The impact of acoustic and optical-phonon scateringon on the performance of CNT-FETs is investigated using a full-quantum transport model within the NEGF formalism. Different gate lengths, dielectric materials and chiralities are considered. It is shown that the use of a high-k dielectric lowers the off-current dominated by phonon-assisted band-to-band tunneling. The device scalability is demonstrated: with the oxide thickness fixed to 1.5 nm, good performance is obtained with 15 nm and 10 nm gate lengths with SiO_2 and HfO_2 gate dielectrics, respectively. The role of phonon scattering in CNT-FETs of different chiralities is investigated for the HfO_2 devices. A similar analysis has also been carried out for source/drain underlp geometries. The results confirm that the calculation of the off-currents and delay times is strongly influenced by phonon scattering.

Phonon-scattering effects in CNT-FETs with different dimensions and dielectric materials

GRASSI, ROBERTO;POLI, STEFANO;REGGIANI, SUSANNA;GNANI, ELENA;GNUDI, ANTONIO;BACCARANI, GIORGIO
2008

Abstract

The impact of acoustic and optical-phonon scateringon on the performance of CNT-FETs is investigated using a full-quantum transport model within the NEGF formalism. Different gate lengths, dielectric materials and chiralities are considered. It is shown that the use of a high-k dielectric lowers the off-current dominated by phonon-assisted band-to-band tunneling. The device scalability is demonstrated: with the oxide thickness fixed to 1.5 nm, good performance is obtained with 15 nm and 10 nm gate lengths with SiO_2 and HfO_2 gate dielectrics, respectively. The role of phonon scattering in CNT-FETs of different chiralities is investigated for the HfO_2 devices. A similar analysis has also been carried out for source/drain underlp geometries. The results confirm that the calculation of the off-currents and delay times is strongly influenced by phonon scattering.
R. Grassi; S. Poli; S. Reggiani; E. Gnani; A. Gnudi; G. Baccarani
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/62350
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