Bottom-up approach for carbon nanotube interconnects

Li, Jun; Ye, Qi; Cassell, Alan M.; Ng, Hou T.; Stevens, R.; Han, Jie; Meyyappan, M.

doi:10.1063/1.1566791

Cited by 493 publications

(276 citation statements)

References 17 publications

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“…1,2 The suppression of carrier backscattering brought about by the nanotube's band structure results in long mean free paths leading to ballistic transport and opens up the possibility of GHz and sub-THz applications. 3 Tailoring the intrinsic electronic properties of the CNT by choosing semiconducting or metallic CNTs has already led to the fabrication of field effect transistors 3 and sensors 4 for the former type of nanotube and interconnects 5 and field emission materials 6 for the latter.…”

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confidence: 99%

Electrical performance of carbon nanotube-polymer composites at frequencies up to 220 GHz

Alshehri

Jakubowska

Słoma

et al. 2011

Applied Physics Letters

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We have measured the sub-THz electrical response of screen printed carbon nanotube -poly(methyl methacrylate) polymer composites up to 220 GHz. The measured electrical losses using mm long coplanar waveguide geometries averaged as low as 0.15 dB/mm in the frequency range 40 GHz to 110GHz and showed a reduction in signal loss with increasing frequency; a behaviour opposite to that found in conventional metallic conductors. Between 140 and 220 GHz the electrical losses averaged 0.28 dB/mm. We show that the low electrical losses are associated with the capacitive coupling between the nanotubes and discuss potential high frequency applications. *Corresponding authors: A.Alshehri@surrey.ac.uk (Ali Alshehri) and David.Carey@surrey.ac.uk (J David Carey) 2 Carbon nanotube (CNT) electronics has firmly established itself as one of the most important areas of modern nanoelectronics. 1, 2 The suppression of carrier backscattering brought about by the nanotube's band structure results in long mean free paths leading to ballistic transport and opens up the possibility of GHz and sub-THz applications. 3 Tailoring the intrinsic electronic properties of the CNT by choosing semiconducting or metallic CNTs has already led to the fabrication of field effect transistors 3 and sensors 4 for the former type of nanotube and interconnects 5 and field emission materials 6 for the latter.Previous high frequency studies of CNTs have tended to concentrate on employing small (micron) electrode gaps, often making use of single or few singlewalled nanotube bundles as the active elements in a transistor architecture. 3 Chemical vapor deposited (CVD) carbon nanotubes bundles 7 , vertically aligned arrays 8 or nanotube ropes 9 for possible applications as electrical interconnects have also been variously explored. However such measurements using short CNTs bundles are often affected by the presence of parasitic capacitances associated with the electrodes and the presence of large impedance mismatches.Electrode architectures for transistors and interconnect applications imposes strict requirements for the environment that the nanotube can be found. Using a CNT composite frees up many of these constraints and at high frequency opens up the possibility of using large area, high bandwidth CNT electronics for communications, microwave and surface acoustic wave devices. In this Letter we have successfully characterised up to 25 mm long CNT -poly(methyl methacrylate) polymer composites up to 220 GHz. We show that the frequency response of the composites is significantly different from that of conventional metallic conductors and that capacitive coupling between the nanotubes plays an important role in the ac conduction.The samples characterised consisted of CVD grown multiwalled CNTs (average length 1.5 m, average diameter 9.5 nm, Nanocyl batch number NC3100) mixed with poly(methyl-methacrylate) (PMMA) to produce composites with 10 wt.% CNT loading. Apart from its ready availability and compatibility with high frequency electronics, PMMA was chose...

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confidence: 99%

Electrical performance of carbon nanotube-polymer composites at frequencies up to 220 GHz

Alshehri

Jakubowska

Słoma

et al. 2011

Applied Physics Letters

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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%

“…Zhang et al 69 as well as other groups [70][71][72] have investigated the current-voltage (I-V) characteristic of individual VACNFs using accurate four-point probe measurements and showed that they exhibit linear behavior. They observed an average VACNF resistivity of 4.23 Â 10 À3 XÁcm which is consistent with a simple model of charge transport where electrons travel mainly from one graphitic plane to another along the length of the nanofiber.…”

Section: Modelingmentioning

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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“…CNT exhibit impressive potentials in many applications such as electrical interconnects, (Kreupl et al 2004;Li et al 2003) thermal interface materials, (Biercuk et al 2002;Liu et al 2004) high-performance fibers, (Koziol et al 2007;Vigolo et al 2000), environmental monitoring (Lee, Sun, and Ling 2009;Lee et al 2010), and health & biotechnology (Ghule et al 2007) so on. Although the theoretical intrinsic electrical, thermal, and mechanical properties of an individual CNT are extraordinary, synthesized CNTs in reality are far from being defectfree.…”

Section: Carbon Nanotube and Microwave Interactionmentioning

confidence: 99%