4 research outputs found
Simulation of phonon-assisted band-to-band tunneling in carbon nanotube field-effect transistors
Electronic transport in a carbon nanotube (CNT) metal-oxide-semiconductor
field effect transistor (MOSFET) is simulated using the non-equilibrium Green's
functions method with the account of electron-phonon scattering. For MOSFETs,
ambipolar conduction is explained via phonon-assisted band-to-band
(Landau-Zener) tunneling. In comparison to the ballistic case, we show that the
phonon scattering shifts the onset of ambipolar conduction to more positive
gate voltage (thereby increasing the off current). It is found that the
subthreshold swing in ambipolar conduction can be made as steep as 40mV/decade
despite the effect of phonon scattering.Comment: 13 pages, 4 figure
Modeling a Schottky-barrier carbon nanotube field-effect transistor with ferromagnetic contacts
In this study, a model of a Schottky-barrier carbon nanotube field- effect
transistor (CNT-FET), with ferromagnetic contacts, has been developed. The
emphasis is put on analysis of current-voltage characteristics as well as shot
(and thermal) noise. The method is based on the tight-binding model and the
non- equilibrium Green's function technique. The calculations show that, at
room temperature, the shot noise of the CNT FET is Poissonian in the
sub-threshold region, whereas in elevated gate and drain/source voltage regions
the Fano factor gets strongly reduced. Moreover, transport properties strongly
depend on relative magnetization orientations in the source and drain contacts.
In particular, one observes quite a large tunnel magnetoresistance, whose
absolute value may exceed 50%.Comment: 8 pages, 4 figure