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Investigation of carbon nanotube based field-effect transistors using atomistic quantum transport and numerical device simulation

 
: Fuchs, F.; Zienert, A.; Schuster, J.

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XXIXth International Winterschool on Electronic Properties of Novel Materials, IWEPNM 2015 : Molecular Nanostructures, Program and Abstracts, Kirchberg/Tirol, Austria, 07 - 14 March 2015
Kirchberg, 2015
pp.58-59
International Winterschool on Electronic Properties of Novel Materials (IWEPNM) <29, 2015, Kirchberg/Tirol>
English
Abstract, Electronic Publication
Fraunhofer ENAS ()

Abstract
Carbon nanotube based field-effect transistors (CNTFETs) are studied by use of two different approaches: numerical device simulation (NDS) based on the effective mass Schrödinger equation and atomistic quantum transport simulation based on the nonequilibrium Green’s functions formalism (NEGF). The studied CNTFETs consist of n-doped source- and drain-electrodes together with an ideal wrap-around gate. Using density functional theory, we extracted a parameter set for the NDS model. A band-to-band tunnel current is predicted by the NDS once the valence band edge is shifted to the Fermi energy, which increases the off-current and leads to slight ambipolar behavior. Using the NEGF instead, localized states inside the channel can be observed and the band-to-band tunnel current is suppressed, resulting in a high on/off ratio of about 107. We illustrate the potential of the studied CNTFET for future applications by varying the channel length and find excellent properties for a channel length down to 8 nm. Furthermore, the influence of the gate electrode is investigated, where good transistor behavior is observed even for a small gate of only 0.4 nm length.

: http://publica.fraunhofer.de/documents/N-337258.html