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Issue 5, 2012
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Origin of unipolarity in carbon nanotube field effect transistors

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Abstract

Several mechanisms have been proposed for the origin of unipolar p-type behavior in carbon nanotube (CNT) transistors including (i) O2 molecules trapped in the metal/CNT contact, (ii) OH radicals on the SiO2 surface, and (iii) O2/H2O coupling on the CNT surface. Nevertheless, the underlying mechanism is far from being clearly understood. Using density functional calculations, we propose that the SiO2 substrate induces wetting of moisture, which enhances the formation of CNT–OH complexes via several intermediate chemical reactions. As a consequence, the CNT–OH complex provides deep (occupied and unoccupied) acceptor levels near the valence band, acting as an electron trap center, which is the main cause of the asymmetric unipolar behavior of CNT transistors. Based on the theory, IV characteristics are proposed in terms of gate bias and work function difference between metal and CNTs.

Graphical abstract: Origin of unipolarity in carbon nanotube field effect transistors

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Publication details

The article was received on 12 Oct 2011, accepted on 16 Nov 2011 and first published on 07 Dec 2011


Article type: Paper
DOI: 10.1039/C1JM15154A
Citation: J. Mater. Chem., 2012,22, 1994-1997

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    Origin of unipolarity in carbon nanotube field effect transistors

    D. L. Duong, S. M. Lee and Y. H. Lee, J. Mater. Chem., 2012, 22, 1994
    DOI: 10.1039/C1JM15154A

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