment of vertically aligned carbon based varactors and validates their potential for future applications. The varactors discussed here are nanoelectromechanical devices which are based on either vertically aligned carbon nanofibers or vertically aligned carbon nanotube arrays. A generic analytical model for parallel plate nanoelectromechanical varactors based on previous works is developed and is used to formulate a universal expression for their voltage-capacitance relation. Specific expressions for the nanofiber based and the nanotube based varactors are then derived separately from the generic model. This paper also provides a detailed review on the fabrication of carbon based varactors and pays special attention to the challenges in realizing such devices. Finally, the performance of the carbon based varactor is assessed in accordance with four criteria: the static capacitance, the tuning ratio, the quality factor, and the operating voltage. Although the reported performance is still far inferior to other varactor technologies, our prognosis which stems from the analytical model shows a promise of a high quality factor as well as a potential for high power handling for carbon based varactors.

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Contact resistance between metal and carbon nanotube interconnects: Effect of work function and wettability

Cited by 184 publications

References 28 publications

Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes

Microwave purification of large-area horizontally aligned arrays of single-walled carbon nanotubes

The Influence of the Asymmetric Metal Electrodes on the Self-assembly of Single-walled Carbon Nanotubes by AC Dielectrophoresis

Vertically aligned carbon based varactors

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