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Issue 19, 2016
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Towards an optimal contact metal for CNTFETs

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Downscaling of the contact length Lc of a side-contacted carbon nanotube field-effect transistor (CNTFET) is challenging because of the rapidly increasing contact resistance as Lc falls below 20–50 nm. If in agreement with existing experimental results, theoretical work might answer the question, which metals yield the lowest CNT–metal contact resistance and what physical mechanisms govern the geometry dependence of the contact resistance. However, at the scale of 10 nm, parameter-free models of electron transport become computationally prohibitively expensive. In our work we used a dedicated combination of the Green function formalism and density functional theory to perform an overall ab initio simulation of extended CNT–metal contacts of an arbitrary length (including infinite), a previously not achievable level of simulations. We provide a systematic and comprehensive discussion of metal–CNT contact properties as a function of the metal type and the contact length. We have found and been able to explain very uncommon relations between chemical, physical and electrical properties observed in CNT–metal contacts. The calculated electrical characteristics are in reasonable quantitative agreement and exhibit similar trends as the latest experimental data in terms of: (i) contact resistance for Lc = ∞, (ii) scaling of contact resistance Rc(Lc); (iii) metal-defined polarity of a CNTFET. Our results can guide technology development and contact material selection for downscaling the length of side-contacts below 10 nm.

Graphical abstract: Towards an optimal contact metal for CNTFETs

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The article was received on 03 Feb 2016, accepted on 30 Mar 2016 and first published on 01 Apr 2016

Article type: Paper
DOI: 10.1039/C6NR01012A
Citation: Nanoscale, 2016,8, 10240-10251
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    Towards an optimal contact metal for CNTFETs

    A. Fediai, D. A. Ryndyk, G. Seifert, S. Mothes, M. Claus, M. Schröter and G. Cuniberti, Nanoscale, 2016, 8, 10240
    DOI: 10.1039/C6NR01012A

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