Drain Current Characteristics of Carbon-nanotube FET (CNTFET) with SiO2, ZrO2 and HfO2 as Dielectric Materials using FETToy Code

Abstract

Over the last few decades, transistor scaling has taken the centre
stage of semiconductor devices. The scaling of metal oxide
semiconductor field effect transistor (MOSFET) with ????????????2
thickness
has been the driving force towards the technological advancement,
but continuous scaling causes a problem of short channel effects,
high leakage current, excessive process variation and reliability
issues. It is thus, of great necessity to replace the channel material
with high mobility materials such as carbon nanotubes FETs to
guarantee continued scaling of the device. Carbon Nanotube
Field Effect Transistors (CNTFET) are promising Nano-scaled
devices for implementing high performance and low power circuits.
The Nano device simulator FETtoy was used to assess the electrical
characteristics of CNTFETs as channel materials with ????????????2
, Zr????2
,
and Hf????2 as dielectric materials. Also, effects on temperature
variation were investigated. The output parameters that were studied
are: drain current, on current (????????????), off current (????????????????), threshold
swing (S), drain induced barrier lowering (DIBL), transconductance
(????????), output conductance (????????), voltage gain (????????) and carrier
injection velocity (???????????????? ). From the results obtained, carbon nanotube
as channel material with Hf????2 as dielectric material has higher
drain current of 19.3????????, at higher gate voltage of 0.6 volt and
operated near quantum capacitance limit. The obtained results were
further compared with other established academic paper published
of experimental finding under the same category and are in
agreement. This apparently indicate that carbon nanotube as
channel material with Hf????2 can be used to increase the performance
of carbon nanotube field effect transistor at room temperature with
0.88 gate control parameter to suppress the harmful subthreshold
conditions when compared with other MOSFET devices.